Publications by authors named "Stefan Asbach"

34 Publications

Fascicular parasystole and recurrent syncope - a case report.

Eur Heart J Case Rep 2018 Mar 5;2(1):yty020. Epub 2018 Mar 5.

Department of Cardiology and Angiology I, Heart Center Freiburg University, Hugstetter Str. 55, 79106 Freiburg, Germany.

Introduction: Parasystole refers to an ectopic pacemaker that discharges with a constant rate competing with the primary pacemaker of the heart the sinus node. Parasystolic pacemakers have been described in the atrium, atrioventricular node, His bundle, and in the ventricle. Ventricular parasystole usually carries a benign prognosis, but there are a few reports of ventricular tachyarrhythmia initiated by parasystolic beats.

Case Presentation: We present a case of a 15-year-old otherwise healthy teenager with recurrent most likely arrhythmic syncope who was diagnosed with ventricular parasystole from the left posterior fascicle. After exclusion of structural and primary electrical heart disease, the patient was deemed at increased risk of parasystole-induced tachyarrhythmia, and thus catheter ablation of the ectopic focus was performed. Since catheter ablation the patient continues to be free of any symptoms.

Discussion: This report highlights the potential risks of parasystole in context of recurrent syncope and reviews the available literature on parasystole and ventricular tachyarrhythmia.
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http://dx.doi.org/10.1093/ehjcr/yty020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6426017PMC
March 2018

Apparent pacemaker dysfunction during peptide receptor radionuclide therapy for neuroendocrine tumor.

Clin Case Rep 2018 01 14;6(1):197-199. Epub 2017 Dec 14.

Cardiology and Angiology I Heart Center Freiburg University Freiburg Germany.

This case is a reminder not to overlook rare causes of electrolyte shifts, which may cause reversible changes in pacemaker pacing thresholds.
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http://dx.doi.org/10.1002/ccr3.1271DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5771922PMC
January 2018

Automated lesion annotation during pulmonary vein isolation: influence on acute isolation rates and lesion characteristics.

J Interv Card Electrophysiol 2016 Dec 10;47(3):349-356. Epub 2016 Aug 10.

Cardiology and Angiology I, Heart Center, Freiburg University, Hugstetter Str. 55, 79106, Freiburg, Germany.

Purpose: Recovery of pulmonary vein (PV) conduction is a common mechanism of atrial fibrillation recurrence after PV isolation (PVI), underscoring the need for durable lesion formation. We aimed to evaluate the utility of an automated lesion annotation algorithm (ALAA) on acute isolation rates and resulting lesion characteristics.

Methods: Fifty patients underwent PVI using a contact force (CF) sensing catheter and ALAA. Single antral circles around ipsilateral PVs were performed with ALAA-1 settings including catheter stability (range of motion ≤2 mm, duration >10 s). Target CF was 10-20 g but not part of ALAA-1 settings. If PV conduction persisted after circle completion, force over time was added to automated settings (ALAA-2). Emerging gaps were subsequently ablated, followed by re-assessment for PVI.

Results: ALAA-1 isolated 70 % of the left and 78 % of the right PVs using 756.3 ± 212.3 s (left) and 737.1 ± 145.9 s (right) of energy delivery. ALAA-2 settings identified 29 gaps in previously unisolated PVs, closure significantly increased isolation rates to 88 % of the left and 96 % of the right PVs with additional 325.4 ± 354.1 s (left) and 266.8 ± 279.5 s (right) of energy delivery (p = 0.001). Lesion characteristics significantly differed between ALAA-1 (n = 3521 lesions) and ALAA-2 (n = 3037 lesions) settings, and between isolated and non-isolated PV segments, particularly with respect to CF. Interlesion distances with ALAA-2 were significantly longer in the left superior, left superior-anterior, and right superior-posterior segments when compared to ALAA-1.

Conclusions: Settings of an ALAA affect lesion characteristics reveal areas of insufficient lesion formation and influence acute effectiveness of PVI. Combination of CF and stability shows superior performance over stability alone.
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http://dx.doi.org/10.1007/s10840-016-0173-yDOI Listing
December 2016

Right Bundle Branch Block-Like Pattern During Uncomplicated Right Ventricular Pacing and the Effect of Pacing Site.

Am J Cardiol 2016 Mar 30;117(6):935-9. Epub 2015 Dec 30.

Deutsches Herzzentrum München, Klinik für Herz-und Kreislauferkrankungen, Abteilung für Elektrophysiologie, Faculty of Medicine, Technische Universität München, Munich, Germany.

Right bundle branch block (RBBB) configuration is an unexpected finding during right ventricular (RV) pacing that raises the suspicion of inadvertent left ventricular lead positioning. The aim of this study was to evaluate the prevalence of paced RBBB pattern in relation to RV lead location. This is a secondary analysis of a prospective, multicenter study, which randomized implantable cardioverter defibrillator recipients to an apical versus midseptal defibrillator lead positioning. A 12-lead electrocardiogram was recorded during intrinsic rhythm and RV pacing. Paced RBBB-like pattern was defined as positive (>0.05 mV) net amplitude of QRS complex in leads V1 and/or V2. In total, 226 patients (65.6 ± 12.0 years, 20.8% women, 53.1% apical site) were included in the study. The prevalence of paced RBBB pattern in the total population was 15.5%. A significantly lower percentage of patients in the midseptal group demonstrated RBBB-type configuration during RV pacing compared with the apical group (1.9% vs 27.5%, p <0.001). Baseline RBBB, prolonged QRS duration during intrinsic rhythm, and reduced ejection fraction were not associated with increased likelihood of paced RBBB. In the subgroup of patients with RBBB type during pacing, 91.4% of patients had a paced QRS axis from -30° to -90°, whereas 100% of patients displayed a negative QRS vector at lead V3. In conclusion, RBBB configuration is encountered in a considerable percentage of device recipients during uncomplicated RV pacing. Midseptal lead positioning is associated with significantly lower likelihood of paced RBBB pattern compared with apical location.
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http://dx.doi.org/10.1016/j.amjcard.2015.12.028DOI Listing
March 2016

Impact of the Right Ventricular Lead Position on Clinical End Points in CRT Recipients--A Subanalysis of the Multicenter Randomized SPICE Trial.

Pacing Clin Electrophysiol 2016 Mar 12;39(3):261-7. Epub 2016 Jan 12.

Cardiology and Angiology I, University Heart Center, Freiburg, Germany.

Background: The impact of right ventricular (RV) lead location on clinical end points in patients undergoing cardiac resynchronization therapy (CRT) is unclear. We evaluated the impact of different RV lead locations on clinical outcome in CRT patients enrolled in the Septal Positioning of ventricular implantable cardioverter-defibrillator (ICD) Electrodes (SPICE) trial, which randomized recipients of implantable cardioverter defibrillators to apical versus midseptal RV lead positioning.

Methods: Ninety-eight CRT recipients were included in the multicenter SPICE trial and followed for 12 months: Fifty-three patients were randomized to receive an apical (A) and 45 to receive a midseptal (S) lead position. We compared echocardiographical and electrocardiographical parameters and outcome.

Results: Echocardiographic response with respect to improvement of left ventricular ejection fraction (A: +15.8 ± 14.6%, S: +9.7 ± 12.6%, P = 0.156) and reduction of left ventricular end-diastolic diameter (A: -4.2 ± 10.7 mm, S: -7.5 ± 10.7 mm, P = 0.141) was comparable in apical and midseptal groups. Paced QRS width neither differed at prehospital discharge (A: 129 ± 21 ms, S: 135 ± 21 ms, P = 0.133) nor at 12-month follow-up (A: 131 ± 23 ms, S: 134 ± 28 ms, P = 0.620). No differences were found with respect to the risk of ventricular tachyarrhythmia or ICD therapy. Septal RV lead position, however, was associated with a significant longer time to a first heart failure event (P = 0.040) and a longer survival time (P = 0.019).

Conclusions: In CRT recipients, midseptal RV lead position was not superior with respect to improvement of echocardiographic parameters or paced QRS width. It did not predispose to ventricular arrhythmias or ICD therapy. The finding that midseptal lead position was associated with a longer time to first heart failure event and a longer survival time deserves further investigation.
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http://dx.doi.org/10.1111/pace.12793DOI Listing
March 2016

ICD Shock, Not Ventricular Fibrillation, Causes Elevation of High Sensitive Troponin T after Defibrillation Threshold Testing--The Prospective, Randomized, Multicentre TropShock-Trial.

PLoS One 2015 24;10(7):e0131570. Epub 2015 Jul 24.

Deutsches Herzzentrum München, Klinik für Herz- und Kreislauferkrankungen, Abteilung für Elektrophysiologie, Faculty of Medicine, Technische Universität München, Munich, Germany.

Background: The placement of an implantable cardioverter defibrillator (ICD) has become routine practice to protect high risk patients from sudden cardiac death. However, implantation-related myocardial micro-damage and its relation to different implantation strategies are poorly characterized.

Methods: A total of 194 ICD recipients (64±12 years, 83% male, 95% primary prevention of sudden cardiac death, 35% cardiac resynchronization therapy) were randomly assigned to one of three implantation strategies: (1) ICD implantation without any defibrillation threshold (DFT) testing, (2) estimation of the DFT without arrhythmia induction (modified "upper limit of vulnerability (ULV) testing") or (3) traditional safety margin testing including ventricular arrhythmia induction. High-sensitive Troponin T (hsTnT) levels were determined prior to the implantation and 6 hours after.

Results: All three groups showed a postoperative increase of hsTnT. The mean delta was 0.031±0.032 ng/ml for patients without DFT testing, 0.080±0.067 ng/ml for the modified ULV-testing and 0.064±0.056 ng/ml for patients with traditional safety margin testing. Delta hsTnT was significantly larger in both of the groups with intraoperative ICD testing compared to the non-testing strategy (p≤0.001 each). There was no statistical difference in delta hsTnT between the two groups with intraoperative ICD testing (p = 0.179).

Conclusion: High-sensitive Troponin T release during ICD implantation is significantly higher in patients with intraoperative ICD testing using shock applications compared to those without testing. Shock applications, with or without arrhythmia induction, did not result in a significantly different delta hsTnT. Hence, the ICD shock itself and not ventricular fibrillation seems to cause myocardial micro-damage.

Trial Registration: ClinicalTrials.gov NCT01230086.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0131570PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4514854PMC
May 2016

Pulmonary vein stenosis after pulmonary vein isolation using duty-cycled unipolar/bipolar radiofrequency ablation guided by intracardiac echocardiography.

J Interv Card Electrophysiol 2015 Oct 17;44(1):47-54. Epub 2015 Jun 17.

Department of Radiology, University Hospital, Freiburg, Germany.

Purpose: Concerning rates of pulmonary vein (PV) stenosis were reported following PV isolation (PVI) with a circular pulmonary vein ablation catheter (PVAC). As this may depend on intraprocedural imaging, we evaluated the incidence of PV stenosis in patients undergoing PVAC-PVI with continuous surveillance by intracardiac echocardiography (ICE).

Methods: Multi-slice computed tomography was performed before and 3 months after PVAC-PVI with continuous ICE surveillance in 30 patients (37 % male, 65 ± 9 years). PV areas at two levels (ostial and 1 cm distally) and left atrial (LA) volumes were measured. PV area/LA volume ratio was calculated to correct for reverse LA remodelling. PV stenosis was classified as mild (25-50 %), moderate (50-75 %) and severe (> 75 %).

Results: One hundred sixteen veins were isolated with PVAC with additional touch-up ablation in one patient. One patient was excluded from analysis for untriggered CT acquisition. Left atrial volume decreased from 109.1 ± 30.9 cm(3) before to 98.4 ± 34.4 cm(3) after ablation (p < 0.05). Overall, PV areas decreased ostially from 209.0 ± 80.3 mm(2) to 171.2 ± 74.6 mm(2) (p < 0.0001) and distally from 155.2 ± 61.5 mm(2) to 141.0 ± 51.3 mm(2) (p < 0.0001). After adjustment for LA volume reduction, PV area significantly reduced only at the ostial level (p = 0.0069). Mild PV stenosis (ostial/distal) was detected in 17/9 PVs (14.7 %/7.8 %) and moderate PV stenosis in 7/0 PVs (6.0 %/0 %). PV stenosis occurred more often in superior PVs (p = 0.0004). No severe PV stenosis occurred. All patients remained asymptomatic.

Conclusions: While the use of ICE does not fully prevent the occurrence of ostial PV stenosis after PVAC-PVI, no significant narrowing in distal PVs was observed. Superior PVs are prone to PV stenosis after PVAC-PVI.
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http://dx.doi.org/10.1007/s10840-015-0028-yDOI Listing
October 2015

Effectiveness and Reliability of Selected Site Pacing for Avoidance of Phrenic Nerve Stimulation in CRT Patients with Quadripolar LV Leads: The EffaceQ Study.

Pacing Clin Electrophysiol 2015 Aug 12;38(8):942-50. Epub 2015 Jun 12.

Klinikum Coburg, Coburg, Germany.

Background: Cardiac resynchronization therapy (CRT) relies on sufficient left ventricular (LV) pacing with safety margin to phrenic nerve stimulation (PNS). Previous studies introduced LV vector reprogramming in bipolar coronary sinus leads to optimize LV pacing and avoid PNS. We investigated the efficacy and reliability of quadripolar leads in CRT.

Methods: The EffaceQ study enrolled 344 patients with de novo CRT implantation with a quadripolar LV lead in an observational, prospective multicenter study. The study was powered to demonstrate that in at least 90% of patients with an implanted quadripolar LV lead, a viable LV pacing configuration (LVPC) is available (primary end point: LV pacing threshold ≤2.5 V/0.5 ms, sufficient PNS margin).

Results: Quadripolar leads were successfully implanted in 96% of patients. A total of 278 of 299 (93.0%) patients with complete data met the criteria for viable LVPC. With the use of traditional LVPCs, a viable LVPC would have been available (268 of 299 patients; P = 0.002) in significantly fewer patients (89.6%). In any LVPC, PNS was inducible in 65.0% of patients and 22.6% of patients reported PNS during ambulatory 3-month follow-up. LVPC reprogramming was performed in 49.8% of patients. PNS inducibility decreased from distal to proximal electrodes, whereas LV pacing thresholds increased from distal to proximal. At prehospital discharge, 5.9 ± 2.8 viable LVPCs were observed, stable during follow-up. The quadripolar electrode offered significantly more LVPC for LV optimization and PNS avoidance.

Conclusion: Quadripolar LV leads yield high numbers of patients with viable LVPCs and alternatives for noninvasive repositioning of LV pacing.
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http://dx.doi.org/10.1111/pace.12664DOI Listing
August 2015

Author's reply: To PMID 24895019.

Europace 2015 Jun 4;17(6):1000. Epub 2015 Mar 4.

Cardiology and Angiology I, University Heart Center, Freiburg, Germany

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http://dx.doi.org/10.1093/europace/euu400DOI Listing
June 2015

In vivo contact force measurements and correlation with left atrial anatomy during catheter ablation of atrial fibrillation.

Europace 2015 Oct 4;17(10):1526-32. Epub 2015 Mar 4.

Cardiology and Angiology I, Heart Center, Freiburg University, Freiburg, Germany

Aims: Lesion formation during catheter ablation crucially depends on catheter-tissue contact. We sought to evaluate the impact of anatomical characteristics of the left atrium (LA) and the pulmonary veins (PVs) on contact force (CF) measurements.

Methods And Results: An anatomical map of the LA was obtained in 25 patients prior to catheter ablation of atrial fibrillation. Contact force (operator blinded) and local bipolar electrogram amplitudes (EGM) were measured in eight pre-defined segments around the PVs. After unblinding, points with low CF (≤5 g) were corrected to CF >5 g, and the distance between points was measured. In a pre-procedural computed tomography of the heart, LA volume as well as sizes and circumferences of the PV ostia were measured and correlated to CF measurements. Four hundred and twenty-six points in eight pre-defined LA locations were assessed. Low CF (<5 g) was found in 25.0% (43.5%) of points superior, 33.3% (66.7%) anterior, 32.1% (44.4%) inferior, and 15.5% (15.9%) posterior to the right (left) PVs. The mean distance after correction was 5.8 ± 3.4 mm. Local bipolar electrogram amplitudes between low- and high-CF points did not differ (1.21 ± 1.54 vs. 1.13 ± 1.3 mV, P = ns). The mean CF at the left PVs was significantly lower than at the right PVs (7.91 ± 3.74 vs. 13.95 ± 6.34 g, P < 0.001), with the lowest CF anterior to the left PVs (5.2 ± 3.6 g). Contact force measurements did not correlate to LA volume, size, and circumference of the PVs.

Conclusion: Contact force during LA mapping significantly differs according to the location within the LA. These differences are independent of LA volume and anatomy of the PV ostia.
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http://dx.doi.org/10.1093/europace/euu410DOI Listing
October 2015

A stepwise electrocardiographic algorithm for differentiation of mid-septal vs. apical right ventricular lead positioning: the SPICE ECG substudy.

Europace 2015 Jun 8;17(6):915-20. Epub 2015 Jan 8.

Deutsches Herzzentrum München, Klinik für Herz- und Kreislauferkrankungen, Abteilung für Elektrophysiologie, Faculty of Medicine, Technische Universität München, Munich, Germany.

Aims: Right ventricular (RV) septum is a non-apical site targeted during lead implantation. Electrocardiographic (ECG) recognition of mid-septal lead location is challenging. The aim of the study is to determine ECG correlates of RV mid-septal pacing.

Methods And Results: The present study is a pre-specified analysis of a prospective, multicenter study, which randomized recipients of an implantable cardioverter defibrillator to an apical vs. mid-septal RV lead positioning. Following implantation, a 12-lead ECG was recorded during intrinsic rhythm and RV pacing. In total, 227 patients, 121 in the apical group (76.9% males, 67.1 ± 11.3 years) and 106 in the mid-septal group (82.1% males, age 64.7 ± 12.7 years) were included. Apically as compared with septally paced patients had significantly longer paced QRS duration (177.0 ± 25.0 vs. 170.4 ± 21.7, respectively, P = 0.03) and significantly more leftward paced QRS axis (-71.6 ± 33.3° vs. 9.4 ± 86.5°, respectively, P < 0.001). A significantly higher proportion of patients in the mid-septal as compared with the apical group displayed predominantly positive QRS in lead V6 (62.3 vs. 4.1%, P < 0.001), predominantly positive QRS in any of the inferior leads (53.8 vs. 4.1%, P < 0.001), and a QR pattern in lead aVL (53.3 vs. 3.3%, P < 0.001). These ECG correlates were incorporated in a stepwise algorithm with total sensitivity of 87% and specificity of 90% for the identification of a mid-septal lead location.

Conclusion: A mid-septal lead location may be identified using a simple stepwise algorithm, based on the presence of positive QRS in lead V6, positive QRS in any of the inferior leads, and a QR pattern in lead aVL.
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http://dx.doi.org/10.1093/europace/euu344DOI Listing
June 2015

Electrocardiographic identification of prior myocardial infarction during right ventricular pacing--effect of septal versus apical pacing.

Int J Cardiol 2014 Dec 5;177(3):977-81. Epub 2014 Oct 5.

Deutsches Herzzentrum München, Klinik für Herz- und Kreislauferkrankungen, Abteilung für Elektrophysiologie, Faculty of Medicine, Technische Universität München, Munich, Germany.

Background: Electrocardiographic (ECG) identification of prior myocardial infarction (MI) during right ventricular (RV) pacing is of clinical importance. Proposed ECG criteria have been evaluated only during apical pacing. We evaluated the effect of pacing site on the predictive performance of ECG signs of prior MI.

Methods: The present study is a secondary analysis of a prospective, multicenter study which randomized recipients of an implantable cardioverter defibrillator to an apical versus septal RV lead positioning. ECGs of patients with or without prior MI were analyzed for the presence of the following criteria: Cabrera sign, Chapman sign, QR pattern in leads I, aVL, V5 or V6, QR in inferior leads and notching in the descending slope of the QRS complex in inferior leads.

Results: The MI group included 89 patients (55.1% apically paced), while 99 patients had no prior MI (50.5% apically paced). In the total population, the Cabrera sign presented the highest specificity (97%) and diagnostic accuracy (62.2%), with a sensitivity of 23.6%. The Cabrera sign was the only significant predictor of a prior MI [OR=9.9, (95%CI:2.8-34.5), p<0.001], among all ECG markers. Pacing site did not significantly influence the sensitivity and specificity of the Cabrera sign for detection of prior MI.

Conclusions: In our study, the Cabrera sign was the only ECG marker that predicted the presence of prior MI during ventricular paced rhythm. Septal RV lead positioning did not affect the predictive performance of the Cabrera sign.
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http://dx.doi.org/10.1016/j.ijcard.2014.09.187DOI Listing
December 2014

Haemodynamic vector personalization of a quadripolar left ventricular lead used for cardiac resynchronization therapy: use of surface electrocardiogram and interventricular time delays.

Europace 2014 Oct 3;16(10):1476-81. Epub 2014 Jun 3.

Department of Cardiology and Angiology I, Heart Center, University of Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany

Aims: The choice of left ventricular pacing configurations (LVPCs) of quadripolar leads used for cardiac resynchronization therapy (CRT) affects haemodynamic response and thus may be a tool for device optimization. The value of surface electrocardiograms and interventricular time delays (IVDs) for optimization is unknown.

Methods And Results: Sixteen patients implanted with a CRT device with a quadripolar LV lead underwent invasive testing of LV dP/dt. QRS durations at baseline (bl) and during biventricular pacing (biv) were measured using different LVPCs (total of 141 LVPCs; 8.8 per patient). Variations in QRS duration during biv were calculated for each patient (ΔQRS) and, when compared with intrinsic QRS duration, for all LVPCs (ΔQRSLVPC). Interventricular time delays between the poles of the LV lead were obtained from intracardiac electrograms. ΔIVD was calculated as IVDmax - IVDmin. Parameters were correlated with LV dP/dt. ΔQRS and ΔQRSLVPC both significantly correlated with LV dP/dt (P < 0.01). Correlation was found for patients with ischaemic (P < 0.001) and non-ischaemic cardiomyopathy (P < 0.05), and for patients with bl QRS duration >168 ms (P < 0.001), but not <168 ms (P = ns). The LVPC with shortest QRS duration also yielded maximal LV dP/dt in 6 of 16 patients (37.5%), and was equal or better in LV dP/dt in 12 of 16 patients (75%). ΔIVD neither correlated with ΔQRS nor ΔLV dP/dt.

Conclusion: ΔQRS predicts the maximal value of vector personalization in the individual. Reductions in QRS width, but not IVDs, correlate with acute haemodynamic response. Intraindividually, in 75% of patients, the LVPC with the shortest QRS duration gives equal or superior haemodynamic results when compared with the LVPC with longest QRS duration.
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http://dx.doi.org/10.1093/europace/euu136DOI Listing
October 2014

Safety of mid-septal electrode placement in implantable cardioverter defibrillator recipients--results of the SPICE (Septal Positioning of ventricular ICD Electrodes) study.

Int J Cardiol 2014 Jul 26;174(3):713-20. Epub 2014 Apr 26.

Heart Centre Freiburg University, Department of Cardiology and Angiology I, Freiburg, Germany.

Background: Detrimental effects of right ventricular (RV) apical pacing have directed the interest toward alternative pacing sites such as the RV mid-septum. As safety data are scarce for implantable cardioverter defibrillator (ICD) recipients the study aims to evaluate ICD lead performance in the mid-septal position.

Methods And Results: A total of 299 ICD recipients (79% male, aged 65.2 ± 12.1 years, 83% primary prevention of sudden cardiac death) were randomized to receive the RV ICD electrode either in a mid-septal (n=145) or apical (n=154) location. Event-free survival was evaluated at 3 (primary endpoint) and 12 months (secondary endpoint). Events included a composite of lead revision, suboptimal right ventricular electrode performance (including defibrillation thresholds (DFT)>25 J) or lead position not in accordance with randomized location. Event-free survival at 3 (12) months was observed in 80.6% (72.3%) of patients randomized to a mid-septal and in 82.2% (72.1%) of patients randomized to an apical lead position, p=0.726 (p=0.969). Pre-defined margins for non-inferiority were not reached at 3 or 12 months. High DFT was found in 7 patients (5.0%) of the mid-septal and in 3 (2.2%) patients of the apical group (p=0.209).

Conclusion: In ICD recipients electrode positioning to the RV mid-septum or the RV apex results in slightly different rates concerning the survival free of lead revision, suboptimal right ventricular electrode performance or non-randomized lead position. Non-inferiority of the mid-septal lead location cannot be concluded. This should be taken into consideration when a mid-septal lead position is pursued.

Clinical Trial Registration: ClinicalTrials.gov identifier NCT00745745.
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http://dx.doi.org/10.1016/j.ijcard.2014.04.229DOI Listing
July 2014

Remote ICD-monitoring in detection and follow-up of triggers of idiopathic ventricular fibrillation: implications for the clinical management of IVF patients.

Int J Cardiol 2014 Jun 6;174(2):e29-31. Epub 2014 Apr 6.

Department of Cardiology and Angiology I, Heart Center, University of Freiburg, Freiburg, Germany. Electronic address:

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http://dx.doi.org/10.1016/j.ijcard.2014.03.207DOI Listing
June 2014

Vector selection of a quadripolar left ventricular pacing lead affects acute hemodynamic response to cardiac resynchronization therapy: a randomized cross-over trial.

PLoS One 2013 24;8(6):e67235. Epub 2013 Jun 24.

University Heart Center Freiburg, Germany.

Background: A suboptimal left ventricular (LV) pacing site may account for non-responsiveness of patients to cardiac resynchronization therapy (CRT). The vector selection of a novel quadripolar LV pacing lead, which was mainly developed to overcome technical issues with stimulation thresholds and phrenic nerve capture, may affect hemodynamic response, and was therefore assessed in this study. (German Clinical Trials Register DRKS00000573).

Methods And Results: Hemodynamic effects of a total of 145 LVPCs (9.1 per patient) of CRT devices with a quadripolar LV lead (Quartet™, St. Jude Medical) were assessed in 16/20 consecutive patients by invasive measurement of LV+dP/dtmax at an invasively optimized AV-interval in random order. Optimal (worst) LVPCs per patient were identified as those with maximal (minimal) %change in LV+dP/dtmax (%ΔLV+dP/dtmax) as compared to a preceding baseline. LV+dP/dtmax significantly increased in all 145 LVPCs (p<0.0001 compared to baseline) with significant intraindividual differences between LVPCs (p<0.0001). Overall, CRT acutely augmented %ΔLV+dP/dtmax by 31.3% (95% CI 24%-39%) in the optimal, by 21.3% (95% CI: 15%-27%) in the worst and by 28.2% (95% CI: 21%-36%) in a default distal LVPC. This resulted in an absolute additional acute increase in %ΔLV+dP/dtmax of 10.0% (95% CI: 7%-13%) of the optimal when compared to the worst (p<0.0001), and of 3.1% (95% CI: 1%-5%) of the optimal when compared to the default distal LVPC (p<0.001). Optimal LVPCs were not programmable with a standard bipolar lead in 44% (7/16) of patients.

Conclusion: The pacing configuration of a quadripolar LV lead determinates acute hemodynamic response. Pacing in the individually optimized configuration gives rise to an additional absolute 10% increase in %ΔLV+dP/dtmax when comparing optimal and worst vectors.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0067235PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3691154PMC
February 2014

Intracardiac Echocardiography during Catheter-Based Ablation of Atrial Fibrillation.

Cardiol Res Pract 2012 29;2012:921746. Epub 2012 May 29.

Department of Cardiology and Angiology, University Hospital of Freiburg, Hugstetter Stra β e 55, 79106 Freiburg, Germany.

Accurate delineation of the variable left atrial anatomy is of utmost importance during anatomically based ablation procedures for atrial fibrillation targeting the pulmonary veins and possibly other structures of the atria. Intracardiac echocardiography allows real-time visualisation of the left atrium and adjacent structures and thus facilitates precise guidance of catheter-based ablation of atrial fibrillation. In patients with abnormal anatomy of the atria and/or the interatrial septum, intracardiac ultrasound might be especially valuable to guide transseptal access. Software algorithms like CARTOSound (Biosense Webster, Diamond Bar, USA) offer the opportunity to reconstruct multiple two-dimensional ultrasound fans generated by intracardiac echocardiography to a three-dimensional object which can be merged to a computed tomography or magnetic resonance imaging reconstruction of the left atrium. Intracardiac ultrasound reduces dwell time of catheters in the left atrium, fluoroscopy, and procedural time and is invaluable concerning early identification of potential adverse events. The application of intracardiac echocardiography has the great capability to improve success rates of catheter-based ablation procedures.
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http://dx.doi.org/10.1155/2012/921746DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3368317PMC
August 2012

Dynamic ventricular overdrive stimulation in atrial fibrillation: effects on ventricular rate irregularity, ventricular pacing, and fusion beats.

Europace 2011 Dec 22;13(12):1688-94. Epub 2011 Jul 22.

Klinikum Coburg, II. Medizinische Klinik, Coburg, Germany.

Aims: In pacemaker patients with preserved atrio-ventricular (AV) conduction, atrial fibrillation (AF) can lead to symptomatic ventricular rate irregularity and loss of ventricular stimulation. We tested if dynamic ventricular overdrive (DVO) as a potentially pacemaker-integrated algorithm could improve both aspects.

Methods And Results: Different settings of DVO and ventricular-ventricular-inhibited-pacing (VVI) with different base rates were tested in two consecutive phases during electrophysiological studies for standard indications. Mean heart rate (HR), HR irregularity and percentage of ventricular pacing were evaluated. A fusion index (FI) indicative of the proportion of fusion beats was calculated for each stimulation protocol. Dynamic ventricular overdrive from the right ventricular apex was acutely applied in 38 patients (11 females, mean age 62.1 ± 11.5 years) with sustained AF and preserved AV conduction. Dynamic ventricular overdrive at LOW/MEDIUM setting increased the amount of ventricular pacing compared with VVI pacing at 60, 70, and 80 beats per minute (bpm; to 81/85% from 11, 25, and 47%, respectively; P < 0.05). It also resulted in a maximum decrease in interval differences (to 48 ± 18 ms from 149 ± 28, 117 ± 38, and 95 ± 46 ms, respectively; P < 0.05) and fusion (to 0.13 from 0.41, 0.42, and 0.36, respectively; P < 0.05) compared with VVI pacing at 60, 70, and 80 bpm. However, the application of DVO resulted in a significant increase in HR compared with intrinsic rhythm and VVI pacing at 80 bpm (to 97 bpm from 89 and 94 bpm, respectively; P < 0.05).

Conclusion: Dynamic ventricular overdrive decreases HR irregularity and increases ventricular pacing rate compared with VVI pacing at fixed elevated base rates and spontaneous rhythm. Fusion index might help to refine information on pacing percentages provided by device counters.
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http://dx.doi.org/10.1093/europace/eur243DOI Listing
December 2011

Early Heparin Administration Reduces Risk for Left Atrial Thrombus Formation during Atrial Fibrillation Ablation Procedures.

Cardiol Res Pract 2011 2;2011:615087. Epub 2011 Jul 2.

Department of Cardiology and Angiology, University Hospital Freiburg, Hugstetter Straße 55, 79106 Freiburg, Germany.

Objective. Despite the use of anticoagulation during left atrial (LA) ablation procedures, ischemic cerebrovascular accidents (CVAs) are recognized as a serious complication. Heparin is usually given after safe transseptal access has been obtained, resulting in a short unprotected dwell time of catheters within the LA, which may account for CVAs. We investigated the frequency of CVAs and LA thrombus formation as detected by intracardiac ultrasound (ICE) depending on the timing of heparin administration. Methods and Results. Sixty LA ablation procedures with the use of ICE were performed in 55 patients. Patients were grouped by heparin administration after (Group I, n = 13) and before (Group II, n = 47) transseptal access. Group I patients were younger (56.6 ± 13.7 versus 65.9 ± 9.9 years, P = .01); other clinical and echocardiographic characteristics did not differ between groups. Early thrombus formation was observed in 2 (15.4%) of group I patients as compared to 0% of group II patients (P = .04). One CVA (2.1%) occurred in one group II patient without prior thrombus detection, and none occurred in group I patients (P = ns). Conclusion. Early administration of heparin reduces the risk of early intracardiac thrombus formation during LA ablation procedures. This did not result in reduced rate of CVAs.
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http://dx.doi.org/10.4061/2011/615087DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3130977PMC
July 2011

Shock lead impedance alert: replace or reconsider?

Circ Arrhythm Electrophysiol 2011 Jun;4(3):e15-7

Department of Cardiology, University of Freiburg, Germany.

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http://dx.doi.org/10.1161/CIRCEP.110.961813DOI Listing
June 2011

Rationale and design of the SPICE study-septal positioning of ventricular ICD electrodes.

J Interv Card Electrophysiol 2011 Sep 31;31(3):247-54. Epub 2011 May 31.

Deutsches Herzzentrum und 1. Medizinische Klinik rechts der Isar, Faculty of Medicine, Technische Universität München, Munich, Germany.

Aim: Detrimental effects of right ventricular apical pacing have prompted the search for alternative pacing sites. Data from pacemaker studies suggest that the mid-septum may be a hemodynamically favorable pacing site within the right ventricle. However, data on the safety of implantable cardioverter defibrillator (ICD) lead placement in this location are limited. The aim of the SPICE study is to ascertain that implantation of a ventricular ICD lead at the mid-septum is not inferior to the traditional apical site in terms of feasibility and safety.

Methods: In total, 286 patients with the indication for ICD implantation will be included in the study and stratified in a 1:1 ratio to have the lead placed in the right ventricular apex or the mid-septum. Primary outcome measure of this randomized, prospective study is the event-free survival of lead-related complications at 3 months. The combined end point includes the feasibility to reach the randomized pacing site in combination with the achievement of adequate pacing, sensing, and defibrillation thresholds. Data analysis and sample size calculation are based on a non-inferiority design.

Conclusion: This trial will primarily assess the feasibility, safety, and efficacy of right ventricular ICD lead positioning in the mid-septum compared to the traditional apical position. Documentation of non-inferiority of the novel lead position in terms of applicability and safety will be the prerequisite for potential further trials that may evaluate long-term clinical effects associated with mid-septal lead positions.
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http://dx.doi.org/10.1007/s10840-011-9575-zDOI Listing
September 2011

Left atrial lesion formation and volume overload by open irrigation ablation technology during pulmonary vein antrum isolation: acute effects on cardiac hemodynamics.

J Interv Card Electrophysiol 2011 Aug 17;31(2):125-30. Epub 2011 Feb 17.

Herz- und Diabeteszentrum Nordrhein-Westfalen, Ruhr-Universität Bochum, Georgstr. 11, 32545, Bad Oeynhausen, Germany.

Purpose: Our goal was to evaluate acute effects of left atrial lesion formation and volume overload on hemodynamics during pulmonary vein antrum isolation (PVAI) as it might be a potential cause of acute pulmonary edema.

Methods: In consecutive patients presenting for PVAI, open irrigation ablation was performed (50 W, 48°C, 15 s lesion duration, saline flow rate 30 mL/min). Blood samples were drawn from the left atrium and the pulmonary artery immediately before and 30 min after PVAI. The cardiac output (CO) and stroke volume (SV) were calculated by the method of Fick.

Results: We included 61 (27 female, 61 ± 11 years) patients suffering from paroxysmal (px; 33) or persistent (per; 28) atrial fibrillation (AF) in this study. A total of 2,917 ± 242 mL of volume was infused (2,651 ± 223 mL pxAF vs. 3,184 ± 255 mL perAF, (p < 0.01)). Total ablation time was 60 ± 7 min (52 ± 7 min in pxAF vs. 69 ± 8 min in perAF; (p < 0.001)). CO increased from 5.2 ± 1.3 to 6.2 ± 1.5 L/min (p < 0.001) during PVAI (5.7 ± 1.3 to 6.5 ± 1.7 L/min in pxAF; (p < 0.002) and 4.8 ± 1.1 to 5.9 ± 1.2 L/min in perAF; (p < 0.001)). SV increased from 74 ± 24 to 83 ± 21 mL (p < 0.005) during PVAI, and subgroups showed an increase of 82 ± 23 to 88 ± 22 mL in pxAF (p < 0.009) and 62 ± 21 to 76 ± 16 mL in perAF (p < 0.009).

Conclusions: From our preliminary experience, left atrial scarring and volume overload during PVAI do not seem to impact negatively hemodynamics. On the contrary, an improvement in cardiac output was documented acutely independent of type of AF.
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http://dx.doi.org/10.1007/s10840-011-9545-5DOI Listing
August 2011

Intracardiac echocardiography for registration of rotational angiography-based left atrial reconstructions: a novel approach integrating two intraprocedural three-dimensional imaging techniques in atrial fibrillation ablation.

Europace 2011 Apr 28;13(4):492-8. Epub 2011 Jan 28.

Department of Cardiology, Heart and Diabetes Center North Rhine-Westfalia, Ruhr University Bochum, Georgstrasse 11, 32545 Bad Oeynhausen, Germany.

Aims: Image integration of three-dimensional (3D) reconstructions of left atrial (LA) and pulmonary vein (PV) anatomy into electroanatomical mapping (EAM) plays a major role in atrial fibrillation (AF) ablation. Point-by-point EAM is commonly used for registration of imported LA and PV anatomy. We aimed to assess the accuracy of intraprocedural rotational angiography-based LA imaging registered by spatial reconstruction of intracardiac echocardiography (ICE) in patients undergoing AF ablation.

Methods And Results: Twenty-two patients (11 males, 66 ± 12 years) were studied. Reconstructions of LA and PVs based on rotational angiography were registered by a second 3D reconstruction based on ICE. In a second step, EAM points were added to ICE 3D reconstructions. A 3D image of the LA and PVs was reconstructed in all patients by both imaging modalities. Rotational angiography and ICE-based LA 3D reconstructions took 11.5 ± 5.2 and 20.4 ± 11.2 min, respectively. A total of 17 ± 6 two-dimensional ICE fans were used for spatial reconstruction of ICE. The deviation between the two 3D shells was 2.6 ± 0.5 mm. Integration of 78 ± 58 EAM points into ICE 3D reconstruction did not significantly reduce the deviation to rotational angiography-based reconstructions (2.7 ± 0.6 mm). All PVs were isolated successfully.

Conclusions: Intraprocedural 3D reconstruction of LA and PVs for ablation of AF is feasible based on both rotational angiography and ICE. LA reconstructions based on rotational angiography can accurately be registered using 3D ICE shells. Additional EAM does not enhance accuracy. Therefore, registration of rotational angiography-based 3D reconstructions by 3D reconstructions from ICE seems to be an alternative technique to support AF ablation.
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http://dx.doi.org/10.1093/europace/eur003DOI Listing
April 2011

Nicorandil normalizes prolonged repolarisation in the first transgenic rabbit model with Long-QT syndrome 1 both in vitro and in vivo.

Eur J Pharmacol 2011 Jan 17;650(1):309-16. Epub 2010 Oct 17.

Department of Cardiology and Angiology, University Hospital of Freiburg, Freiburg, Germany.

Transgenic rabbits expressing loss-of-function pore mutants of the human gene KCNQ1 (K(v)LQT1-Y315S) have a Long QT-Syndrome 1 (LQT1) phenotype. We evaluated for the first time the effect of nicorandil, an opener of ATP-sensitive potassium channels, and of isoproterenol on cardiac action potential duration and heart rate dependent dispersion of repolarisation in transgenic LQT1 rabbits. In vivo LQT1 and littermate control were subjected to transvenous electrophysiological studies; in vitro monophasic action potentials were recorded from explanted Langendorff-perfused hearts. In vivo ventricular effective refractory periods (VERP) at the right ventricular base were significantly prolonged in LQT1 as compared to littermate control, resulting in a more pronounced VERP dispersion in LQT1. This difference in VERP dispersion between LQT1 and littermate control disappeared after infusion of nicorandil. In vitro, mean action potential durations (APD(75) and APD(90)) of LQT1 were significantly prolonged compared to littermate control at baseline. Nicorandil decreased APD(75) and APD(90) in LQT1 and littermate control at all stimulated heart rates. After adding nicorandil, the APD(90) at all hearts rates and the APD(75) at high heart rates were no longer different. Dispersion of repolarisation (∆APD(75) and ∆APD(90)) was heart rate dependently decreased after nicorandil at all tested stimulation cycle lengths only in LQT1. We demonstrated phenotypic differences of LQT1 and littermate control in vivo and in vitro. Nicorandil 20μmol/l improved repolarisation abnormalities and heterogeneities in transgenic LQT1 rabbits.
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http://dx.doi.org/10.1016/j.ejphar.2010.10.016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2997896PMC
January 2011

Incidental finding of a pulmonary embolus by intracardiac echocardiography during an atrial fibrillation ablation procedure.

Europace 2010 Aug 13;12(8):1199-200. Epub 2010 May 13.

Medizinische Klinik III, Kardiologie und Angiologie, Universitätsklinikum Freiburg, Hugstetter Str 55, 79106 Freiburg, Germany.

A 71-year-old female patient was referred for catheter ablation of drug-refractory, symptomatic atrial fibrillation. Initial intracardiac echocardiography (ICE) incidentally showed a mobile embolus stuck at a bifurcation of the right pulmonary artery. The procedure was suspended and the finding was subsequently confirmed by computed tomography pulmonary angiography. This case illustrates a potential value of real-time imaging by ICE during invasive procedures.
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http://dx.doi.org/10.1093/europace/euq121DOI Listing
August 2010

Image-integration of intraprocedural rotational angiography-based 3D reconstructions of left atrium and pulmonary veins into electroanatomical mapping: accuracy of a novel modality in atrial fibrillation ablation.

J Cardiovasc Electrophysiol 2010 Mar 5;21(3):278-83. Epub 2009 Oct 5.

Medizinische Klinik II, Klinikum Coburg, Coburg, Germany.

Introduction: Exact visualization of complex left atrial (LA) anatomy is crucial for safety and success rates when performing catheter ablation of atrial fibrillation (AF). The aim of our study was to validate the accuracy of integrating rotational angiography-based 3-dimensional (3D) reconstructions of LA and pulmonary vein (PV) anatomy into an electroanatomical mapping (EAM) system.

Methods And Results: In 38 patients (62 +/- 8 years, 25 females) undergoing catheter ablation of paroxysmal (n = 19) or persistent (n = 19) AF, intraprocedural rotational angiography of LA and PVs was performed. The subsequent 3D reconstruction and segmentation of LA and PVs was transferred to the EAM system and registered to the EAM. The distances of all EAM points to corresponding points on the LA syngo DynaCT Cardiac surface were calculated. Segmentation of LA with clear visualization of adjacent structures was possible in all patients. Also, the integrated segmentation of the LA was used to guide the encirclement of ipsilateral veins, which resulted in PV isolation in all patients. Integration into the 3D mapping system was achieved with a distance error of 2.2 +/- 0.4 mm when compared with the EAM surface. Subgroups with paroxysmal and persistent AF showed distance errors of 2.3 +/- 0.3 mm and 2.1 +/- 0.4 mm, respectively (P = n.s.).

Conclusion: Intraprocedural registration of LA and PV anatomy by contrast enhanced rotational angiography was feasible and accurate. There were no differences between patients with paroxysmal or persistent AF. Therefore, integration of rotational angiography-based reconstructions into 3D EAM systems might be helpful to guide catheter ablation for AF.
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http://dx.doi.org/10.1111/j.1540-8167.2009.01615.xDOI Listing
March 2010

Persistent left superior vena cava: an unusual but conquerable obstacle in device implantation.

Clin Res Cardiol 2009 Apr 13;98(4):268-70. Epub 2009 Feb 13.

Medizinische Universitätsklinik Innere Medizin III, Abt. für Kardiologie und Angiologie, Freiburg im Breisgau, Germany.

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http://dx.doi.org/10.1007/s00392-009-0755-0DOI Listing
April 2009

Three-dimensional left atrial and esophagus reconstruction using cardiac C-arm computed tomography with image integration into fluoroscopic views for ablation of atrial fibrillation: accuracy of a novel modality in comparison with multislice computed tomography.

Heart Rhythm 2008 Dec 12;5(12):1651-7. Epub 2008 Sep 12.

Medizinische Klinik, Klinikum Coburg, Coburg, Germany.

Background: Visualization of the left atrium (LA) and pulmonary veins (PVs) is crucial in PV isolation (PVI). Additional delineation of the esophagus might avoid severe side effects. Cardiac C-arm computed tomography (DynaCT Cardiac, Siemens AG, Forchheim, Germany) has been introduced as a novel intraprocedural imaging modality based on a rotational angiography.

Objectives: The purpose of this study was to prove the quantitative accuracy of DynaCT Cardiac as compared with multislice CT (MSCT) in imaging of the LA and PV in patients undergoing PVI.

Methods: Thirty-four consecutive patients (22 male, age 64 +/- 12 years) with symptomatic atrial fibrillation (AF) and indication for PVI were studied. Diameters of the PV, the LA appendage (LAA), and the descending aorta were measured, and the position of the esophagus was defined using preprocedural MSCT and intraprocedural DynaCT Cardiac.

Results: There was a significant correlation between both measurements for diameters of the LAA (r = 0.86, P <.05), PV (r = 0.98, P <.05), and the descending aorta (r = 0.98, P <.05). The overall correlation of vessel diameters was r = 0.99. The LA volumes correlation was r = 0.86 and P <.05. A significant difference of the esophageal position was found between preprocedural MSCT and intraprocedural DynaCT Cardiac (r = 0.53, P <.05).

Conclusions: DynaCT Cardiac is a novel intraprocedural rotational angiographic technique. It is highly accurate in displaying crucial structures for PVI in comparison with the results of MSCT. Therefore, DynaCT Cardiac can be used as an alternative imaging technique to improve PVI accuracy.
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http://dx.doi.org/10.1016/j.hrthm.2008.09.011DOI Listing
December 2008

Mortality in patients with atrial fibrillation has significantly decreased during the last three decades: 35 years of follow-up in 1627 pacemaker patients.

Europace 2008 Apr 8;10(4):391-4. Epub 2008 Mar 8.

Medizinische Klinik III, Kardiologie und Angiologie, Universitätsklinik Freiburg, Hugstetter Str. 55, 79106 Freiburg, Germany.

Aim: The impact of atrial fibrillation (AF) on mortality is not fully understood. We therefore sought to investigate long-term effects of AF on mortality in patients with the need for pacemaker (PM) therapy.

Methods And Results: A total of 1627 PM recipients with AF at implantation were followed in a single-centre, longitudinal study for up to 35 years. Baseline factors affecting survival and long-term follow-up were analysed. A total of 7362 patient-years of follow-up (PM implanted between 1971 and 2000, followed until 31 December 31 2005) were analysed. Female PM recipients lived significantly longer than male (P = 0.025; mean survival 91.9 vs. 72.1 months) despite older age at time of inclusion. Mean survival times almost doubled for patients implanted in the last decade, with 139.8 months in the nineties vs. 66.8 months in the seventies and 75.7 months in the eighties (P < 0.001). Male gender, age at implantation, non-syncopal bradycardia, and decade of implantation influenced survival.

Conclusion: Life expectancy in AF patients after PM implantation has doubled within the last three decades, with a mean survival in the overall population of 7.6 years for women and 6.0 years for men. Survival is influenced by several simple baseline characteristics, which may help to identify patients with very long survival times.
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http://dx.doi.org/10.1093/europace/eun014DOI Listing
April 2008

Atrial fibrillation reduces the atrial impedance amplitude during cardiac cycle: a novel detection algorithm to improve recognition of atrial fibrillation in pacemaker patients.

Europace 2007 Sep 1;9(9):812-6. Epub 2007 Jun 1.

Universitätsklinikum Freiburg, Medizinische Klinik III, Department of Cardiology and Angiology, Hugstetter Str 55, D-79106, Freiburg, Germany.

Aims: In carriers of dual chamber pacemakers and implantable cardioverter-defibrillators (ICD), detection of atrial fibrillation (AF) is crucial for adequate mode switch function and to avoid inappropriate shock delivery. Detection algorithms rely on the atrial rate and on the relationship of atrial to ventricular intracardiac electrograms, but the relative portion of misclassified AF episodes remains high. Although myocardial impedance is a reliable indicator of contraction, little is known about atrial impedance as a marker of atrial arrhythmias. Methods During an electrophysiological study, we investigated the effect of induced AF on impedance at the right atrial free wall (RAFW) and right atrial appendage (RAA) in 20 patients. Using biphasic square-wave pulses (128 Hz, 200 microA/15 micros), impedance changes were recorded during sinus rhythm (SR-1), atrial pacing at 120 beats/min, AF induced by rapid atrial burst pacing, and after spontaneous AF termination (SR-2). Results At the RAA, peak-to-peak impedance amplitude during cardiac cycle (DeltaZ) dropped from 51.7 +/- 35.3 Omega (SR-1) or 49.6 +/- 30.6 Omega (pacing) to 24.6 +/- 22.0 Omega (AF, P< or =0.0005), and subsequently increased to 37.7 +/- 24.7 Omega (SR-2, P < or = 0.0004 v. AF). At the RAFW, DeltaZ changed from 16.2 +/- 15.5 Omega (SR-1) or 13.5 +/- 9.9 Omega (pacing) to 5.9 +/- 4.1 Omega (AF, P < or = 0.003), and to 11.4 +/- 10.7 Omega (SR-2, P < or = 0.015). Given a discrimination threshold of 65%, the sensitivity and the specificity of DeltaZ to detect AF were 79 +/- 18 and 89 +/- 14%, respectively (95% confidence interval).

Conclusion: AF causes DeltaZ drop in pacemaker and ICD recipients. This impedance based algorithm can be used as an alternative method of AF detection.
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http://dx.doi.org/10.1093/europace/eum106DOI Listing
September 2007