Publications by authors named "Simon Claridge"

64 Publications

Pacemaker-induced ventricular fibrillation during radiofrequency catheter ablation for ventricular tachycardia.

J Arrhythm 2021 Apr 14;37(2):368-369. Epub 2021 Feb 14.

Department of Cardiology Royal Bournemouth and Christchurch Hospitals Bournemouth UK.

Prior to ventricular tachycardia ablation, this patient's cardiac implantable electronic device (CIED) was temporarily programmed to backup pacing mode with tachycardia therapies disabled. During radiofrequency energy delivery, the patient developed ventricular fibrillation requiring emergent cardioversion. Electrogram interrogation showed that the CIED switched to noise reversion mode during ablation. The consequent asynchronous pacing resulted in a paced QRS landing on an intrinsic T wave, inducing ventricular fibrillation. This serves as an important reminder that asynchronous pacing consequent to CIED oversensing could occur in any procedure that could cause electromagnetic interference such as radiofrequency cathteter ablation.
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http://dx.doi.org/10.1002/joa3.12517DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8021979PMC
April 2021

Evaluation of [N]ammonia positron emission tomography as a potential method for quantifying glutamine synthetase activity in the human brain.

EJNMMI Res 2020 Dec 3;10(1):146. Epub 2020 Dec 3.

School of Biomedical Engineering and Imaging Sciences, St Thomas' Hospital, King's College London, London, SE1 7EH, UK.

Purpose: The conversion of synaptic glutamate to glutamine in astrocytes by glutamine synthetase (GS) is critical to maintaining healthy brain activity and may be disrupted in several brain disorders. As the GS catalysed conversion of glutamate to glutamine requires ammonia, we evaluated whether [N]ammonia positron emission tomography (PET) could reliability quantify GS activity in humans.

Methods: In this test-retest study, eight healthy volunteers each received two dynamic [N]ammonia PET scans on the morning and afternoon of the same day. Each [N]ammonia scan was preceded by a [O]water PET scan to account for effects of cerebral blood flow (CBF).

Results: Concentrations of radioactive metabolites in arterial blood were available for both sessions in five of the eight subjects. Our results demonstrated that kinetic modelling was unable to reliably distinguish estimates of the kinetic rate constant k (related to GS activity) from K (related to [N]ammonia brain uptake), and indicated a non-negligible back-flux of [N] to blood (k). Model selection favoured a reversible one-tissue compartmental model, and [N]ammonia K correlated reliably (r = 0.72-0.92) with [O]water CBF.

Conclusion: The [N]ammonia PET method was unable to reliably estimate GS activity in the human brain but may provide an alternative index of CBF.
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http://dx.doi.org/10.1186/s13550-020-00731-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7714883PMC
December 2020

High mean entropy calculated from cardiac MRI texture analysis is associated with antitachycardia pacing failure.

Pacing Clin Electrophysiol 2020 07 21;43(7):737-745. Epub 2020 Jun 21.

Cardiology Department, Guy's and St Thomas' NHS Foundation Trust, London, UK.

Background: Antitachycardia pacing (ATP), which may avoid unnecessary implantable cardioverter-defibrillator (ICD) shocks, does not always terminate ventricular arrhythmias (VAs). Mean entropy calculated using cardiac magnetic resonance texture analysis (CMR-TA) has been shown to predict appropriate ICD therapy. We examined whether scar heterogeneity, quantified by mean entropy, is associated with ATP failure and explore potential mechanisms using computer modeling.

Methods: A subanalysis of 114 patients undergoing CMR-TA where the primary endpoint was delivery of appropriate ICD therapy (ATP or shock therapy) was performed. Patients receiving appropriate ICD therapy (n = 33) were dichotomized into "successful ATP" versus "shock therapy" groups. In silico computer modeling was used to explore underlying mechanisms.

Results: A total of 16 of 33 (48.5%) patients had successful ATP to terminate VA, and 17 of 33 (51.5%) patients required shock therapy. Mean entropy was significantly higher in the shock versus successful ATP group (6.1 ± 0.5 vs 5.5 ± 0.7, P = .037). Analysis of patients receiving ATP (n = 22) showed significantly higher mean entropy in the six of 22 patients that failed ATP (followed by rescue ICD shock) compared to 16 of 22 that had successful ATP (6.3 ± 0.7 vs 5.5 ± 0.7, P = .048). Computer modeling suggested inability of the paced wavefront in ATP to successfully propagate from the electrode site through patchy fibrosis as a possible mechanism of failed ATP.

Conclusions: Our findings suggest lower scar heterogeneity (mean entropy) is associated with successful ATP, whereas higher scar heterogeneity is associated with more aggressive VAs unresponsive to ATP requiring shock therapy that may be due to inability of the paced wavefront to propagate through scar and terminate the VA circuit.
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http://dx.doi.org/10.1111/pace.13969DOI Listing
July 2020

Ultra-High-Density Activation Mapping to Aid Isthmus Identification of Atrial Tachycardias in Congenital Heart Disease.

JACC Clin Electrophysiol 2019 12 30;5(12):1459-1472. Epub 2019 Oct 30.

LIRYC/Hopital du Haut Leveque, Bordeaux, France.

Objectives: A new electroanatomic mapping system (Rhythmia, Boston Scientific, Marlborough, Massachusetts) using a 64-electrode mapping basket is now available; we systematically assessed its use in complex congenital heart disease (CHD).

Background: The incidence of atrial arrhythmias post-surgery for CHD is high. Catheter ablation has emerged as an effective treatment, but is hampered by limitations in the mapping system's ability to accurately define the tachycardia circuit.

Methods: Mapping and ablation data of 61 patients with CHD (35 males, age 45 ± 14 years) from 8 tertiary centers were reviewed.

Results: Causes were as follows: Transposition of Great Arteries (atrial switch) (n = 7); univentricular physiology (Fontans) (n = 8); Tetralogy of Fallot (n = 10); atrial septal defect (ASD) repair (n = 15); tricuspid valve (TV) anomalies (n = 10); and other (n = 11). The total number of atrial arrhythmias was 86. Circuits were predominantly around the tricuspid valve (n = 37), atriotomy scar (n = 10), or ASD patch (n = 4). Although the majority of peri-tricuspid circuits were cavo-tricuspid-isthmus dependent (n = 30), they could follow a complex route between the annulus and septal resection, ASD patch, coronary sinus, or atriotomy. Immediate ablation success was achieved in all but 2 cases; with follow-up of 12 ± 8 months, 7 patients had recurrence.

Conclusions: We demonstrate the feasibility of the basket catheter for mapping complex CHD arrhythmias, including with transbaffle and transhepatic access. Although the circuits often involve predictable anatomic landmarks, the precise critical isthmus is often difficult to predict empirically. Ultra-high-density mapping enables elucidation of circuits in this complex anatomy and allows successful treatment at the isthmus with a minimal lesion set.
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http://dx.doi.org/10.1016/j.jacep.2019.08.001DOI Listing
December 2019

Evidence of reverse electrical remodelling by non-invasive electrocardiographic imaging to assess acute and chronic changes in bulk ventricular activation following cardiac resynchronisation therapy.

J Electrocardiol 2020 Jan - Feb;58:96-102. Epub 2019 Nov 26.

Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, United Kingdom; Cardiovascular Department, Guys and St Thomas NHS Foundation Trust, London, United Kingdom.

Introduction: Cardiac resynchronisation therapy (CRT) corrects electrical dyssynchrony. However, the temporal changes in the electrical timing according to substrate are unclear. We used electrocardiographic imaging (ECGi) for serial non-invasive assessment of the underlying electrical substrate and its response to resynchronisation.

Material And Methods: ECGi activation maps were constructed 1 day and 6 months post CRT implant. ECGi maps were analysed offline to determine the total ventricular activation time (TVaT) and the time for the bulk of ventricular activation (10 to 90 percentile activation; VaT Index). Statistical analysis was performed using repeated measures ANOVA with post-hoc pairwise comparisons using paired t-tests. The % relative change within each time point was also calculated and compared between the two time points.

Results: Eleven CRT patients were studied. Both total and bulk ventricular activation significantly decreased with CRT turned ON at day 1. Intrinsic (CRT OFF) TVaT and VaT Index at day 1 were 143 ± 23 and 84 ± 20 ms, respectively, and they significantly decreased post CRT to 115 ± 26 ms (P < 0.001) and 49 ± 17 ms (P < 0.05), respectively. The relative change at day 1 was also statistically significant for TVaT (19 ± 12%, P < 0.001) and VaT Index (39 ± 25%, P < 0.001). After 6 months, the relative decrease in TVaT with CRT ON remained stable (19% vs. 18% at day 1 and 6 months, respectively) whereas reduction the in VaT Index was decreased 39% vs. 26% at day 1 and 6 months, respectively. In non-ischaemic patients both total and bulk activation times reduced following CRT. Volumetric responders exhibited an electrical remodelling for bulk activation not apparent in Non-responders, after 6 months of CRT ON.

Conclusions: Intrinsic bulk myocardium activation becomes more rapid and synchronous with CRT. The bulk activation time is more susceptible to improvement by CRT in ischaemic patients and volumetric responders. These observations are consistent with CRT causing reverse electrophysiological remodelling in the bulk myocardium, but not in late-activating ischaemic or fibrotic regions.
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http://dx.doi.org/10.1016/j.jelectrocard.2019.11.051DOI Listing
November 2019

Transvenous lead extraction procedures in women based on ESC-EHRA EORP European Lead Extraction ConTRolled ELECTRa registry: is female sex a predictor of complications?

Europace 2019 12;21(12):1890-1899

Direttore UO Cardiologia 2 SSN, Azienda Ospedaliero-Universitaria, Pisa, Italy.

Aims: Female sex is considered an independent risk factor of transvenous leads extraction (TLE) procedure. The aim of the study was to evaluate the effectiveness of TLE in women compared with men.

Methods And Results: A post hoc analysis of risk factors and effectiveness of TLE in women and men included in the ESC-EHRA EORP ELECTRa registry was conducted. The rate of major complications was 1.96% in women vs. 0.71% in men; P = 0.0025. The number of leads was higher in men (mean 1.89 vs. 1.71; P < 0.0001) with higher number of abandoned leads in women (46.04% vs. 34.82%; P < 0.0001). Risk factors of TLE differed between the sexes, of which the major were: signs and symptoms of venous occlusion [odds ratio (OR) 3.730, confidence interval (CI) 1.401-9.934; P = 0.0084], cumulative leads dwell time (OR 1.044, CI 1.024-1.065; P < 0.001), number of generator replacements (OR 1.029, CI 1.005-1.054; P = 0.0184) in females and the number of leads (OR 6.053, CI 2.422-15.129; P = 0.0001), use of powered sheaths (OR 2.742, CI 1.404-5.355; P = 0.0031), and white blood cell count (OR 1.138, CI 1.069-1.212; P < 0.001) in males. Individual radiological and clinical success of TLE was 96.29% and 98.14% in women compared with 98.03% and 99.21% in men (P = 0.0046 and 0.0098).

Conclusion: The efficacy of TLE was lower in females than males, with a higher rate of periprocedural major complications. The reasons for this difference are probably related to disparities in risk factors in women, including more pronounced leads adherence to the walls of the veins and myocardium. Lead management may be key to the effectiveness of TLE in females.
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http://dx.doi.org/10.1093/europace/euz277DOI Listing
December 2019

Emerging role of cardiac computed tomography in heart failure.

ESC Heart Fail 2019 10 10;6(5):909-920. Epub 2019 Aug 10.

Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London, UK.

Despite medical advancements, the prognosis of patients with heart failure remains poor. While echocardiography and cardiac magnetic resonance imaging remain at the forefront of diagnosing and monitoring patients with heart failure, cardiac computed tomography (CT) has largely been considered to have a limited role. With the advancements in scanner design, technology, and computer processing power, cardiac CT is now emerging as a valuable adjunct to clinicians managing patients with heart failure. In the current manuscript, we review the current applications of cardiac CT to patients with heart failure and also the emerging areas of research where its clinical utility is likely to extend into the realm of treatment, procedural planning, and advanced heart failure therapy implementation.
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http://dx.doi.org/10.1002/ehf2.12479DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6816076PMC
October 2019

Optimization of CRT programming using non-invasive electrocardiographic imaging to assess the acute electrical effects of multipoint pacing.

J Arrhythm 2019 Apr 14;35(2):267-275. Epub 2019 Jan 14.

Division of Imaging Sciences and Biomedical Engineering King's College London London UK.

Aim: Quadripolar lead technology and multi-point pacing (MPP) are important clinical adjuncts in cardiac resynchronization therapy (CRT) pacing aimed at reducing the rate of non-response to therapy. Mixed results have been achieved using MPP and it is critical to identify which patients require this approach and how to configure their MPP stimulation, in order to achieve optimal electrical resynchronization.

Methods & Results: We sought to investigate whether electrocardiographic imaging (ECGi), using the CARDIOINSIGHT inverse ECG mapping system, could identify alterations in electrical resynchronization during different methods of device optimization. In no patient did a single form of programming optimization provide the best electrical response. The effects of utilizing MPP were idiosyncratic and highly patient specific. ECGi activation maps were clearly able to discern changes in bulk LV activation during differing MPP programming. In two of the five subjects, MPP resulted in more rapid activation of the left ventricle compared to standard CRT; however, in the remaining three patients, the use of MPP did not appear to acutely improve electrical resynchronization. Crucially, this cohort showed evidence of extensive LV scarring which was well visualized using both CMR and ECGi voltage mapping.

Conclusions: Our work suggests a potential role for ECGi in the optimization of non-responders to CRT, as it allows the fusion of activation maps and scar analysis above and beyond interrogation of the 12 lead ECG.
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http://dx.doi.org/10.1002/joa3.12153DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6457383PMC
April 2019

Comparison of Echocardiographic and Electrocardiographic Mapping for Cardiac Resynchronisation Therapy Optimisation.

Cardiol Res Pract 2019 21;2019:4351693. Epub 2019 Feb 21.

Division of Imaging Sciences and Biomedical Engineering, King's College London, London, UK.

Study Hypothesis: We sought to investigate the association between echocardiographic optimisation and ventricular activation time in cardiac resynchronisation therapy (CRT) patients, obtained through the use of electrocardiographic mapping (ECM). We hypothesised that echocardiographic optimisation of the pacing delay between the atrial and ventricular leads-atrioventricular delay (AVD)-and the delay between ventricular leads-interventricular pacing interval (VVD)-would correlate with reductions in ventricular activation time.

Background: Optimisation of AVD and VVD may improve CRT patient outcome. Optimal delays are currently set based on echocardiographic indices; however, acute studies have found that reductions in bulk ventricular activation time correlate with improvements in acute haemodynamic performance.

Materials And Methods: Twenty-one patients with established CRT criteria were recruited. After implantation, patients underwent echo-guided optimisation of the AVD and VVD. During this procedure, the participants also underwent noninvasive ECM. ECM maps were constructed for each AVD and VVD. ECM maps were analysed offline. Total ventricular activation time (TVaT) and a ventricular activation time index (VaT) were calculated to identify the optimal AVD and VVD timings that gave the minimal TVaT and VaT values. We correlated cardiac output with these electrical timings.

Results: Echocardiographic programming optimisation was not associated with the greatest reductions in biventricular activation time (VaT and TVaT). Instead, bulk activation times were reduced by a further 20% when optimised with ECM. A significant inverse correlation was identified between reductions in bulk ventricular activation time and improvements in LVOT VTI ( < 0.001), suggesting that improved ventricular haemodynamics are a sequelae of more rapid ventricular activation.

Conclusions: EAM-guided programming optimisation may achieve superior fusion of activation wave fronts leading to improvements in CRT response.
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http://dx.doi.org/10.1155/2019/4351693DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6409049PMC
February 2019

Mean entropy predicts implantable cardioverter-defibrillator therapy using cardiac magnetic resonance texture analysis of scar heterogeneity.

Heart Rhythm 2019 08 5;16(8):1242-1250. Epub 2019 Mar 5.

Cardiology Department, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom; School of Biomedical Engineering and Imaging Sciences, King's College London, United Kingdom.

Background: Risk stratification of ventricular arrhythmia remains complex in patients with ischemic and nonischemic cardiomyopathy.

Objective: The purpose of this study was to determine whether scar heterogeneity, quantified by mean entropy, predicts appropriate implantable cardioverter-defibrillator (ICD) therapy. We hypothesized that higher mean entropy calculated from cardiac magnetic resonance texture analysis (CMR-TA) will predict appropriate ICD therapy.

Methods: Consecutive patients underwent CMR imaging before ICD implantation. Short-axis left ventricular scar was manually segmented. CMR-TA was performed using a Laplacian filter to extract and augment image features to create a scar texture from which histogram analysis of pixel intensity was used to calculate mean entropy. The primary end point was appropriate ICD therapy.

Results: A total of 114 patients underwent CMR-TA (ischemic cardiomyopathy [ICM]: n = 70; nonischemic cardiomyopathy [NICM]: n = 44) with a median follow-up of 955 days (interquartile range 691-1185 days). Mean entropy was significantly higher in the ICM group (5.7 ± 0.7 vs 5.5 ± 0.7; P= .045). Overall, 33 patients received appropriate ICD therapy. Using optimized cutoff values from receiver operating characteristic curves, Kaplan-Meier survival analysis demonstrated time until first appropriate therapy was significantly shorter in the high mean entropy group (P = .003). Multivariable analysis showed that mean entropy was the sole predictor of appropriate ICD therapy (hazard ratio 1.882; 95% confidence interval 1.083-3.271; P = .025). In the ICM group, mean entropy remained an independent predictor of appropriate ICD therapy, whereas in the NICM group, precontrast T1 values were the sole predictor.

Conclusion: Scar heterogeneity, quantified by mean entropy using CMR-TA, was an independent predictor of appropriate ICD therapy in the mixed cardiomyopathy cohort and ICM-only group, suggesting a potential role for CMR-TA in predicting ventricular arrhythmia and risk-stratifying patients for ICD implantation.
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http://dx.doi.org/10.1016/j.hrthm.2019.03.001DOI Listing
August 2019

Procedural outcomes associated with transvenous lead extraction in patients with abandoned leads: an ESC-EHRA ELECTRa (European Lead Extraction ConTRolled) Registry Sub-Analysis.

Europace 2019 Apr;21(4):645-654

Clinique Pasteur, Management of Cardiac Arrhythmias, 45 Avenue de Lombez, Toulouse, France.

Aims: The decision to abandon or extract superfluous leads remains controversial. We sought to compare procedural outcome of patients with and without abandoned leads undergoing transvenous lead extraction (TLE).

Methods And Results: An analysis of the ESC-EHRA European Lead Extraction ConTRolled ELECTRa registry was conducted. Patients were stratified into two groups based on the presence (Group 1) or absence (Group 2) of abandoned leads at the time for extraction. Out of 3508 TLE procedures, 422 patients (12.0%) had abandoned leads (Group 1). Group 1 patients were older and more likely to have implantable cardioverter-defibrillator devices, infection indication (78.8% vs. 49.8%), and vegetations (24.6% vs. 15.3%). Oldest lead dwelling time was longer in Group 1 (10.9 vs. 6.3 years) as was the number of extracted leads per patient (3.2 vs. 1.7). Manual traction failure (94.5% vs. 78.8%), powered sheath use (50.7% vs. 28.4%), and femoral approach were higher in Group 1 (P < 0.0001). Procedural success rate and clinical success (89.8% vs. 96.6%, P < 0.0001) were lower in Group 1. Major complication including deaths (5.5% vs. 2.3%, P = 0.0007) and procedure related major complications (3.3% vs. 1.4%, P = 0.0123) were higher in Group 1. The presence of abandoned leads at the time of TLE was an independent predictor of clinical failure [odds ratio (OR) 2.31, confidence interval (CI) 1.57-3.40] and complications [OR 1.69, CI 1.22-2.35]. receiver-operating characteristic curve analysis showed a dwell time threshold of 9 years for radiological failure and major complications.

Conclusions: Previously abandoned leads at the time of TLE were associated with increased procedural complexity, clinical failure, and major complication, which may have important implications for future studies regarding managing of lead failures.
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http://dx.doi.org/10.1093/europace/euy307DOI Listing
April 2019

Transvenous lead extraction in patients with cardiac resynchronization therapy devices is not associated with increased 30-day mortality.

Europace 2019 Jun;21(6):928-936

Department of Cardiology, Lower Ground Floor, South Wing, Guy's and St Thomas' NHS Foundation Trust, Westminster Bridge Road, London, UK.

Aims: Transvenous lead extraction (TLE) may be necessary due to system infection/erosion or lead malfunction. Cardiac resynchronization therapy (CRT) patients undergoing TLE may be at greater risk due to increased comorbidities. We examined whether patients with CRT systems undergoing TLE had more comorbidities and higher 30-day mortality than those with non-CRT devices.

Methods And Results: All TLEs between October 2000 and December 2016 were prospectively collected. During this period 925 TLEs occurred (CRT group 231, non-CRT group 694). Cardiac resynchronization therapy patients were older (68.1 ± 10.8 years vs. 64.3 ± 16.1 years, P = 0.024); more likely male (85.7% vs. 69%, P < 0.001); had lower mean left ventricular ejection fraction (34.1 ± 12.7% vs. 48.3 ± 12.9%, P < 0.001); had higher prevalence of renal impairment (33.8% vs. 13.7%, P < 0.001) and were more likely to have ≥2 comorbidities (84% vs. 40.1%, P < 0.001). Mean lead dwell time was lower in the CRT group (5.6 ± 5.5 years vs. 7.6 ± 7.1 years, P = 0.002). There was no significant difference in all-cause 30-day mortality rates between CRT (3.0%, n = 7) and non-CRT patients (2.0%, n = 14) (P = 0.443). The majority of deaths in both groups were due to sepsis. Univariate and multivariate analysis showed age, renal impairment and sepsis were associated with increased risk of 30-day mortality. Transvenous lead extraction of a CRT system did not predict 30-day mortality.

Conclusion: Transvenous lead extraction in CRT patients was not associated with increased 30-day mortality when compared with non-CRT patients. Age, renal impairment and sepsis were independent predictors of 30-day mortality. Sepsis was the main cause of 30-day mortality.
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http://dx.doi.org/10.1093/europace/euy290DOI Listing
June 2019

Left ventricular activation-recovery interval variability predicts spontaneous ventricular tachyarrhythmia in patients with heart failure.

Heart Rhythm 2019 05 5;16(5):702-709. Epub 2018 Dec 5.

Guy's and St Thomas' Hospital, London, United Kingdom.

Background: Enhanced beat-to-beat variability of repolarization is strongly linked to arrhythmogenesis and is largely due to variation in ventricular action potential duration (APD). Previous studies in humans have relied on QT interval measurements; however, a direct relationship between beat-to-beat variability of APD and arrhythmogenesis in humans has yet to be demonstrated.

Objective: This study aimed to explore the beat-to-beat repolarization dynamics in patients with heart failure at the level of ventricular APD.

Methods: Forty-three patients with heart failure and implanted cardiac resynchronization therapy - defibrillator devices were studied. Activation-recovery intervals as a surrogate for APD were recorded from the left ventricular epicardial lead while pacing from the right ventricular lead to maintain a constant cycle length.

Results: During a mean follow-up of 23.6±13.6 months, 11 patients sustained ventricular fibrillation/ventricular tachycardia (VT/VF) and received appropriate implantable cardioverter-defibrillator therapies (antitachycardia pacing or shock therapy). Activation-recovery interval variability (ARIV) was significantly greater in patients with subsequent VT/VF than in those without VT/VF (3.55±1.3 ms vs 2.77±1.09 ms; P=.047). Receiver operating characteristic curve analysis (area under the curve 0.71; P=.046) suggested high- and low-risk ARIV groups for VT/VF. Kaplan-Meier survival analysis demonstrated that the time until first appropriate therapy for VT/VF was significantly shorter in the high-risk ARIV group (P=.028). ARIV was a predictor for VT/VF in the multivariate Cox model (hazard ratio 1.623; 95% confidence interval 1.1-2.393; P=.015).

Conclusion: Increased left ventricular ARIV is associated with an increased risk of VT/VF in patients with heart failure.
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http://dx.doi.org/10.1016/j.hrthm.2018.11.013DOI Listing
May 2019

Is heart failure with mid range ejection fraction (HFmrEF) a distinct clinical entity or an overlap group?

Int J Cardiol Heart Vasc 2018 Dec 6;21:1-6. Epub 2018 Sep 6.

Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London, SE1 7EH, United Kingdom.

Background: The new category of heart failure (HF), Heart Failure with mid range Ejection Fraction (HFmrEF) has recently been proposed with recent publications reporting that HFmrEF represents a transitional phase. The aim of this study was to determine the prevalence and clinical characteristics of patients with HFmrEF and to establish what proportion of patients transitioned to other types of HF, and how this affected clinical outcomes.

Methods And Results: Patients were diagnosed with HF according to the 2016 ESC guidelines. Clinical outcomes and variables were recorded for all consecutive in-patients referred to the heart failure service. In total, 677 patients with new HF were identified; 25.6% with HFpEF, 21% with HFmrEF and 53.5% with HFrEF. While clinical characteristics and prognostic factors of HFmrEF were intermediate between HFrEF and HFpEF, HFmrEF patients had the best outcome, with higher mortality in the HFrEF population (p 0.02) and higher HF rehospitalisation rates in the HFpEF population ( < 0.01).38.7% of the HFmrEF patients transitioned (56.4% to HFpEF and 43.6% to HFrEF) with fewest deaths in the patients that transitioned to HFpEF (p 0.04), and fewest HF readmissions in the patients that remained as HFmrEF (<0.01).

Conclusion: HFmrEF patients had the best outcomes, compared to high rates of mortality seen in patients with HFrEF and high rates of HF readmissions seen in patients with HFpEF. Only 1/3 of HFmrEF patients transitioned during follow up, with the lowest mortality seen in patients transitioning to HFpEF.
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http://dx.doi.org/10.1016/j.ijcha.2018.06.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6128173PMC
December 2018

Variation in activation time during bipolar vs extended bipolar left ventricular pacing.

J Cardiovasc Electrophysiol 2018 12 5;29(12):1675-1681. Epub 2018 Oct 5.

Department of Imaging Sciences and Biomedical Engineering, King's College London, London, UK.

Background: Cardiac resynchronization therapy (CRT) is typically delivered via quadripolar leads that allow stimulation using either true bipolar pacing, where stimulation occurs between two electrodes (BP) on the quadripolar lead, or extended bipole (EBP) left ventricular (LV) pacing, with the quadripolar electrodes and right ventricular coil acting as the cathode and anode, respectively. True bipolar pacing is associated with reductions in mortality and it has been postulated that these differences are the result of enhanced electrical activation.

Materials And Methods: Patients undergoing a CRT underwent an electrocardiographic imaging study where electrical activation data were recorded while different LV pacing vectors were temporarily programmed.

Results: There were no differences in the total electrical activation times or dispersion of electrical activation between biventricular pacing with bipolar or corresponding EBP LV vector configurations (left ventricular total activation time [LVtat] BP 74.70 ± 18.07 vs EBP 72.4 ± 22.64; P = 0.45). When dichotomized according to etiology, no difference was observed in the activation time with either BP or EBP pacing (LVtat BP ischemic cardiomyopathy 72.2 ± 17.4 vs BP dilated cardiomyopathy 79.9 ± 18.9; P = 0.38).

Conclusions: Bipolar pacing alters the mechanical activation sequence of the LV and is associated with reductions in all-cause mortality. It has been postulated these benefits derive from improvements in electromechanical activation of the LV. Our study would suggest that true bipolar pacing does not necessarily result in more favorable activation of the LV or improved electrical resynchronization and other mechanisms should be explored.
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http://dx.doi.org/10.1111/jce.13714DOI Listing
December 2018

Guidance for Optimal Site Selection of a Leadless Left Ventricular Endocardial Electrode Improves Acute Hemodynamic Response and Chronic Remodeling.

JACC Clin Electrophysiol 2018 07 2;4(7):860-868. Epub 2018 May 2.

Division of Imaging Sciences and Biomedical Engineering, King's College London, United Kingdom; Cardiology Department, Guys and St. Thomas' National Health Service (NHS) Foundation Trust, London, United Kingdom.

Objectives: This study hypothesized that guided implants, in which the optimal left ventricular endocardial (LV) pacing location was identified and targeted, would improve acute markers of contractility and chronic markers of cardiac resynchronization (CRT) response.

Background: Biventricular endocardial (BiV) pacing may offer a potential benefit over standard CRT; however, the optimal LV pacing site is highly variable. Indiscriminately delivered BiV pacing is associated with a reverse remodeling response rate of between 40% and 60%.

Methods: Registry of centers implanting a wireless, LV pacing system (WiSE-CRT System, EBR Systems, Sunnyvale, California); John Radcliffe Hospital (Oxford, United Kingdom), Guy's and St. Thomas' Hospital (London, United Kingdom), and The James Cook University Hospital (Middlesbrough, United Kingdom). Centers used a combination of preprocedural imaging and electroanatomical mapping the identify the optimal LV site.

Results: A total of 26 patients across the 3 centers underwent a guided implant. Patients were predominantly male with a mean age of 68.8 ± 8.4 years, the mean LV ejection fraction was 34.2 ± 7.8%. The mean QRS duration was 163.8 ± 26.7 ms, and 30.8% of patients had an ischemic etiology. It proved technically feasible to selectively target and deploy the pacing electrode in a chosen endocardial segment in almost all cases, with a similar complication rate to that observed during indiscriminate BiV. Ninety percent of patients met the definition of echocardiographic responder. Reverse remodeling was observed in 71%.

Conclusions: Guided endocardial implants were associated with a higher degree of chronic LV remodeling compared with historical nonguided approaches.
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http://dx.doi.org/10.1016/j.jacep.2018.03.011DOI Listing
July 2018

Optimal site selection and image fusion guidance technology to facilitate cardiac resynchronization therapy.

Expert Rev Med Devices 2018 08 30;15(8):555-570. Epub 2018 Jul 30.

a Division of Imaging Sciences and Biomedical Engineering , King's College London , London , United Kingdom.

Introduction: Cardiac resynchronization therapy (CRT) has emerged as one of the few effective treatments for heart failure. However, up to 50% of patients derive no benefit. Suboptimal left ventricle (LV) lead position is a potential cause of poor outcomes while targeted lead deployment has been associated with enhanced response rates. Image-fusion guidance systems represent a novel approach to CRT delivery, allowing physicians to both accurately track and target a specific location during LV lead deployment.

Areas Covered: This review will provide a comprehensive evaluation of how to define the optimal pacing site. We will evaluate the evidence for delivering targeted LV stimulation at sites displaying favorable viability or advantageous mechanical or electrical properties. Finally, we will evaluate several emerging image-fusion guidance systems which aim to facilitate optimal site selection during CRT.

Expert Commentary: Targeted LV lead deployment is associated with reductions in morbidity and mortality. Assessment of tissue characterization and electrical latency are critical and can be achieved in a number of ways. Ultimately, the constraints of coronary sinus anatomy have forced the exploration of novel means of delivering CRT including endocardial pacing which hold promise for the future of CRT delivery.
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http://dx.doi.org/10.1080/17434440.2018.1502084DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6178093PMC
August 2018

Changes in contractility determine coronary haemodynamics in dyssynchronous left ventricular heart failure, not vice versa.

Int J Cardiol Heart Vasc 2018 Jun 4;19:8-13. Epub 2018 Apr 4.

NIHR Biomedical Research Centre, School of Cardiovascular Medicine and Sciences, King's College London, United Kingdom.

Background: Biventricular pacing has been shown to increase both cardiac contractility and coronary flow acutely but the causal relationship is unclear. We hypothesised that changes in coronary flow are secondary to changes in cardiac contractility. We sought to examine this relationship by modulating coronary flow and cardiac contractility.

Methods: Contractility and lusitropy were altered by varying the location of pacing in 8 patients. Coronary autoregulation was transiently disabled with intracoronary adenosine. Simultaneous coronary flow velocity, coronary pressure and left ventricular pressure data were measured in the different pacing settings with and without hyperaemia and wave intensity analysis performed.

Results: Multisite pacing was effective at altering left ventricular contractility and lusitropy (pos. dp/dt -13% to +10% and neg. dp/dt -15% to +17% compared to baseline). Intracoronary adenosine decreased microvascular resistance (362.5 mm Hg/s/m to 156.7 mm Hg/s/m, p < 0.001) and increased LAD flow velocity (22 cm/s vs 45 cm/s, p < 0.001) but did not acutely change contractility or lusitropy. The magnitude of the dominant accelerating wave, the Backward Expansion Wave, was proportional to the degree of contractility as well as lusitropy (r = 0.47, p < 0.01 and r = -0.50, p < 0.01). Perfusion efficiency (the proportion of accelerating waves) increased at hyperaemia (76% rest vs 81% hyperaemia, p = 0.04). Perfusion efficiency correlated with contractility and lusitropy at rest (r = 0.43 & -0.50 respectively, p = 0.01) and hyperaemia (r = 0.59 & -0.6, p < 0.01).

Conclusions: Acutely increasing coronary flow with adenosine in patients with systolic heart failure does not increase contractility. Changes in coronary flow with biventricular pacing are likely to be a consequence of enhanced cardiac contractility from resynchronization and not vice versa.
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http://dx.doi.org/10.1016/j.ijcha.2018.03.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6016072PMC
June 2018

Left Lateral Fluoroscopy and Xiphisternum Removal to Avoid Bowel Perforation and Enable Epicardial Ventricular Tachycardia Ablation.

JACC Clin Electrophysiol 2018 Jun;4(6):844-845

Department of Cardiology, University Hospital Southampton, Southampton, United Kingdom.

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http://dx.doi.org/10.1016/j.jacep.2018.02.018DOI Listing
June 2018

Real-Time X-MRI-Guided Left Ventricular Lead Implantation for Targeted Delivery of Cardiac Resynchronization Therapy.

JACC Clin Electrophysiol 2017 08 26;3(8):803-814. Epub 2017 Apr 26.

Department of Imaging Sciences and Biomedical Engineering, King's College London, & Guy's and St Thomas' Hospital, London, United Kingdom.

Objectives: This study sought to test the feasibility of a purpose-built, integrated software platform to process, analyze, and overlay cardiac magnetic resonance (CMR) data in real time within a combined cardiac catheter laboratory and magnetic resonance imaging scanner suite (X-MRI) to guide left ventricular (LV) lead implantation.

Background: Suboptimal LV lead position is a major determinant of poor cardiac resynchronization therapy (CRT) response, and the optimal site is highly patient specific. Pacing myocardial scar is associated with poorer outcomes; conversely, targeting latest mechanical activation (LMA) may improve them.

Methods: Fourteen patients (age 74 ± 5.1 years; New York Heart Association functional class: 2.7 ± 0.4; 86% ischemic with ejection fraction 27 ± 7.6%; QRSd: 157 ± 19 ms) underwent CMR followed by immediate CRT implantation using derived scar and dyssynchrony data, overlaid onto fluoroscopy in an X-MRI suite. Rapid LV segmentation enabled detailed scar quantification, identification of LMA segments, and selection of myocardial targets. At coronary venography, the CMR-derived 3-dimensional shell was fused, enabling identification of viable venous targets subtended by target segments for LV lead placement.

Results: The platform was successful in all 14 patients, of whom 10 (71%) were paced in pre-procedurally defined target segments. Pacing in CMR-defined target segments (out of scar) showed a significant decrease in the LV capture threshold (mean difference: 2.4 [1.5 to 3.2]; p < 0.001) and shorter paced QRS duration (mean difference: 25 [15 to 34]; p < 0.001) compared with pacing in areas of CMR determined scar. In 5 (36%) patients with extensive scar in the posterolateral wall, CMR guidance enabled successful lead delivery in an alternative anatomically favorable site. Radiation dose and implant times were similar to historical controls (p = NS).

Conclusions: Real-time CMR-guided LV lead placement is feasible and achievable in a single clinical setting and may prove helpful to preferentially select sites for LV lead placement.
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http://dx.doi.org/10.1016/j.jacep.2017.01.018DOI Listing
August 2017

The interaction of QRS duration with cardiac magnetic resonance derived scar and mechanical dyssynchrony in systolic heart failure: Implications for cardiac resynchronization therapy.

Int J Cardiol Heart Vasc 2018 Mar 13;18:81-85. Epub 2017 Dec 13.

Guy's and St. Thomas' Hospitals, London, United Kingdom.

Background: Trials using echocardiographic mechanical dyssynchrony (MD) parameters in narrow QRS patients have shown a negative response to CRT. We hypothesized MD in these patients may relate to myocardial scar rather than electrical dyssynchrony.

Methods: We determined the prevalence of cardiac magnetic resonance (CMR) derived measures of MD in 130 systolic heart failure patients with both broad (≥ 130 ms - BQRS) and narrow QRS duration (< 130 ms - NQRS). We assessed whether late gadolinium enhancement derived scar might explain the presence of MD amongst narrow QRS patients. Dyssynchrony was calculated on the basis of a systolic dyssynchrony index (SDI).

Results: Fifty-nine patients (45%) had a NQRS and the remaining had QRS ≥ 130 ms (BQRS group). 25% of NQRS patients had MD based on SDI. In all narrow and broad QRS patients with MD there was a significantly lower scar volume than those without MD (7.4 ± 10.5% vs 13.7 ± 13.3% vs. p < 0.01). This was the case in the BQRS group with a significantly lower scar burden in patients with MD (5.0 ± 7.7% vs 15.4 ± 15.6%, p < 0.01). Notably in the NQRS group this difference was absent with an equal scar burden in patients with MD 13.3 ± 13.9% and without MD 12.5 ± 11%, p = 0.92.

Conclusions: 25% of patients with systolic heart failure and a NQRS (< 130 ms) have CMR derived mechanical dyssynchrony. Our findings suggest MD in this group may be secondary to myocardial scar rather than electrical dyssynchrony and therefore not amenable to correction by CRT. This may give insight into non-response and potential harm from CRT in this group.
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http://dx.doi.org/10.1016/j.ijcha.2017.11.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5941225PMC
March 2018

Electrical latency predicts the optimal left ventricular endocardial pacing site: results from a multicentre international registry.

Europace 2018 12;20(12):1989-1996

Division of Imaging Sciences and Biomedical Engineering, King's College London, 4th Floor, North Wing, London, UK.

Aims: The optimal site for biventricular endocardial (BIVENDO) pacing remains undefined. Acute haemodynamic response (AHR) is reproducible marker of left ventricular (LV) contractility, best expressed as the change in the maximum rate of LV pressure (LV-dp/dtmax), from a baseline state. We examined the relationship between factors known to impact LV contractility, whilst delivering BIVENDO pacing at a variety of LV endocardial (LVENDO) locations.

Methods And Results: We compiled a registry of acute LVENDO pacing studies from five international centres: Johns Hopkins-USA, Bordeaux-France, Eindhoven-The Netherlands, Oxford-United Kingdom, and Guys and St Thomas' NHS Foundation Trust, London-UK. In all, 104 patients incorporating 687 endocardial and 93 epicardial pacing locations were studied. Mean age was 66 ± 11 years, mean left ventricular ejection fraction 24.6 ± 7.7% and mean QRS duration of 163 ± 30 ms. In all, 50% were ischaemic [ischaemic cardiomyopathy (ICM)]. Scarred segments were associated with worse haemodynamics (dp/dtmax; 890 mmHg/s vs. 982 mmHg/s, P < 0.01). Delivering BiVENDO pacing in areas of electrical latency was associated with greater improvements in AHR (P < 0.01). Stimulating late activating tissue (LVLED >50%) achieved greater increases in AHR than non-late activating tissue (LVLED < 50%) (8.6 ± 9.6% vs. 16.1 ± 16.2%, P = 0.002). However, the LVENDO pacing location with the latest Q-LV, was associated with the optimal AHR in just 62% of cases.

Conclusions: Identifying viable LVENDO tissue which displays late electrical activation is crucial to identifying the optimal BiVENDO pacing site. Stimulating late activating tissue (LVLED >50%) yields greater improvements in AHR however, the optimal location is frequently not the site of latest activation.
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http://dx.doi.org/10.1093/europace/euy052DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6275469PMC
December 2018

Beat-to-Beat Variability of Ventricular Action Potential Duration Oscillates at Low Frequency During Sympathetic Provocation in Humans.

Front Physiol 2018 4;9:147. Epub 2018 Apr 4.

Guy's and St Thomas' Hospital, London, United Kingdom.

The temporal pattern of ventricular repolarization is of critical importance in arrhythmogenesis. Enhanced beat-to-beat variability (BBV) of ventricular action potential duration (APD) is pro-arrhythmic and is increased during sympathetic provocation. Since sympathetic nerve activity characteristically exhibits burst patterning in the low frequency range, we hypothesized that physiologically enhanced sympathetic activity may not only increase BBV of left ventricular APD but also impose a low frequency oscillation which further increases repolarization instability in humans. Heart failure patients with cardiac resynchronization therapy defibrillator devices ( = 11) had activation recovery intervals (ARI, surrogate for APD) recorded from left ventricular epicardial electrodes alongside simultaneous non-invasive blood pressure and respiratory recordings. Fixed cycle length was achieved by right ventricular pacing. Recordings took place during resting conditions and following an autonomic stimulus (Valsalva). The variability of ARI and the normalized variability of ARI showed significant increases post Valsalva when compared to control ( = 0.019 and = 0.032, respectively). The oscillatory behavior was quantified by spectral analysis. Significant increases in low frequency (LF) power ( = 0.002) and normalized LF power ( = 0.019) of ARI were seen following Valsalva. The Valsalva did not induce changes in conduction variability nor the LF oscillatory behavior of conduction. However, increases in the LF power of ARI were accompanied by increases in the LF power of systolic blood pressure (SBP) and the rate of systolic pressure increase (dP/dt). Positive correlations were found between LF-SBP and LF-dP/dt ( = 0.933, < 0.001), LF-ARI and LF-SBP ( = 0.681, = 0.001) and between LF-ARI and LF-dP/dt ( = 0.623, = 0.004). There was a strong positive correlation between the variability of ARI and LF power of ARI ( = 0.679, < 0.001). In heart failure patients, physiological sympathetic provocation induced low frequency oscillation (~0.1 Hz) of left ventricular APD with a strong positive correlation between the LF power of APD and the BBV of APD. These findings may be of importance in mechanisms underlying stability/instability of repolarization and arrhythmogenesis in humans.
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http://dx.doi.org/10.3389/fphys.2018.00147DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5893843PMC
April 2018

A cost effectiveness study establishing the impact and accuracy of implementing the NICE guidelines lowering plasma NTproBNP threshold in patients with clinically suspected heart failure at our institution.

Int J Cardiol 2018 04;257:131-136

Department of Cardiology, Guy's and St Thomas' NHS Foundation Trust, London SE1 7EH, United Kingdom; Division of Imaging Sciences and Biomedical Engineering, King's College London, SE1 7EH, United Kingdom.

Aims: The 2014 National Institute of Clinical Excellence (NICE) guidelines on the management of acute heart failure recommended using a plasma NT-proBNP threshold of 300pg/ml to assist in ruling out the diagnosis of heart failure (HF), updating previous guidelines recommending using a threshold of 400pg/ml. NICE based their recommendations on 6 studies performed in other countries. This study sought to determine the diagnostic and economic implications of using these thresholds in a large unselected UK population.

Methods: Patient and clinical demographics were recorded for all consecutive suspected HF patients over 12months, as well as clinical outcomes including time to HF hospitalisation and time to death (follow up 15.8months).

Results: Of 1995 unselected patients admitted with clinically suspected HF, 1683 (84%) had a NTproBNP over the current NICE recommended threshold, of which 35% received a final diagnosis of HF. Lowering the threshold from 400 to 300pg/ml would have involved screening an additional 61 patients and only would have identified one new patient with HF (sensitivity 0.985, NPV 0.976, area under the curve (AUC) at 300pg/ml 0.67; sensitivity 0.983, NPV 0.977, AUC 0.65 at 400pg/ml). The economic implications of lowering the threshold would have involved additional costs of £42,842.04 (£702.33 per patient screened, or £ 42,824.04 per new HF patient).

Conclusion: Applying the recent updated NICE guidelines to an unselected real world population increases the AUC but would have a significant economic impact and only identified one new patient with heart failure.
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http://dx.doi.org/10.1016/j.ijcard.2017.10.126DOI Listing
April 2018

Relationship between vectorcardiographic QRS, myocardial scar quantification, and response to cardiac resynchronization therapy.

J Electrocardiol 2018 May - Jun;51(3):457-463. Epub 2018 Feb 8.

Department of Physiology, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, The Netherlands.

Purpose: To investigate the relationship between vectorcardiography (VCG) and myocardial scar on cardiac magnetic resonance (CMR) imaging, and whether combining these metrics may improve cardiac resynchronization therapy (CRT) response prediction.

Methods: Thirty-three CRT patients were included. QRS, T and QRST were derived from the ECG-synthesized VCG. CMR parameters reflecting focal scar core (Scar, Gray) and diffuse fibrosis (pre-T1, extracellular volume [ECV]) were assessed. CRT response was defined as ≥15% reduction in left ventricular end-systolic volume after six months' follow-up.

Results: VCG QRS, T and QRST inversely correlated with focal scar (R = -0.44--0.58 for Scar, p ≤ 0.010), but not with diffuse fibrosis. Scar, Gray and QRS predicted CRT response with AUCs of 0.692 (p = 0.063), 0.759 (p = 0.012) and 0.737 (p = 0.022) respectively. A combined ROC-derived threshold for Scar and QRS resulted in 92% CRT response rate for patients with large QRS and small Scar or Gray.

Conclusion: QRS is inversely associated with focal scar on CMR. Incremental predictive value for CRT response is achieved by a combined CMR-QRS analysis.
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http://dx.doi.org/10.1016/j.jelectrocard.2018.01.009DOI Listing
March 2019

Predictors and outcomes of patients requiring repeat transvenous lead extraction of pacemaker and defibrillator leads.

Pacing Clin Electrophysiol 2018 02 24;41(2):155-160. Epub 2018 Jan 24.

Department of Cardiology, Guy's and St Thomas' Hospital Trust, London, SE1 7EH, UK.

Background: A proportion of patients who undergo an initial lead extraction procedure will require a second, repeat extraction. Data regarding this clinical entity are scarce and neither the predisposing risk factors for, nor outcomes from, these procedures have been described previously. We sought to determine the incidence, risk factors, and outcomes of repeat lead extraction.

Methods: A database of extraction procedures from 2001 to 2015 was analyzed. Repeat extraction procedures were identified and the indication for extraction was dichotomized into infection and lead-related problems. Univariate and multivariate analyses were performed to identify predictors of repeat extraction.

Results: 807 extraction procedures were identified in 755 patients of whom 6% required a repeat extraction. At multivariate analysis, only suffering a major complication at the initial extraction procedure (odds ratio [OR] 21.5, 95% confidence interval [CI] 2.69-171.92; P < 0.01), complexity of device (cardiac resynchronization devices/implantable cardioverter defibrillators) (OR 2.58, 95% CI 1.2-5.2; P = 0.01), and age (OR 1.02 per year, 95% CI 1.0-1.4; P  =  0.03) were significant predictors of repeat extraction. When repeat extraction was required for infection there was a significant increase in mortality compared with those who did not require a second procedure (36% vs 23%; P  =  0.02).

Conclusions: Repeat lead extraction is required in 6% of cases. Complexity of device, age at extraction, and a major complication at the first extraction were predictors of repeat extraction. Mortality is significantly increased where the repeat procedure is for infection. Clinicians should alert patients to the potential need for further extraction and the increased risks of repeat procedures when indicated for infection.
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http://dx.doi.org/10.1111/pace.13266DOI Listing
February 2018

To the Editor- The cost of cardiac resynchronization therapy generator replacement?

Heart Rhythm 2018 03 8;15(3):e35-e36. Epub 2017 Dec 8.

Division of Imaging Sciences, King's College London, London, United Kingdom.

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http://dx.doi.org/10.1016/j.hrthm.2017.12.008DOI Listing
March 2018

Myocardial strain computed at multiple spatial scales from tagged magnetic resonance imaging: Estimating cardiac biomarkers for CRT patients.

Med Image Anal 2018 Jan 31;43:169-185. Epub 2017 Oct 31.

Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom.

Abnormal cardiac motion can indicate different forms of disease, which can manifest at different spatial scales in the myocardium. Many studies have sought to characterise particular motion abnormalities associated with specific diseases, and to utilise motion information to improve diagnoses. However, the importance of spatial scale in the analysis of cardiac deformation has not been extensively investigated. We build on recent work on the analysis of myocardial strains at different spatial scales using a cardiac motion atlas to find the optimal scales for estimating different cardiac biomarkers. We apply a multi-scale strain analysis to a 43 patient cohort of cardiac resynchronisation therapy (CRT) patients using tagged magnetic resonance imaging data for (1) predicting response to CRT, (2) identifying septal flash, (3) estimating QRS duration, and (4) identifying the presence of ischaemia. A repeated, stratified cross-validation is used to demonstrate the importance of spatial scale in our analysis, revealing different optimal spatial scales for the estimation of different biomarkers.
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http://dx.doi.org/10.1016/j.media.2017.10.004DOI Listing
January 2018

Cost-effectiveness of a risk-stratified approach to cardiac resynchronisation therapy defibrillators (high versus low) at the time of generator change.

Heart 2018 03 29;104(5):416-422. Epub 2017 Sep 29.

Department of Imaging Sciences, King's College London, London, UK.

Objective: Responders to cardiac resynchronisation therapy whose device has a defibrillator component and who do not receive a therapy in the lifetime of the first generator have a very low incidence of appropriate therapy after box change. We investigated the cost implications of using a risk stratification tool at the time of generator change resulting in these patients being reimplanted with a resynchronisation pacemaker.

Methods: A decision tree was created using previously published data which had demonstrated an annualised appropriate defibrillator therapy risk of 2.33%. Costs were calculated at National Health Service (NHS) national tariff rates (2016-2017). EQ-5D utility values were applied to device reimplantations, admissions and mortality data, which were then used to estimate quality-adjusted life-years (QALYs) over 5 years.

Results: At 5 years, the incremental cost of replacing a resynchronisation defibrillator device with a second resynchronisation defibrillator versus resynchronisation pacemaker was £5045 per patient. Incremental QALY gained was 0.0165 (defibrillator vs pacemaker), resulting in an incremental cost-effectiveness ratio (ICER) of £305 712 per QALYs gained. Probabilistic sensitivity analysis resulted in an ICER of £313 612 (defibrillator vs pacemaker). For reimplantation of all patients with a defibrillator rather than a pacemaker to yield an ICER of less than £30 000 per QALY gained (current NHS cut-off for approval of treatment), the annual arrhythmic event rate would need to be 9.3%. The budget impact of selective replacement was a saving of £2 133 985 per year.

Conclusions: Implanting low-risk patients with a resynchronisation defibrillator with the same device at the time of generator change is not cost-effective by current NHS criteria. Further research is required to understand the impact of these findings on individual patients at the time of generator change.
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http://dx.doi.org/10.1136/heartjnl-2017-311749DOI Listing
March 2018