Publications by authors named "Sylvain Ploux"

98 Publications

Left-axis deviation in patients with nonischemic heart failure and left bundle branch block is a purely electrical phenomenon.

Heart Rhythm 2021 Apr 6. Epub 2021 Apr 6.

Cardio-Thoracic Unit, Bordeaux University Hospital (CHU), Pessac-Bordeaux, France; IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac-Bordeaux, France.

Background: Possible mechanisms of left-axis deviation (LAD) in the setting of left bundle branch block (LBBB) include differences in cardiac electrophysiology, structure, or anatomic axis.

Objective: The purpose of this study was to clarify the mechanism(s) responsible for LAD in patients with LBBB.

Methods: Twenty-nine patients with nonischemic cardiomyopathies and LBBB underwent noninvasive electrocardiographic imaging (ECGi), cardiac computed tomography, and magnetic resonance imaging in order to define ventricular electrical activation, characterize cardiac structure, and determine the cardiac anatomic axis.

Results: Sixteen patients had a normal QRS axis (NA) (mean axis 8° ± 23°), whereas 13 patients had LAD (mean axis -48° ± 13°; P <.001). Total activation times were longer in the LAD group (112 ± 25 ms vs 91 ± 14 ms; P = .01) due to delayed activation of the basal anterolateral region (107 ± 10 ms vs 81 ± 17 ms; P <.001). Left ventricular (LV) activation in patients with LAD was from apex to base, in contrast to a circumferential pattern of activation in patients with NA. Apex-to-base delay was longer in the LA group (95 ± 13 ms vs 64 ± 21 ms; P <.001) and correlated with QRS frontal axis (R = 0.67; P <.001). Both groups were comparable with regard to LV end-diastolic volume (295 ± 84 mL vs LAD 310 ± 91 mL; P = .69), LV mass (177 ± 33 g vs LAD 180 ± 37 g; P = .83), and anatomic axis.

Conclusion: LAD in LBBB seems to be due to electrophysiological abnormalities rather than structural factors or cardiac anatomic axis.
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http://dx.doi.org/10.1016/j.hrthm.2021.03.042DOI Listing
April 2021

Accuracy of a Smartwatch-Derived ECG for Diagnosing Bradyarrhythmias, Tachyarrhythmias, and Cardiac Ischemia.

Circ Arrhythm Electrophysiol 2021 01 14;14(1):e009260. Epub 2021 Jan 14.

Bordeaux University Hospital (CHU), Cardio-Thoracic Unit, F-33600 Pessac, France (T.C., H.M., S.B., N.W., S.P., M.H., P.B.).

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http://dx.doi.org/10.1161/CIRCEP.120.009260DOI Listing
January 2021

Progressive implantable cardioverter-defibrillator therapies for ventricular tachycardia: The efficacy and safety of multiple bursts, ramps, and low-energy shocks.

Heart Rhythm 2020 12 30;17(12):2072-2077. Epub 2020 Jul 30.

Cardio-Thoracic Unit, Bordeaux University Hospital (CHU), Pessac, France; IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac-Bordeaux, France.

Background: The Heart Rhythm Society, the European Heart Rhythm Association, the Asia Pacific Heart Rhythm Society, the Latin American Heart Rhythm Society expert consensus statement on optimal implantable cardioverter-defibrillator programming recommends burst antitachycardia pacing (ATP) for the treatment of ventricular tachycardia (VT) up to high rates. The number of bursts is not specified, and treatment by ramps or low-energy shocks is not recommended.

Objectives: We investigated the efficacy and safety of progressive therapies for VTs between 150 and 200 beats/min. After 3 failed bursts, we compared 3 ramps vs 3 bursts followed by a low-energy shock vs high-energy shock.

Methods: Using remote monitoring, we included monomorphic VT episodes treated with ≥1 burst.

Results: A total of 1126 VT episodes were included. A single burst was as likely to terminate VT between 150 and 200 beats/min as VT between 200 and 230 beats/min (63% vs 64%; P=.41), but was more likely to accelerate the latter (3.2% vs 0.25%; P<.01). For VT <200 beats/min, the likelihood of ATP success increased progressively (73% with 2 bursts, 78% with 3 bursts). Three additional bursts further increased VT termination to 89%, similar to the success rate with 3 additional ramps (88%; P=.17). Programming 6 bursts is associated with the probability of acceleration requiring shock of 6.6%. A low-energy first shock was less successful than a high-energy shock (66% vs 86%; P<.01) and more likely to accelerate VT (17% vs 0%; P<.01).

Conclusion: Programming up to 6 burst ATP therapies for VTs 150-200 beats/min can avoid implantable cardioverter-defibrillator shocks in most patients. Ramp ATP after failed bursts were similarly effective. Low-energy shocks are less effective and more arrhythmogenic than high-energy shocks.
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http://dx.doi.org/10.1016/j.hrthm.2020.07.032DOI Listing
December 2020

Should we still monitor QTc duration in frail older patients on low-dose haloperidol? A prospective observational cohort study.

Age Ageing 2020 08;49(5):829-836

Cardiology Department, Maastricht University Medical Centre, Maastricht 6229 HX, The Netherlands.

Background: Haloperidol at high dosage is associated with QTc prolongation and polymorphic ventricular arrhythmia but the effects of low-dose haloperidol remain unknown.

Objective: To evaluate the effects of low-dose haloperidol on QTc-duration in frail hospitalized elderly patients with delirium.

Methods: A prospective observational study including hospitalized patients aged ≥70 years with Groningen Frailty Index-score > 3. We included 150 patients who received haloperidol and 150 age- and frailty-matched control patients. Serial ECG recordings were performed at hospital admission and during hospitalization. QT-interval was corrected according to Framingham (QTc). Patients were grouped according to baseline QTc in normal (nQTc), borderline (bQTc) or abnormal (aQTc). Primary outcome was change in QTc-duration between first and second ECG. Potentially dangerous QTc was defined as QTc >500 ms or an increase of >50 ms.

Results: Patients in the haloperidol group (48% male, mean age 85y, nQT n = 98, bQT n = 31, aQT n = 20) received an average dose of 1.5 mg haloperidol per 24 hours. QTc decreased in patients with borderline (mean - 15 ± 29 ms, P < 0.05) or abnormal (-19 ± 27 ms, P < 0.05) QTc at baseline, no patients developed dangerous QTc-duration. In the control group (41% male, mean age 84y, nQT n = 99 bQT n = 29, aQT n = 22) QTc decreased to a similar extent (bQT -7 ± 16 ms, aQTc -23 ± 20 ms).

Conclusion: A trend to QTc shortening was seen, especially in patients with borderline or abnormal QTc at baseline, regardless of haloperidol use. These findings suggest that ECG monitoring of frail elderly patients who receive low-dose haloperidol, may not be necessary.
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http://dx.doi.org/10.1093/ageing/afaa066DOI Listing
August 2020

Validating QT-Interval Measurement Using the Apple Watch ECG to Enable Remote Monitoring During the COVID-19 Pandemic.

Circulation 2020 07 1;142(4):416-418. Epub 2020 Jun 1.

Bordeaux University Hospital (CHU), Cardio-Thoracic Unit, Pessac, France (M.S., T.C., F.D.R., S.A.-A., H.M., N.W., P.R., M.H., S.P., P.B.).

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http://dx.doi.org/10.1161/CIRCULATIONAHA.120.048253DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7382529PMC
July 2020

Electrogram morphology discriminators in implantable cardioverter defibrillators: A comparative evaluation.

J Cardiovasc Electrophysiol 2020 06 7;31(6):1493-1506. Epub 2020 May 7.

Cardio-Thoracic Unit, Bordeaux University Hospital (CHU), Pessac, France.

Background: Morphology algorithms are currently recommended as a standalone discriminator in single-chamber implantable cardioverter defibrillators (ICDs). However, these proprietary algorithms differ in both design and nominal programming.

Objective: To compare three different algorithms with nominal versus advanced programming in their ability to discriminate between ventricular (VT) and supraventricular tachycardia (SVT).

Methods: In nine European centers, VT and SVTs were collected from Abbott, Boston Scientific, and Medtronic dual- and triple-chamber ICDs via their respective remote monitoring portals. Percentage morphology matches were recorded for selected episodes which were classified as VT or SVT by means of atrioventricular comparison. The sensitivity and related specificity of each manufacturer discriminator was determined at various values of template match percentage from receiving operating characteristics (ROC) curve analysis.

Results: A total of 534 episodes were retained for the analysis. In ROC analyses, Abbott Far Field MD (area under the curve [AUC]: 0.91; P < .001) and Boston Scientific RhythmID (AUC: 0.95; P < .001) show higher AUC than Medtronic Wavelet (AUC: 0.81; P < .001) when tested for their ability to discriminate VT from SVT. At nominal % match threshold all devices provided high sensitivity in VT identification, (91%, 100%, and 90%, respectively, for Abbott, Boston Scientific, and Medtronic) but contrasted specificities in SVT discrimination (85%, 41%, and 62%, respectively). Abbott and Medtronic's nominal thresholds were similar to the optimal thresholds. Optimization of the % match threshold improved the Boston Scientific specificity to 79% without compromising the sensitivity.

Conclusion: Proprietary morphology discriminators show important differences in their ability to discriminate SVT. How much this impact the overall discrimination process remains to be investigated.
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http://dx.doi.org/10.1111/jce.14518DOI Listing
June 2020

Causes of impaired biventricular pacing in cardiac resynchronization devices with left ventricular sensing.

Pacing Clin Electrophysiol 2020 03 17;43(3):332-340. Epub 2020 Feb 17.

Bordeaux University Hospital (CHU), Cardio-Thoracic Unit, Pessac, France.

Background: Loss of biventricular stimulation can result in nonresponse to cardiac resynchronization therapy (CRT). Problems associated with the left ventricular (LV) lead and LV sensing can be challenging to detect and their incidence is unclear. The purpose of this study was to investigate mechanisms of loss of biventricular pacing due to LV lead- and LV sensing-associated problems.

Methods: In this bicentric study, CRT patients were surveilled using a novel remote monitoring algorithm from Biotronik (Germany) that registers LV electrograms (EGMs) during intermittent loss of resynchronization. The episodes were analyzed to assess the mechanisms of resynchronization interruptions.

Results: We analyzed 582 EGMs from 61 patients. During a median follow-up of 6 months, 59% of the patients had such episodes. The majority of the episodes (61%) were related to inappropriate inhibition of LV pacing, mostly due to upper rate lock-in caused by LV sensing (58%). In contrast, 8% of episodes showed intermittent loss of LV capture, which was identified thanks to LV sensing. The remaining 31% of episodes were due to physiological reasons for resynchronization interruptions (eg, supraventricular tachycardia [18%], premature beats [8%], and others [5%]). Patients with CRT interruption episodes had lower resynchronization rates (median: 98.5% vs 100%, P = .044).

Conclusions: Inadequate programming (active LV sensing with T-wave protection) is the main cause of impaired resynchronization in devices with LV sensing. In general, we recommend the deactivation of the LV T-wave protection function.
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http://dx.doi.org/10.1111/pace.13883DOI Listing
March 2020

Impedance in the Diagnosis of Lead Malfunction.

Circ Arrhythm Electrophysiol 2020 02 27;13(2):e008092. Epub 2020 Jan 27.

Division of Cardiology, VCU School of Medicine, Richmond, VA (J.N.K., K.A.E.).

Impedance is the ratio of voltage to current in an electrical circuit. Cardiovascular implantable electronic devices measure impedance to assess the structural integrity electrical performance of leads, typically using subthreshold pulses. We review determinants of impedance, how it is measured, variation in clinically measured pacing and high-voltage impedance and impedance trends as a diagnostic for lead failure and lead-device connection problems. We consider the differential diagnosis of abnormal impedance and the approach to the challenging problem of a single, abnormal impedance measurement. Present impedance provides a specific but insensitive diagnostic. For pacing circuits, we review the complementary roles of impedance and more sensitive oversensing diagnostics. Shock circuits lack a sensitive diagnostic. This deficiency is particularly important for insulation breaches, which may go undetected and present with short circuits during therapeutic shocks. We consider new methods for measuring impedance that may increase sensitivity for insulation breaches.
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http://dx.doi.org/10.1161/CIRCEP.119.008092DOI Listing
February 2020

Impact of paced left ventricular dyssynchrony on left ventricular reverse remodeling after cardiac resynchronization therapy.

J Cardiovasc Electrophysiol 2020 02 15;31(2):494-502. Epub 2020 Jan 15.

Division of Cardiology, Cliniques Universitaires Saint-Luc, Université Catholique de Louvain, Brussels, Belgium.

Introduction: We investigated whether pacing-induced electrical dyssynchrony at the time of cardiac resynchronization therapy (CRT) device implantation was associated with chronic CRT response.

Methods And Results: We included a total of 69 consecutive heart failure patients who received a CRT device. Left (LVp-RVs) and right (RVp-LVs) pacing-induced interlead delays were measured intraoperatively and used to determine if there was paced left ventricular (LV) dyssynchrony, defined as present when LVp-RVs is larger than RVp-LVs. CRT response was defined as a reduction in LV end-systolic volume ≥15%, 6 months after implantation. Paced left ventricular dyssynchrony (PLVD) was associated with ischemic cardiomyopathy (ICM) (χ : 8; P = .005) but not with QRS morphology nor with pacing lead positions. In a univariate analysis, PLVD (odds ratio [OR], 6.53; 95% confidence interval [CI], 2.2-18.9; P = .001), atypical left bundle branch block (LBBB) (OR, 3.3; 95% CI, 1.2-9.4; P = .022), and ICM (OR, 5.2; 95% CI, 1.6-17; P = .006) were associated with nonresponse. In a multivariate analysis, both PLVD (OR, 9.74; 95% CI, 2.8-33.9; P < .0001) and atypical LBBB (OR, 5.6; 95% CI, 1.5-20.3; P = .009) were independently associated with nonresponse. Adding PLVD to a model based on QRS morphology provided a significant and meaningful incremental value to predict LV reverse remodeling after CRT (χ to enter: 8; P < .005). Computer simulations corroborate these findings by showing that, while intrinsic electrical dyssynchrony is a prerequisite, the level of pacing-induced dyssynchrony modulates acute CRT response.

Conclusion: In addition to the intrinsic electrical substrate, PLVD is strongly associated with less LV reverse remodeling, demonstrating that measuring the electrical substrate during pacing has additional value for prediction of CRT response in an already well-selected patient population.
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http://dx.doi.org/10.1111/jce.14330DOI Listing
February 2020

Reply to the Editor-S-ICD oversensing: A fork in the road.

Heart Rhythm 2020 May 23;17(5 Pt A):838. Epub 2019 Nov 23.

Cardio-Thoracic Unit, Bordeaux University Hospital, Pessac, France.

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http://dx.doi.org/10.1016/j.hrthm.2019.11.022DOI Listing
May 2020

New-Onset Left Bundle Branch Block After TAVI has a Deleterious Impact on Left Ventricular Systolic Function.

Can J Cardiol 2019 10 14;35(10):1386-1393. Epub 2019 May 14.

Department of Cardiology, CHU Clermont-Ferrand, Clermont-Ferrand, France and Université Clermont Auvergne, CHU Clermont-Ferrand, CNRS, SIGMA Clermont, Institut Pascal, Clermont-Ferrand, France; INI-CRCT F-CRIN, Nancy, France.

Background: Transcatheter aortic valve implantation (TAVI) has revolutionized the management of severe aortic stenosis. The development of a new-onset complete left bundle branch block (LBBB) is, however, a frequent complication. The objective of the present study was to assess the impact of a new-onset LBBB after TAVI on the evolution of left ventricular ejection fraction (LVEF).

Methods: Forty consecutive patients were included after the development of a new-onset LBBB after TAVI and were matched for age and LVEF with 40 patients implanted during the same period who did not develop an LBBB. The primary endpoint was evolution of the LVEF measured by echocardiography before implantation and between 6 and 12 months after TAVI.

Results: The development of an LBBB was associated with a 5-point decrease in LVEF [-12.5; 2.5], contrary to the non-LBBB group (1.5 [-6.5; 9.5], P = 0.007) at 8 months, with the persistence of the LBBB (n = 23) exacerbating this decrease (-7 [-13; 2], P = 0.009). When left ventricular dysfunction (LVEF < 50%) was present before TAVI, the appearance of an LBBB was associated with a reduction in LVEF (-2 [-8; 2]) contrary to the non-LBBB group (20 [9; 22], P = 0.02).

Conclusions: The appearance of a new-onset LBBB after TAVI has a pejorative impact on left ventricular systolic function, particularly in patients with an initial LVEF < 50%, due to a lack of recovery of the latter, thereby potentially affecting their prognosis.
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http://dx.doi.org/10.1016/j.cjca.2019.05.012DOI Listing
October 2019

Very-late onset twiddler syndrome as an unusual cause of syncope.

J Interv Card Electrophysiol 2019 Dec 24;56(3):359-360. Epub 2019 Aug 24.

Cardio-Thoracic Unit, Bordeaux University Hospital (CHU), Pessac, France.

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http://dx.doi.org/10.1007/s10840-019-00613-zDOI Listing
December 2019

Oversensing issues leading to device extraction: When subcutaneous implantable cardioverter-defibrillator reached a dead-end.

Heart Rhythm 2020 01 8;17(1):66-74. Epub 2019 Jul 8.

Bordeaux University Hospital, Cardio-Thoracic Unit, Pessac, France; IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac - Bordeaux, France.

Background: Subcutaneous implantable cardioverter-defibrillator (S-ICD) implantations are rapidly expanding. However, the subcutaneous detection and interpretation of cardiac signals in S-ICDs is much more challenging than by conventional devices. There is a complete paradigm shift in cardiac signal sensing with subcutaneous signal detection, leading in some cases to oversensing with restricted programming options.

Objectives: The aim of this single-center study was to quantify and describe cases where recurring oversensing made the extraction of the device necessary.

Methods: Consecutive patients (n = 108) implanted with an S-ICD in our tertiary referral hospital were considered for analysis. Clinical and remote monitoring data were analyzed.

Results: The S-ICD had to be explanted in 6 of 108 implanted patients (5.6%) because of refractory oversensing issues: myopotential oversensing, P- or T-wave oversensing, rate-dependent left bundle branch block aberrancy during exercise with R-wave double counting, and R-wave amplitude decrease after ventricular tachycardia ablation leading to noise detection. Seventeen of 108 patients experienced oversensing (15.7%): 9 patients had at least 1 inappropriate charge without a shock (8.3%), 3 patients had at least 1 inappropriate shock (2.8%), and 5 patients had both episodes (4.6%).

Conclusion: So far, cardiologists have had to deal with transvenous ICD lead fractures, but signal oversensing without correcting programming option could be the equivalent weakness of S-ICDs, despite an adequate screening.
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http://dx.doi.org/10.1016/j.hrthm.2019.07.004DOI Listing
January 2020

Left ventricular sensing in cardiac resynchronization devices-opportunities and pitfalls for device programming.

J Cardiovasc Electrophysiol 2019 08 4;30(8):1352-1361. Epub 2019 Jul 4.

Dept. of Cardiology, Cardiothoracic Unit, Bordeaux University Hospital (CHU), Pessac, France.

Introduction: Some cardiac resynchronization therapy (CRT) device manufacturers (Biotronik, Germany; Boston Scientific, United States) have implemented left ventricular (LV) sensing functionality to prevent pacing into the vulnerable phase. Physicians are only partially aware of programming pitfalls related to LV sensing and general programming advice is lacking.

Methods And Results: We provide an illustrative case-series-based review of the variety of potential problems with LV sensing. LV sensing may inappropriately impair CRT delivery due to LV-sensing issues or improper device programming. This can cause beat-wise loss of resynchronization but also ongoing desynchronization. On the other hand, LV sensing provides additional diagnostic information, which may reveal intermittent problems of the LV lead such as capture loss. We summarize the available evidence to provide manufacturer-specific recommendations on device programming and troubleshooting for daily clinical practice.

Conclusion: CRT devices with LV sensing may suffer from impaired resynchronization due to programming pitfalls. If LV sensing is active (nominal setting in Biotronik and Boston Scientific devices), careful lookout for related problems and resynchronization percentage is required. Optimization is mandatory and even deactivation of LV sensing may have to be considered.
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http://dx.doi.org/10.1111/jce.14039DOI Listing
August 2019

Non-invasive cardiac mapping for non-response in cardiac resynchronization therapy.

Ann Med 2019 03 23;51(2):109-117. Epub 2019 May 23.

a IHU Liryc , Electrophysiology and Heart Modeling Institute , Bordeaux , France.

Cardiac resynchronization therapy (CRT) is an effective intervention in selected patients with moderate-to-severe heart failure with reduced ejection fraction and abnormal left ventricular activation time. The non-response rate of approximately 30% has remained nearly unchanged since this therapy was introduced 25 years ago. While intracardiac mapping is widely used for diagnosis and guidance of therapy in patients with tachyarrhythmia, its application in characterization of the electrical substrate to elucidate the mechanisms involved in CRT response remain anecdotal. In the present review, we describe the traditional determinants of CRT response before presenting novel non-invasive techniques used for CRT optimization. We discuss efforts to identify the target electrical substrate to guide the deployment of pacing electrodes during the operative procedure. Non-invasive body surface mapping technologies such as ECG imaging or ECG belt enables prediction of acute and chronic CRT response. While electrical dyssynchrony parameters provide high predictive accuracy for CRT response when obtained during intrinsic conduction, their predictive value is less when acquired during CRT or LV-pacing. Key messages Classic predictors of CRT response are female gender, NYHA class ≤ III, left ventricular ejection fraction ≥25%, QRS duration ≥150 ms and estimated glomerular filtration rate ≥60 mL/min. ECG-imaging is a comprehensive non-invasive mapping system which allows to express the amount of electrical asynchrony of a CRT candidate. Non-invasive body surface mapping technologies enables excellent prediction of acute and chronic CRT response before implantation. When performed during CRT or LV-pacing, the added value of these mapping systems remains unclear.
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http://dx.doi.org/10.1080/07853890.2019.1616109DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7857455PMC
March 2019

Low fibrosis biomarker levels predict cardiac resynchronization therapy response.

Sci Rep 2019 04 15;9(1):6103. Epub 2019 Apr 15.

Cardiology Department, CHU Clermont-Ferrand, Clermont-Ferrand, France.

Cardiac fibrosis is associated with heart failure and poor prognosis. Fibrosis biomarkers have been poorly evaluated as a tool to predict cardiac resynchronization therapy (CRT) response generating conflicting results. The present study assessed the predictive value of cardiac fibrosis biomarkers on CRT response. Patients underwent clinical examination, echocardiography and blood fibrosis biomarker evaluation prior to CRT implantation. At six months, a positive response to CRT was defined by a composite endpoint of no death or hospitalization for heart failure, and presence of left ventricular (LV) reverse remodeling (decrease in LV end-systolic volume ≥15%). Sixty patients were included in a multicenter study. At 6 months, 38 were positive responders to CRT and reached the response criteria (63%). Compared to non-responders, CRT responders displayed lower concentration levels of the fibrosis biomarkers procollagen type I C-terminal propeptide [PICP 135[99-166] ng/ml vs. 179[142-226]ng/ml, p = 0.001)] and procollagen type III N-terminal propeptide [PIIINP 5.50[3.66-8.96] ng/ml vs. 8.01[5.01-11.86]ng/ml, p = 0.014)] at baseline. In multivariate analysis, a PICP ≤ 163 ng/ml was associated with a positive CRT response [OR = 7.8(1.3-46.7), p = 0.023] independently of the presence of LBBB, QRS duration, LV lead position or non-ischemic cardiomyopathy. Altogether, the present findings show that a lower degree of cardiac fibrosis is associated with a positive response after CRT implantation. PICP evaluation before CRT implantation could help improve patient selection.
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http://dx.doi.org/10.1038/s41598-019-42468-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6465309PMC
April 2019

Inappropriate disabling of an ICD noise-detection algorithm in pacemaker-dependent patients.

Pacing Clin Electrophysiol 2019 Apr 12;42(4):478-482. Epub 2018 Dec 12.

Cardio-thoracic Unit, Bordeaux University Hospital (CHU), Pessac, France.

SecureSense is an implantable cardioverter defibrillator algorithm that differentiates lead-related oversensing from ventricular tachycardia/ventricular fibrillation by continuous comparison between the near-field (NF) and the far-field (FF) electrogram. If lead noise is identified, inappropriate therapy is withheld. Undersensing on the FF channel could result in inappropriate inhibition of life-saving therapy. Thus, the device automatically switches SecureSense to passive mode if undersensing on the FF channel is suspected. We report here the first cases of inappropriate automatic SecureSense deactivation due to misdiagnosed FF undersensing in pacemaker-dependent patients. Physicians should be aware that SecureSense does not withhold an inappropriate therapy for sustained oversensing in pacemaker-dependent patients.
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http://dx.doi.org/10.1111/pace.13564DOI Listing
April 2019

Unexpected and undesired side-effects of pacing algorithms during exercise.

J Electrocardiol 2018 Nov - Dec;51(6):1023-1028. Epub 2018 Aug 17.

IHU Liryc, Electrophysiology and Heart Modeling Institute, fondation Bordeaux Université, F-33600 Pessac-Bordeaux, France; Bordeaux University Hospital (CHU), Cardio-Thoracic Unit, F-33600 Pessac, France.

While the implantable pacemaker has initially been developed to treat symptomatic bradycardia, we demand of modern devices that they also function properly during exercise. In recent years, device manufacturers have implemented multiple proprietary algorithms which aim to improve pacemaker function by avoiding unnecessary right ventricular pacing, optimizing atrial refractory periods and diagnosing pacemaker mediated tachycardia. When activated, these algorithms may save the associated EGM into the device memory which enables later analysis by remote monitoring or device interrogation. In addition, the performance of an exercise-test while analyzing the EGM, enables the verification of proper algorithm function, the evaluation of residual symptoms and the optimization of specific parameters that vary as a function of heart rate. In this manuscript, we demonstrate how pacemaker algorithms may induce dropped P-waves during exercise in pacemaker dependent patients and loss of biventricular pacing in CRT patients.
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http://dx.doi.org/10.1016/j.jelectrocard.2018.08.021DOI Listing
October 2019

Reducing right ventricular pacing burden: algorithms, benefits, and risks.

Europace 2019 Apr;21(4):539-547

Lenon H. Charney Devision of Cardiology, Cardiac Electrophysiology, NYU Langone Health, New York University School of Medicine, NY, USA.

Algorithms designed to reduce the burden of right ventricular pacing are widely available in modern implantable pacing devices. To ensure safe and optimal utilization, understanding the properties of these algorithms as well as their possible unfavourable effects is essential. In this review, we discuss in detail the technical and clinical aspects of rhythm management algorithms and update on their significant recent modifications. In addition, we highlight possible adverse phenomena that may be induced by these different pacing algorithms intended to minimize pacing.
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http://dx.doi.org/10.1093/europace/euy263DOI Listing
April 2019

Performance and limitations of noninvasive cardiac activation mapping.

Heart Rhythm 2019 03 26;16(3):435-442. Epub 2018 Oct 26.

IHU LIRYC, Bordeaux University, Bordeaux, France.

Background: Activation mapping using noninvasive electrocardiographic imaging (ECGi) has recently been used to describe the physiology of different cardiac abnormalities. These descriptions differ from prior invasive studies, and both methods have not been thoroughly confronted in a clinical setting.

Objective: The goal of the present study was to provide validation of noninvasive activation mapping in a clinical setting through direct confrontation with invasive epicardial contact measures.

Methods: Fifty-nine maps were obtained in 55 patients and aligned on a common geometry. Nearest-neighbor interpolation was used to avoid map smoothing. Quantitative comparison was performed by computing between-map correlation coefficients and absolute activation time errors.

Results: The mean activation time error was 20.4 ± 8.6 ms, and the between-map correlation was poor (0.03 ± 0.43). The results suggested high interpatient variability (correlation -0.68 to 0.82), wide QRS patterns, and paced rhythms demonstrating significantly better mean correlation (0.68 ± 0.17). Errors were greater in scarred regions (21.9 ± 10.8 ms vs 17.5 ± 6.7 ms; P < .01). Fewer epicardial breakthroughs were imaged using noninvasive mapping (1.3 ± 0.5 vs 2.3 ± 0.7; P < .01). Primary breakthrough locations were imaged 75.7 ± 38.1 mm apart. Lines of conduction block (jumps of ≥50 ms between contiguous points) due to structural anomalies were recorded in 27 of 59 contact maps and were not visualized at these same sites noninvasively. Instead, artificial lines appeared in 33 of 59 noninvasive maps in regions of reduced bipolar voltage amplitudes (P = .03). An in silico model confirms these artificial constructs.

Conclusion: Overall, agreement of ECGi activation mapping and contact mapping is poor and heterogeneous. The between-map correlation is good for wide QRS patterns. Lines of block and epicardial breakthrough sites imaged using ECGi are inaccurate. Further work is required to improve the accuracy of the technique.
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http://dx.doi.org/10.1016/j.hrthm.2018.10.010DOI Listing
March 2019

Early Diagnosis of Defibrillation Lead Dislodgement.

JACC Clin Electrophysiol 2018 08 2;4(8):1075-1088. Epub 2018 May 2.

Cardiac Electrophysiology, Cedars-Sinai Heart Center, Cedars-Sinai Medical Center, Los Angeles California. Electronic address:

Objectives: This study sought to develop and evaluate an algorithm for early diagnosis of dislodged implantable cardioverter-defibrillator (ICD) leads.

Background: Dislodged defibrillation leads may sense atrial and ventricular electrograms (EGMs), triggering shocks in the vulnerable period that induce ventricular fibrillation (VF).

Methods: We developed a 2-step algorithm by using experimental lead dislodgements (LDs) at ICD implantation and a control dataset of newly implanted, in situ leads. Step 1 consisted of an alert triggered by abrupt decrease in R-wave amplitude and increase in pacing threshold. Step 2 withheld therapy based on ventricular EGM evidence of LD identified from experimental LD behavior. We estimated the algorithm's performance using a registry dataset of 3,624 new implantations and an atrial dislodgement dataset of 14 LDs at the atrium.

Results: In the registry dataset, the algorithm identified 20 of 21 radiographic LDs (95%) at a median of 11 days before clinical diagnosis. Step 1 had positive predictive values of 57% for radiographic LD and 77% for surgical revision. The false positive rate was 0.4% after step 1 and ≤0.2% after step 2. In the atrial dislodgement dataset, step 1 identified all 14 LDs; step 2 would have prevented inappropriate therapy in all 7 patients with stored EGMs at LD, including 2 patients with fatal, shock-induced VF.

Conclusions: An ICD algorithm can facilitate early diagnosis of defibrillation LD. Additional data are needed to determine the safety of withholding shocks based on EGM evidence of LD.
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http://dx.doi.org/10.1016/j.jacep.2018.03.015DOI Listing
August 2018

Cardiac Rhythm Disturbances in Hemodialysis Patients: Early Detection Using an Implantable Loop Recorder and Correlation With Biological and Dialysis Parameters.

JACC Clin Electrophysiol 2018 03 27;4(3):397-408. Epub 2017 Sep 27.

Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France; Unité INSERM 1026, Universite de Bordeaux, Bordeaux, France.

Objectives: The aim of this study was to identify using implantable loop recorder (ILR) monitoring the mechanisms leading to sudden death (SD) in patients undergoing hemodialysis (HD).

Background: SD accounts for 11% to 25% of death in HD patients.

Methods: Continuous rhythm monitoring was performed using the remote monitoring capability of the ILR device in patients undergoing HD at 8 centers. Clinical, biological, and technical HD parameters were recorded and analyzed.

Results: Seventy-one patients (mean age 65 ± 9 years, 73% men) were included. Left ventricular ejection fraction was <50% in 16%. Twelve patients (17%) had histories of atrial fibrillation or flutter at inclusion. During a mean follow-up period of 21.3 ± 6.9 months, 16 patients died (14% patient-years), 7 (44%) of cardiovascular causes. Four SDs occurred, with progressive bradycardia followed by asystole. The incidence of patients presenting with significant conduction disorder and with ventricular arrhythmia was 14% and 9% patient-years, respectively. In multivariate survival frailty analyses, a higher risk for conduction disorder was associated with plasma potassium >5.0 mmol/l, bicarbonate <22 mmol/l, hemoglobin >11.5 g/dl, pre-HD systolic blood pressure >140 mm Hg, the longer interdialytic period, history of coronary artery disease, previous other arrhythmias, and diabetes mellitus. A higher risk for ventricular arrhythmia was associated with potassium <4.0 mmol/l, no antiarrhythmic drugs, and previous other arrhythmias. With ILR monitoring, de novo atrial fibrillation or flutter was diagnosed in 14 patients (20%).

Conclusions: ILR may be considered in HD patients prone to significant conduction disorders, ventricular arrhythmia, or atrial fibrillation or flutter to allow early identification and initiation of adequate treatment. Therapeutic strategies reducing serum potassium variability could decrease the rate of SD in these patients. (Implantable Loop Recorder in Hemodialysis Patients [RYTHMODIAL]; NCT01252823).
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http://dx.doi.org/10.1016/j.jacep.2017.08.002DOI Listing
March 2018

Localized Structural Alterations Underlying a Subset of Unexplained Sudden Cardiac Death.

Circ Arrhythm Electrophysiol 2018 07;11(7):e006120

IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, France (M. Haïssaguerre, M. Hocini, G.C., J.D., F.S., S.P., H.C., M.T., A.D., R.M., N.D., P.B., P.R., S.P., T.P., N.K., G.M., X.P., C.D., L.L., R.C., P.J., D.B., E.V., M.P., R.W., O.B., R.D.).

Background: Sudden cardiac death because of ventricular fibrillation (VF) is commonly unexplained in younger victims. Detailed electrophysiological mapping in such patients has not been reported.

Methods: We evaluated 24 patients (29±13 years) who survived idiopathic VF. First, we used multielectrode body surface recordings to identify the drivers maintaining VF. Then, we analyzed electrograms in the driver regions using endocardial and epicardial catheter mapping during sinus rhythm. Established electrogram criteria were used to identify the presence of structural alterations.

Results: VF occurred spontaneously in 3 patients and was induced in 16, whereas VF was noninducible in 5. VF mapping demonstrated reentrant and focal activities (87% versus 13%, respectively) in all. The activities were dominant in one ventricle in 9 patients, whereas they had biventricular distribution in others. During sinus rhythm areas of abnormal electrograms were identified in 15/24 patients (62.5%) revealing localized structural alterations: in the right ventricle in 11, the left ventricle in 1, and both in 3. They covered a limited surface (13±6 cm) representing 5±3% of the total surface and were recorded predominantly on the epicardium. Seventy-six percent of these areas were colocated with VF drivers (<0.001). In the 9 patients without structural alteration, we observed a high incidence of Purkinje triggers (7/9 versus 4/15, =0.033). Catheter ablation resulted in arrhythmia-free outcome in 15/18 patients at 17±11 months follow-up.

Conclusions: This study shows that localized structural alterations underlie a significant subset of previously unexplained sudden cardiac death. In the other subset, Purkinje electrical pathology seems as a dominant mechanism.
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http://dx.doi.org/10.1161/CIRCEP.117.006120DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7661047PMC
July 2018

Response to cardiac resynchronization therapy is determined by intrinsic electrical substrate rather than by its modification.

Int J Cardiol 2018 Nov 6;270:143-148. Epub 2018 Jun 6.

IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, F-33600 Pessac, Bordeaux, France; Bordeaux University Hospital (CHU), Cardio-Thoracic Unit, F-33600 Pessac, France.

Background: Electrocardiographic mapping (ECM) expresses electrical substrate through magnitude and direction of the activation delay vector (ADV). We investigated to what extent the response to cardiac resynchronization therapy (CRT) is determined by baseline ADV and by ADV modification through CRT and optimization of left ventricular (LV) pacing site.

Methods: ECM was performed in 79 heart failure patients (4 RBBB, 12 QRS < 120 ms, 23 non-specific conduction delay [NICD] and 40 left bundle branch block [LBBB]). 67 patients (QRS ≥ 120 ms) underwent CRT implantation and in 26 patients multiple LV pacing site optimization was performed. ADV was calculated from locations/depolarization times of 2000 virtual epicardial electrodes derived from ECM. Acute response was defined as ≥10% LVdP/dt increase, chronic response by composite clinical score at 6 months.

Results: During intrinsic conduction, ADV direction was similar in patients with QRS < 120 ms, NICD and LBBB, pointing towards the LV free wall, while ADV magnitude was larger in LBBB (117 ± 25 ms) than in NICD (70 ± 29 ms, P < 0.05) and QRS < 120 ms (52 ± 14 ms, P < 0.05). Intrinsic ADV accurately predicted the acute (AUC = 0.93) and chronic (AUC = 0.90) response to CRT. ADV change by CRT only moderately predicted response (highest AUC = 0.76). LV pacing site optimization had limited effects: +3 ± 4% LVdP/dt when compared to conventional basolateral LV pacing.

Conclusion: The baseline electrical substrate, adequately measured by ADV amplitude, strongly determines acute and chronic CRT response, while the extent of its modification by conventional CRT or by varying LV pacing sites has limited effects.
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http://dx.doi.org/10.1016/j.ijcard.2018.06.005DOI Listing
November 2018

Towards eradication of inappropriate therapies for ICD lead failure by combining comprehensive remote monitoring and lead noise alerts.

J Cardiovasc Electrophysiol 2018 08 22;29(8):1125-1134. Epub 2018 Jun 22.

IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, F-33600, Pessac- Bordeaux, France.

Introduction: Recognition of implantable cardioverter defibrillator (ICD) lead malfunction before occurrence of life threatening complications is crucial. We aimed to assess the effectiveness of remote monitoring associated or not with a lead noise alert for early detection of ICD lead failure.

Methods: From October 2013 to April 2017, a median of 1,224 (578-1,958) ICD patients were remotely monitored with comprehensive analysis of all transmitted materials. ICD lead failure and subsequent device interventions were prospectively collected in patients with (RMLN) and without (RM) a lead noise alert (Abbott Secure Sense™ or Medtronic Lead Integrity Alert™) in their remote monitoring system.

Results: During a follow-up of 4,457 patient years, 64 lead failures were diagnosed. Sixty-one (95%) of the diagnoses were made before any clinical complication occurred. Inappropriate shocks were delivered in only one patient of each group (3%), with an annual rate of 0.04%. All high voltage conductor failures were identified remotely by a dedicated impedance alert in 10 patients. Pace-sense component failures were correctly identified by a dedicated alert in 77% (17 of 22) of the RMLN group versus 25% (8 of 32) of the RM group (P = 0.002). The absence of a lead noise alert was associated with a 16-fold increase in the likelihood of initiating either a shock or ATP (OR: 16.0, 95% CI 1.8-143.3; P = 0.01).

Conclusion: ICD remote monitoring with systematic review of all transmitted data is associated with a very low rate of inappropriate shocks related to lead failure. Dedicated noise alerts further reduce inappropriate detection of ventricular arrhythmias.
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http://dx.doi.org/10.1111/jce.13653DOI Listing
August 2018

Optimizing Implantable Cardioverter-Defibrillator Remote Monitoring: A Practical Guide.

JACC Clin Electrophysiol 2017 04 17;3(4):315-328. Epub 2017 Apr 17.

IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Pessac, Bordeaux, France; Bordeaux University Hospital (CHU), Cardio-Thoracic Unit, Pessac, Bordeaux, France.

Remote monitoring (RM) receives a Class I: Level of Evidence: A recommendation for the follow-up of patients with implantable cardioverter-defibrillators, positioning the technology as standard of care. RM is often seen and sold as a plug-and-play technology, whereas fundamental differences exist in the philosophy and conception of the 5 main RM systems. The capabilities and limitations of the different RM systems need to be understood and taken into account when the decision is made to remotely manage an individual patient. The purpose of this review is to provide to the cardiologist practical information about RM systems' specificities with respect to the different technical and clinical alerts. Clinically based indications and programming suggestions are provided.
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http://dx.doi.org/10.1016/j.jacep.2017.02.007DOI Listing
April 2017

Defibrillation testing is mandatory in patients with subcutaneous implantable cardioverter-defibrillator to confirm appropriate ventricular fibrillation detection.

Heart Rhythm 2018 05;15(5):642-650

Hospital Haut-Leveque, IHU LIRYC, Pessac, France.

Background: The subcutaneous implantable cardioverter-defibrillator (S-ICD) remains a new technology requiring accurate assessment of the various aspects of its functioning. Isolated cases of delayed sensing of ventricular arrhythmia have been described.

Objective: The purpose of this multicenter study was to assess the quality of sensing during induced ventricular fibrillation (VF).

Methods: One hundred thirty-seven patients underwent induction of VF at the end of the S-ICD implantation.

Results: VF induction was successful in 133 patients (97%). Mean time to first therapy was 16.2 ± 3.1 seconds, with a substantial range from 12.5 to 27.0 seconds. Four different detection profiles were arbitrarily defined: (1) optimal detection (n = 39 [29%]); (2) undersensing with moderate prolongation of time to therapy (<18 seconds; n = 68 [51%]); (3) undersensing with significant prolongation of the time to therapy (>18 seconds; n = 19 [14%]); and (4) absence of therapy or prolonged time to therapy related to noise oversensing (n = 7 [6%]). In some of the patients in the last group, despite induction of VF the initial counter was never filled, the device did not charge the capacitors, and the shock was not delivered because of a sustained diagnosis of noise (n = 5). A manual shock by the device or an external shock had to be delivered to restore the sinus rhythm.

Conclusion: Our study demonstrated a marked sensing delay leading to prolonged time to therapy in a large number of S-ICD patients. A few worrisome cases of noise oversensing inhibiting the therapies were detected. These results support the need for systematic intraoperative defibrillation testing.
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http://dx.doi.org/10.1016/j.hrthm.2018.02.013DOI Listing
May 2018

Electrical Substrates Driving Response to Cardiac Resynchronization Therapy: A Combined Clinical-Computational Evaluation.

Circ Arrhythm Electrophysiol 2018 04;11(4):e005647

Electrophysiology and Heart Modeling Institute (LIRYC), Bordeaux University, Pessac, France (P.R.H., S.P., M.S., P.R., M.H., J.L., P.B.). Cardiac Electrophysiology and Cardiac Stimulation Team, Bordeaux University Hospital, Pessac, France (P.R.H., S.P., M.S., P.R., M.H., J.L., P.B.). Cardiovascular Research Institute Maastricht (CARIM), Maastricht University Medical Center, the Netherlands (P.R.H., M.S., J.W., F.W.P., T.D., J.L.).

Background: The predictive value of interventricular versus intraventricular dyssynchrony for response to cardiac resynchronization therapy (CRT) remains unclear. We investigated the relative importance of both ventricular electrical substrate components for left ventricular (LV) hemodynamic function.

Methods And Results: First, we used the cardiovascular computational model CircAdapt to characterize the isolated effect of intrinsic interventricular and intraventricular activation on CRT response (ΔLVdP/dt). Simulated ΔLVdP/dt (range: 1.3%-26.5%) increased considerably with increasing interventricular dyssynchrony. In contrast, the isolated effect of intraventricular dyssynchrony in either the LV or right ventricle was limited (ΔLVdP/dt range: 12.3%-18.3% and 14.1%-15.7%, respectively). Effects of activation during biventricular pacing on ΔLVdP/dt were small. Second, electrocardiographic imaging-derived activation characteristics of 51 CRT candidates were used to personalize ventricular activation in CircAdapt. The individualized models were subsequently used to assess the accuracy of ΔLVdP/dt prediction based on the electrical data. The model-predicted ΔLVdP/dt was close to the actual value in patients with left bundle branch block (measured-simulated: 2.7±9.0%) when only intrinsic interventricular dyssynchrony was personalized. Among patients without left bundle branch block, ΔLVdP/dt was systematically overpredicted by CircAdapt (measured-simulated: 9.2±7.1%). Adding intraventricular activation to the model did not improve the accuracy of the response prediction.

Conclusions: Computer simulations revealed that intrinsic interventricular dyssynchrony is the dominant component of the electrical substrate driving the response to CRT. Intrinsic intraventricular dyssynchrony and any dyssynchrony during biventricular pacing play a minor role in this respect. This may facilitate patient-specific modeling for prediction of CRT response.

Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01270646.
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http://dx.doi.org/10.1161/CIRCEP.117.005647DOI Listing
April 2018