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Background: Atrial fibrillation (AF) is often detected during hospitalisation for surgery or medical illness and is often assumed to be due to the acute condition., Methods: The Asymptomatic Atrial Fibrillation and Stroke Evaluation in Pacemaker Patients and the Atrial Fibrillation Reduction Atrial Pacing Trial (ASSERT) study enrolled patients ≥ 65 years old without AF. Pacemakers or implantable cardioverter-defibrillators recorded device-detected AF. We identified participants who were hospitalised and compared the prevalence of AF before and after hospitalisation., Results: Among 2580 participants, 436 (16.9%) had a surgical or medical hospitalisation. In the 30 days following a first hospitalisation, 43 participants (9.9%, 95% confidence interval [CI] 7.2%-13.1%) had > 6 minutes of device-detected AF; 20 (4.6%, 95% CI 2.8%-7.0%) had > 6 hours. More participants had AF > 6 minutes in the 30 days following hospitalisation compared with the period 30-60 days before hospitalisation (9.9% vs 4.4%; P < 0.001). Similar results were observed for episodes > 6 hours (4.6% vs 2.3%, P = 0.03). Roughly half of participants with device-detected AF in the 30 days following hospitalisation had at least 1 episode of the same duration in the 6 months before (50% [95% CI 31.3%-68.7%] for > 6 min; 68.8% [95% CI 41.3%-89.0%] for > 6 h). Those with AF in the 30 days following hospitalisation were more likely to have had AF in the past (adjusted odds ratio [OR] 7.2, 95% CI 3.2-15.8 for > 6 min; adjusted OR 32.6, 95% CI 10.3-103.4 for > 6 h)., Conclusions: The prevalence of device-detected AF increases around the time of hospitalisation for noncardiac surgery or medical illness. About half of patients with AF around the time of hospitalisation previously had similar episodes., (Copyright © 2020 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.)

Introduction: Dual-coil leads (DC-leads) were the standard of choice since the first nonthoracotomy implantable cardioverter/defibrillator (ICD). We used contemporary data to determine if DC-leads offer any advantage over single-coil leads (SC-leads), in terms of defibrillation efficacy, safety, clinical outcome, and complication rates., Methods and Results: In the Shockless IMPLant Evaluation study, 2500 patients received a first implanted ICD and were randomized to implantation with or without defibrillation testing. Two thousand and four hundred seventy-five patients received SC-coil or DC-coil leads (SC-leads in 1025/2475 patients; 41.4%). In patients who underwent defibrillation testing (n = 1204), patients with both lead types were equally likely to achieve an adequate defibrillation safety margin (88.8% vs 91.2%; P = 0.16). There was no overall effect of lead type on the primary study endpoint of "failed appropriate shock or arrhythmic death" (adjusted HR 1.18; 95% CI, 0.86-1.62; P = 0.300), and on all-cause mortality (SC-leads: 5.34%/year; DC-leads: 5.48%/year; adjusted HR 1.16; 95% CI, 0.94-1.43; P = 0.168). However, among patients without prior heart failure (HF), and SC-leads had a significantly higher risk of failed appropriate shock or arrhythmic death (adjusted HR 7.02; 95% CI, 2.41-20.5). There were no differences in complication rates., Conclusion: In this nonrandomized evaluation, there was no overall difference in defibrillation efficacy, safety, outcome, and complication rates between SC-leads and DC-leads. However, DC-leads were associated with a reduction in the composite of failed appropriate shock or arrhythmic death in the subgroup of non-HF patients. Considering riskier future lead extraction with DC-leads, SC-leads appears to be preferable in the majority of patients., (© 2019 Wiley Periodicals, Inc.)

Objectives: The number of cardiac implantable electronic devices is growing worldwide because they play a relevant role in improving the survival rate in patients with specific heart diseases. Cardiac implantable electronic devices complications including infection, dysfunction or venous stenosis increase the need for the least traumatic way to explant leads. Our goal was to report the successes and procedural complication rates of transvenous lead extraction (TLE) in a consecutive series of patients., Methods: From 2010 to 2016, 108 patients underwent TLE of 227 leads due to endocarditis (n = 21; 19%), pocket infection (n = 58; 54%) or lead dysfunction (n = 29; 27%). In 98% (n = 106) of the patients, laser-assisted lead extraction was performed. In 2% (n = 2) of the patients, the application of a solitary locking stylet was sufficient. The patient mean age was 68 ± 14 years; 25% of the patients had previous cardiac surgery. TLE was performed a mean of 9 ± 6 years after the implantation of the existing device., Results: Complete procedural success (removal of all lead material from the vascular space) was achieved in 98.7% (n = 224), and clinical success (achievement of all clinical goals associated with the indication for lead removal and absence of major complications) was achieved in 98% (n = 106). In 2 patients the procedure failed due to a vascular tear requiring a thoracotomy. In 1 patient, complete lead extraction was not possible due to heavy calcification (coronary-sinus lead). The 30-day mortality rate was 3.7% (n = 4); the patients died of multiorgan failure (n = 1), cardiac failure (n = 1) and septicaemia (n = 2). The procedure-related major complication rate was 2% (n = 2)., Conclusions: Laser-assisted TLE seems to be a safe and effective procedure with an acceptable complication rate., (© The Author(s) 2018. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)

Aims: Cephalic vein cutdown (CVC) and subclavian puncture (SP) are widely used techniques for lead insertion of cardiac implantable electronic devices (CIEDs). Whether one technique is superior to the other, is still being debated. The purpose of this study was to compare CVC vs. SP for lead implantation in CIEDs with respect to the incidence of pneumothorax, lead failure, and bleeding., Methods and Results: We performed a systematic search of the pertinent literature on lead implantation in CIEDs via PubMed and Cochrane databases published over the last 25 years. Standard meta-analytic methods were applied to compare incidences of outcomes of interest. Sensitivity analysis was conducted to determine the impact of each study on the overall effect size. Risk of publication bias was assessed. A total of 20 studies were included in the analysis. These studies comprised more than 30 000 patients with more than 50 000 leads implanted via CVC or SP. The incidence of pneumothorax was lower with the CVC technique (n = 29/15 065, 0.19% vs. n = 205/15 824, 1.30%) [odds ratio (OR) 0.21, 95% confidence interval (CI) 0.10-0.42, P < 0.001]. With respect to overall lead failure, CVC was associated with better outcomes as compared to SP (n = 10/2002, 0.50% vs. n = 40/2080, 1.92%) (OR 0.25, 95% CI 0.13-0.51, P < 0.001). There was no significant difference in bleeding events (n = 25/811, 3.08% vs. n = 20/2136, 0.94%) (OR 1.69, 95% CI 0.37-7.79, P = 0.50)., Conclusion: This comprehensive meta-analysis demonstrates lower risk for pneumothorax and lead failure associated with CVC as compared to SP. Cephalic vein cutdown should constitute the preferred venous access.

Background: The Shockless IMPLant Evaluation (SIMPLE) trial showed that defibrillation testing (DT) at the time of implantable cardioverter-defibrillator (ICD) implant did not improve shock efficacy or reduce mortality. There are no data regarding the risk of complications, including stroke, among patients with atrial fibrillation (AF) who undergo DT., Objective: The purpose of this prospectively planned substudy of SIMPLE was to evaluate the effect of DT vs no DT on clinical outcomes among patients with AF., Methods: We compared efficacy (failed appropriate shock/arrhythmic death) and safety between patients who had AF on their immediate preprocedural ECG to the rest of the study patients. Then among patients with AF we compared these outcomes between patients randomized to DT vs no DT., Results: Of the 2500 patients enrolled in SIMPLE, 251 (10%) were in AF immediately before ICD implant. AF patients had an increased risk of failed appropriate shock/arrhythmic death (adjusted hazard ratio [HR] 1.64; 95% confidence interval [CI] 1.13-2.39; P = .009) and higher all-cause mortality (adjusted HR 1.58; 95% CI 1.2-2.08; P = .001). Among AF patients, perioperative complications and stroke did not significantly differ between DT vs no-DT groups (9.2% vs 5.4%; P = .2; and 1.7% vs 1.5%; P >.999, respectively). Failed appropriate shock or arrhythmic death occurred in 35 of 251 AF patients (14%), and the no-DT group proved not inferior to the DT group (HR 0.58; 95% CI 0.30-1.15; P noninferiority = .006)., Conclusion: ICD recipients with AF are at increased risk for adverse outcomes; however, DT does not improve arrhythmic survival or shock efficacy. There is no evidence that DT increased the occurrence of perioperative stroke., (Copyright © 2018 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Data on preferred ICD lead type and optimal RV lead position in patients undergoing CRT-D implantation are limited., Objectives: To compare dual- versus single-coil ICD leads and non-apical versus apical RV lead position and their impact on clinical parameters and survival in CRT-D recipients., Methods: A total of 563 consecutive patients with advanced heart failure and indication for CRT-D implantation were enrolled in two European tertiary centers. Endpoints were improvement in NYHA functional class, changes in echo- and electrocardiographic parameters, and all-cause and cardiovascular mortality., Results: In this retrospective analysis, a total of 313 (56%) dual- and 250 (44%) single-coil ICD leads were used. RV leads were placed non-apically in 262 (47%) and apically in 296 (53%) patients, respectively. Over a mean follow-up of 41 ± 34 months, all-cause mortality and cardiovascular mortality were similar for patients with dual- versus single-coil ICD lead (adjusted HR 0.81, 95% CI 0.58-1.12 and aHR 1.22, 95% CI 0.73-2.04) and non-apical versus apical RV lead position (aHR 0.98, 95% CI 0.71-1.36 and aHR 0.76, 95% CI 0.44-1.31). Non-apical RV lead position was associated with greater reduction in QRS duration after CRT implantation (- 14.4 ± 32.1 vs. - 4.3 ± 34.3 ms, p < 0.001)., Conclusions: We found no association between ICD lead type or RV lead position and outcomes in CRT-D recipients. Non-apical RV lead position was associated with larger reduction in QRS duration.

Background: Patients with hypertrophic cardiomyopathy (HCM) are considered to be at high risk for elevated defibrillation thresholds, periprocedural complications, and failed appropriate shocks., Objective: The purpose of this study was to determine the value of defibrillation testing (DT) in HCM patients undergoing implantable cardioverter-defibrillator (ICD) insertion., Methods: Defibrillation thresholds, perioperative complications, and long-term outcomes were compared between patients with HCM and those with ischemic cardiomyopathy (ICM) or dilated cardiomyopathy (DCM) enrolled in the SIMPLE (Shockless IMPLant Evaluation) trial (Clinialtrials.gov Identifier: NCT00800384). In patients with HCM, outcomes were also compared between those randomized to DT vs no DT., Results: Adequate defibrillation safety margin without system change was achieved in 46 of 52 (88.5%) HCM and 948 of 1047 (90.5%) ICM/DCM patients (P = .63). Perioperative complications occurred in 1 of 52 (1.9%) HCM patients with DT compared to 67 of 1047 (6.4%) ICM/DCM patients with DT (P = .37) or 3 of 42 (7.1%) HCM patients without DT (P = .32). During follow-up, there was no significant difference between HCM vs ICM/DCM patients in terms of all-cause mortality (adjusted hazard ratio [HR] 1.02, 95% confidence interval [CI] 0.45-2.34), composite of arrhythmic death or failed appropriate shock (adjusted HR 0.33, 95% CI 0.04-2.42), inappropriate shocks (adjusted HR 1.64, 95% CI 0.69-3.89), or system complications (adjusted HR 1.93, 95% CI 0.88-4.27). All-cause mortality (HR 0.26, 95% CI 0.03-2.20), appropriate (HR 0.24, 95% CI 0.03-2.05), and inappropriate shocks (HR 2.13, 95% CI 0.51-8.94) were similar in HCM patients without or those with DT., Conclusion: We did not find any difference in intraoperative defibrillation efficacy, perioperative complications, and long-term outcomes between patients with HCM and those with ICM/DCM. DT did not improve intraoperative or clinical shock efficacy in HCM patients., (Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Aims: Cardiac implantable electronic device (CIED) surgery is commonly performed in patients with atrial fibrillation (AF). The current analysis was undertaken to compare peri-operative anticoagulation management, bleeding, and thrombotic events in AF patients treated with dabigatran vs. warfarin., Methods and Results: This study included 611 patients treated with dabigatran vs. warfarin who underwent CIED surgery during the RE-LY trial. Among 201 warfarin-treated patients, warfarin was interrupted a median of 144 (inter-quartile range, IQR: 120-216) h, and 37 (18.4%) patients underwent heparin bridging. In dabigatran-treated patients (216 on 110 mg bid and 194 on 150 mg bid), the duration of dabigatran interruption was a median of 96 (IQR: 61-158) h. Pocket hematomas occurred in 9 (2.20%) patients on dabigatran and 8 (3.98%) patients on warfarin (P = 0.218). The occurrence of pocket hematomas was lower with dabigatran compared with warfarin with heparin bridging (RD: -8.62%, 95% CI: -24.15 to - 0.51%, P = 0.034) but not when compared with warfarin with no bridging (P = 0.880). Ischemic stroke occurred in 2 (0.3%) patients; one in the warfarin group (without bridging) and one in the dabigatran 150 mg bid group (P = 0.735)., Conclusion: In patients treated with dabigatran undergoing CIED surgery, interruption of dabigatran is associated with similar or lower incidence of pocket hematoma, when compared with warfarin interruption without or with heparin bridging, respectively. Whether uninterrupted dabigatran can reduce pocket hematoma or ischemic stroke remains to be evaluated., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.)

A patient with ischaemic cardiomyopathy received a secondary prevention VVI implantable cardioverter-defibrillator (ICD) after an episode of sustained ventricular tachycardia (VT). Because of recurrent VTs transmitted via CareLink, medical therapy was optimized and VT ablation was performed. Subsequently, a fast VT with a typical short-long-short initiation developed. In addition, there was an increasing need for ventricular pacing due to sinus bradycardia. This new type of VT could be successfully dealt with by upgrading to DDD ICD and activating the Ventricular Rate Stabilization algorithm.

Aims: Pocket haematoma is a common complication after defibrillator [implantable cardioverter defibrillator (ICD)] implantation, which is not only painful, but also increases the risk of device-related infection, and possibly embolic events. The present study seeks to evaluate the rate and predictors of clinically significant pocket haematoma., Methods and Results: This study included 2500 patients receiving an ICD in the SIMPLE trial. A clinically significant pocket haematoma was defined as a haematoma that required re-operation or interruption of oral anticoagulation (OAC) therapy. Clinically significant pocket haematoma occurred in 56 of 2500 patients (2.2%) of which 6 (10.7%) developed device-related infection. Patients who developed pocket haematoma were older (mean age 67.6 ± 8.8 years vs. 62.7 ± 11.6 years, P < 0.001), were more likely to have permanent atrial fibrillation (30.4 vs. 6.7%, P < 0.001) and a history of stroke (17.9 vs. 6.7%, P = 0.004), or were more likely to receive peri-operative OAC (50.0 vs. 28.4%, P < 0.001), unfractionated heparin (16.1 vs. 5.2%, P = 0.003), or low-molecular-weight heparin (37.5 vs. 17.5%, P < 0.001). Independent predictors of wound haematoma on multivariable analysis included the use of heparin bridging (OR 2.65, 95% CI 1.48-4.73, P = 0.001), sub-pectoral location of ICD (OR 2.00, 95% CI 1.12-3.57, P =0.020), previous stroke (OR 2.47, 95% CI 1.20-5.10, P = 0.015), an upgrade from permanent pacemaker (OR 2.52, 95% CI 1.07-5.94, P = 0.035), and older age (OR 1.03, 95% CI 1.00-1.06, P = 0.049)., Conclusion: Pocket haematoma remains an important complication of ICD implantation and is associated with a high risk of infection. Independent predictors of pocket haematoma include heparin bridging, prior stroke, sub-pectoral placement of ICD, older age, and upgrade from a pacemaker., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.)

Background: ASSERT demonstrated that subclinical atrial fibrillation (SCAF) is common in pacemaker patients without prior AF and is associated with increased risk of ischemic stroke or systemic embolism. SCAF episodes vary in duration and little is known about the incidence of different durations of SCAF, or their prognosis., Methods and Results: ASSERT followed 2580 patients receiving a pacemaker or ICD, aged >65 years with hypertension, without prior AF. The effect of SCAF duration on subsequent risk of ischemic stroke or embolism was evaluated with time-dependent covariate Cox models. Patients in whom the longest SCAF was ≤6 min were excluded from the analysis (n=125). Among 2455 patients during mean follow-up of 2.5 years, the longest single episode of SCAF lasted >6 min to 6 h in 462 patients (18.8%), >6-24 h in 169 (6.9%), and >24 h in 262 (10.7%). SCAF duration >24 h was associated with a significant increased risk of subsequent stroke or systemic embolism (adjusted hazard ratio [HR] 3.24, 95% confidence interval [CI] 1.51-6.95, P=0.003). The risk of ischemic stroke or systemic embolism in patients with SCAF between 6 min and 24 h was not significantly different from patients without SCAF., Conclusions: SCAF >24 h is associated with an increased risk of ischemic stroke or systemic embolism., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.)

Background: The implantable cardioverter-defibrillator (ICD) is the standard therapy to prevent sudden cardiac death in patients with coronary artery disease and unstable ventricular tachyarrhythmias. The prospective multinational SMS (Substrate Modification Study) was designed to assess whether prophylactic ablation of the arrhythmogenic substrate reduces or prevents the recurrence of ventricular tachycardia/ventricular fibrillation in such patients., Methods and Results: Of 111 patients included in an intention-to-treat analysis, 54 were randomly assigned catheter ablation plus ICD implantation (ablation group: 68±8 years; 47 men), whereas 57 were assigned ICD implantation without catheter ablation (ICD-only group: 66±8 years; 46 men). Primary study end point was the time to first recurrence of ventricular tachycardia/ventricular fibrillation. ICD episodes were assessed and verified by an independent board. Patients were followed up for 2.3±1.1 years. The primary end point was reached by 25 ablation patients and 26 ICD-only patients. Two-year event-free survival was estimated at 49.0% (95% confidence interval, 33.3%-62.9%) in the former and 52.4% (36.7%-65.9%) in the latter groups. Comparison of episode incidence revealed no significant difference in the primary end point ( P =0.84). In an Andersen-Gill regression model with multiple end point recurrences, the difference between the study arms significantly favored catheter ablation for both the primary end point and all but one of the predefined subgroups of detected arrhythmia events., Conclusions: SMS failed to meet the primary end point of time to first ventricular tachycardia/ventricular fibrillation recurrence. However, catheter ablation did reduce the total number of ICD interventions during the duration of follow-up., Clinical Trial Registration: https://clinicaltrials.gov. Unique identifier: NCT00170287., (© 2017 American Heart Association, Inc.)

Persistent left superior vena cava is known to be a challenging anatomic abnormality for transvenous cardiac device implantation. In the a case of a young man presenting with dilative cardiomyopathy with severely impaired left ventricular ejection fraction (LVEF) and second-degree atrioventricular block (AV block), cardiac resynchronization therapy (CRT) with defibrillator (CRT-D) implantation was indicated. A transvenous approach was attempted, but placement of the right ventricular lead was not successful due to anatomic abnormalities. Therefore, epicardial CRT leads were implanted via a left mini-thoracotomy. For primary prevention of sudden death, the patient was also fitted with an additional subcutaneous implantable cardioverter defibrillator (S-ICD). Any cross-talk between the devices was ruled out both intraoperatively and by ergometry prior to discharge. The combination of epicardial CRT-P with S‑ICD implantation might be a safe and effective alternative in patients with cardiac anatomic abnormalities.

Aims: The effects of digitalis on mortality in patients with structural heart disease are controversially discussed. We aimed to assess the effects of digitalis administration in implantable cardioverter defibrillator (ICD) recipients., Methods and Results: This retrospective analysis comprises 1020 consecutive patients who received an ICD at our institution and who were followed for up to 10 years (median 37 months). A total of 438 patients were receiving digitalis at the time of ICD implantation and 582 did not. Patients on digitalis were more often in atrial fibrillation and had more often a prolonged QRS duration of ≥120 ms, a severely impaired left ventricular ejection fraction, and higher New York Heart Association (NYHA) classification heart failure. Crude Kaplan-Meier analysis demonstrated significantly higher mortality in patients on digitalis (HR = 2.47; 95% CI 1.87-3.25; P = 0.001). After adjustment for patient characteristics found statistically significant in adjusted Cox regression analysis (age, gender, NYHA classification, and QRS duration of ≥120 ms), a HR of 1.65 remained (95% CI 1.14-2.39; P = 0.01). Patients on digitalis died more often from cardiac arrhythmic and cardiac non-arrhythmic causes than patients not on digitalis (P = 0.04). There was no difference in mortality between patients receiving digitoxin and those receiving digoxin (HR = 1.55; 95% CI 0.74-3.25; P = 0.25)., Conclusion: In this large ICD patient population, digitalis use at baseline was independently associated with increased mortality even after careful adjustment for possible confounders. Digitalis should be used with great caution in this population., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.)

Background: The Shockless IMPLant Evaluation trial randomized 2500 patients receiving a first implantable cardioverter-defibrillator (ICD)/cardiac resynchronization therapy-defibrillator device to have either defibrillation testing (DT) or no DT. It demonstrated that DT did not improve shock efficacy or reduce mortality., Objective: This prospective substudy evaluated the effect of DT on postoperative troponin levels and their predictive value for total and arrhythmic mortality., Methods: Troponin levels were measured between 6 and 24 hours after ICD implantation in 2200 of 2500 patients., Results: A postoperative serum troponin level above the upper limit of normal (ULN) was more common in patients undergoing DT (n = 509 [46.4%]) than in those not subjected to DT (n = 456 [41.3%]; P = .02). After excluding patients with known preoperative troponin levels above the ULN, consistent findings were observed (42.1% vs 37.5%; P = .04). During a mean follow-up of 3.1 ± 1.0 years, the annual mortality rate was increased in patients with postoperative troponin levels above the ULN (adjusted hazard ratio [HR] 1.43; 95% confidence interval [CI] 1.15-1.76; P = .001) irrespective of DT or no DT. Likewise, patients with elevated troponin levels had a significantly higher risk of arrhythmic death (adjusted HR 1.80; 95% CI 1.23-2.63; P = .002). The rate of first appropriate ICD shock (adjusted HR 0.89; 95% CI 0.71-1.12; P = .32) or failed appropriate shock (adjusted HR 1.02; 95% CI 0.59-1.76; P = .95) was similar in patients with or without troponin elevation., Conclusion: DT at the time of ICD implantation is associated with increased troponin levels, indicating subclinical myocardial injury caused by the procedure. Elevated troponin levels but not DT seem to predict clinical outcomes in ICD recipients., (Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Defibrillation testing by induction and termination of ventricular fibrillation is widely done at the time of implantation of implantable cardioverter defibrillators (ICDs). We aimed to compare the efficacy and safety of ICD implantation without defibrillation testing versus the standard of ICD implantation with defibrillation testing., Methods: In this single-blind, randomised, multicentre, non-inferiority trial (Shockless IMPLant Evaluation [SIMPLE]), we recruited patients aged older than 18 years receiving their first ICD for standard indications at 85 hospitals in 18 countries worldwide. Exclusion criteria included pregnancy, awaiting transplantation, particpation in another randomised trial, unavailability for follow-up, or if it was expected that the ICD would have to be implanted on the right-hand side of the chest. Patients undergoing initial implantation of a Boston Scientific ICD were randomly assigned (1:1) using a computer-generated sequence to have either defibrillation testing (testing group) or not (no-testing group). We used random block sizes to conceal treatment allocation from the patients, and randomisation was stratified by clinical centre. Our primary efficacy analysis tested the intention-to-treat population for non-inferiority of no-testing versus testing by use of a composite outcome of arrhythmic death or failed appropriate shock (ie, a shock that did not terminate a spontaneous episode of ventricular tachycardia or fibrillation). The non-inferiority margin was a hazard ratio (HR) of 1·5 calculated from a proportional hazards model with no-testing versus testing as the only covariate; if the upper bound of the 95% CI was less than 1·5, we concluded that ICD insertion without testing was non-inferior to ICD with testing. We examined safety with two, 30 day, adverse event outcome clusters. The trial is registered with ClinicalTrials.gov, number NCT00800384., Findings: Between Jan 13, 2009, and April 4, 2011, of 2500 eligible patients, 1253 were randomly assigned to defibrillation testing and 1247 to no-testing, and followed up for a mean of 3·1 years (SD 1·0). The primary outcome of arrhythmic death or failed appropriate shock occurred in fewer patients (90 [7% per year]) in the no-testing group than patients who did receive it (104 [8% per year]; HR 0·86, 95% CI 0·65-1·14; pnon-inferiority <0·0001). The first safety composite outcome occurred in 69 (5·6%) of 1236 patients with no-testing and in 81 (6·5%) of 1242 patients with defibrillation testing, p=0·33. The second, pre-specified safety composite outcome, which included only events most likely to be directly caused by testing, occurred in 3·2% of patients with no-testing and in 4·5% with defibrillation testing, p=0·08. Heart failure needing intravenous treatment with inotropes or diuretics was the most common adverse event (in 20 [2%] of 1236 patients in the no-testing group vs 28 [2%] of 1242 patients in the testing group, p=0·25)., Interpretation: Routine defibrillation testing at the time of ICD implantation is generally well tolerated, but does not improve shock efficacy or reduce arrhythmic death., Funding: Boston Scientific and the Heart and Stroke Foundation (Ontario Provincial office)., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Introduction: Atrial fibrillation (AF) is suggested to be less common among black and Asian individuals, which could reflect bias in symptom reporting and access to care. In the Asymptomatic AF and Stroke Evaluation in Pacemaker Patients and the AF Reduction Atrial Pacing Trial (ASSERT), patients with hypertension but no history of AF had AF recorded via an implanted pacemaker or defibrillator, thus allowing both symptomatic and asymptomatic AF incidence to be determined without ascertainment bias., Methods and Results: The ASSERT enrolled 2,580 patients in 23 countries in North America, Europe, and Asia. AF was defined as device-recorded AF episodes >190/min, lasting either for >6 minutes or >6 hours in duration. All ethnic groups with >50 patients were enrolled. Ethnic groups studied include Europeans (n = 1900), black Africans (n = 73), Chinese (n = 89), and Japanese (n = 105) patients. Compared to Europeans, black Africans had more risk factors for AF such as heart failure (27.8 vs 14.6%) and diabetes (41.7 vs 26.3%). At 2.5 years follow-up, all 3 non-European races had a lower incidence of AF (8.3%, 10.1%, and 9.5% vs 18.0%, respectively, for AF>6 minutes, P < 0.006). When adjusted for baseline difference, Chinese had a lower incidence of AF > 6 minutes (P < 0.007), and Japanese and black Africans had a lower incidence of AF > 6 hours (P < 0.04 and P = 0.057, respectively)., Conclusions: Black Africans, Chinese, and Japanese had lower incidence of AF compared to Europeans. In the case of black Africans, this is despite an increased prevalence of AF risk factors., (© 2013 Wiley Periodicals, Inc.)

Background: Pacing algorithms to prevent atrial fibrillation (AF) have been tested in studies of modest size and duration with inconclusive results., Objectives: To prospectively evaluate the relationship between subclinical AF and stroke in patients 65 years of age or older with no previous AF receiving a first pacemaker or an implantable cardioverter-defibrillator for standard indications. Three months following device implantation, pacemaker patients were randomized to have continuous atrial overdrive pacing (CAOP) algorithm turned "ON" or "OFF." The primary study outcome was development of electrocardiogram-documented AF >6 minutes., Results: A total of 2343 patients were randomized and followed for a mean of 2.5 years. The primary outcome occurred in 60 patients in the CAOP ON group (1.96% per year) and in 45 in the CAOP OFF group (1.44% per year; relative risk 1.38; 95% confidence interval 0.94-2.03; P = .10). Major clinical events (stroke, myocardial infarct, cardiovascular death, systemic embolism, heart failure hospitalization) occurred at similar frequencies in the 2 groups. In the CAOP ON group, 133 of the 1164 patients (11.4%) crossed over to CAOP OFF compared with 12 of the 1179 (1.0%) who crossed over from OFF to ON (P <.0001). False-positive device detections of AF were more common among patients assigned to CAOP ON (23%) than among patients assigned to CAOP OFF (7.7%; relative risk 2.99; 95% confidence interval 2.40-3.74; P <.001). Pacemaker generator replacement for battery depletion occurred in 4.4% of the subjects randomized to CAOP ON and in 2.5% of the patients assigned to CAOP OFF (relative risk 1.70; 95% confidence interval 1.08-2.67; P = .02)., Conclusions: CAOP does not prevent new-onset AF, is poorly tolerated, and accelerates pulse generator battery depletion., (Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Defibrillation testing (DT) has been an integral part of defibrillator (implantable cardioverter defibrillator [ICD]) implantation; however, there is little evidence that it improves outcomes. Surveys show a trend toward ICD implantation without DT, which now exceeds 30% to 60% in some regions. Because there is no evidence to support dramatic shift in practice, a randomized trial is urgently needed. The SIMPLE trial will determine if ICD implantation without any DT is noninferior to implantation with DT. Patients will be eligible if they are receiving their first ICD using a Boston Scientific device (Boston Scientific, Natick, MA). Patients will be randomized to DT or no DT at the time of ICD implantation. In the DT arm, physicians will make all reasonable efforts to ensure 1 successful intraoperative defibrillation at 17 J or 2 at 21 J. The first clinical shock in all tachycardia zones will be set to 31 J for all patients. The primary outcome of SIMPLE will be the composite of ineffective appropriate shock or arrhythmic death. The safety outcome of SIMPLE will include a composite of potentially DT-related procedural complications within 30 days of ICD implantation. Several secondary outcomes will be evaluated, including all-cause mortality and heart failure hospitalization. Enrollment of 2,500 patients with 3.5-year mean follow-up will provide sufficient statistical power to demonstrate noninferiority. The study is being performed at approximately 90 centers in Canada, Europe, Israel, and Asia Pacific with final results expected in 2013., (Copyright © 2012 Mosby, Inc. All rights reserved.)

Background: Pacemakers can automatically identify and catalog atrial high-rate episodes (AHREs). While most AHREs represent true atrial tachyarrhythmia/atrial fibrillation (AT/AF), a review of stored electrograms suggests that a substantial proportion do not. As AHREs may lead to the initiation of oral anticoagulation, it is crucial to understand the relationship between AHREs and true AT/AF., Objective: To compare the positive predictive value of AHREs for electrogram-confirmed AT/AF for various atrial rates and episode durations., Methods: By using data from 2580 patients who participated in the ASymptomatic atrial fibrillation and Stroke Evaluation in pacemaker patients and the AF Reduction atrial pacing Trial, all AHREs >6 minutes and >190 beats/min with available electrograms were reviewed to determine whether they represented true AT/AF. The positive predictive value of these AHREs was assessed for episode durations of 6 minutes, 30 minutes, 6 hours, and 24 hours at atrial rates of 190 and 250 beats/min., Results: Of 5769 AHREs >6 minutes and >190 beats/min, 82.7% were true AT/AF and 17.3% were false positives (predominantly due to repetitive non-re-entrant ventriculoatrial synchrony). False positives dropped to 6.8%, 3.3%, and 1.8% when the threshold duration was increased to 30 minutes, 6 hours, and 24 hours, respectively. Increasing the threshold heart rate to 250 beats/min added little to the positive predictive value when longer threshold durations were used., Conclusions: By using a cutoff of >6 minutes and >190 beats/min, the rate of false-positive AHREs is 17.3%, making physician review of electrograms essential. For AHREs lasting >6 hours, the rate of false positives is 3.3%, making physician review less crucial., (Copyright © 2012 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: One quarter of strokes are of unknown cause, and subclinical atrial fibrillation may be a common etiologic factor. Pacemakers can detect subclinical episodes of rapid atrial rate, which correlate with electrocardiographically documented atrial fibrillation. We evaluated whether subclinical episodes of rapid atrial rate detected by implanted devices were associated with an increased risk of ischemic stroke in patients who did not have other evidence of atrial fibrillation., Methods: We enrolled 2580 patients, 65 years of age or older, with hypertension and no history of atrial fibrillation, in whom a pacemaker or defibrillator had recently been implanted. We monitored the patients for 3 months to detect subclinical atrial tachyarrhythmias (episodes of atrial rate >190 beats per minute for more than 6 minutes) and followed them for a mean of 2.5 years for the primary outcome of ischemic stroke or systemic embolism. Patients with pacemakers were randomly assigned to receive or not to receive continuous atrial overdrive pacing., Results: By 3 months, subclinical atrial tachyarrhythmias detected by implanted devices had occurred in 261 patients (10.1%). Subclinical atrial tachyarrhythmias were associated with an increased risk of clinical atrial fibrillation (hazard ratio, 5.56; 95% confidence interval [CI], 3.78 to 8.17; P<0.001) and of ischemic stroke or systemic embolism (hazard ratio, 2.49; 95% CI, 1.28 to 4.85; P=0.007). Of 51 patients who had a primary outcome event, 11 had had subclinical atrial tachyarrhythmias detected by 3 months, and none had had clinical atrial fibrillation by 3 months. The population attributable risk of stroke or systemic embolism associated with subclinical atrial tachyarrhythmias was 13%. Subclinical atrial tachyarrhythmias remained predictive of the primary outcome after adjustment for predictors of stroke (hazard ratio, 2.50; 95% CI, 1.28 to 4.89; P=0.008). Continuous atrial overdrive pacing did not prevent atrial fibrillation., Conclusions: Subclinical atrial tachyarrhythmias, without clinical atrial fibrillation, occurred frequently in patients with pacemakers and were associated with a significantly increased risk of ischemic stroke or systemic embolism. (Funded by St. Jude Medical; ASSERT ClinicalTrials.gov number, NCT00256152.).

Background: Celivarone is a new antiarrhythmic agent developed for the treatment of ventricular arrhythmias. This study investigated the efficacy and safety of celivarone in preventing implantable cardioverter-defibrillator (ICD) interventions or death., Methods and Results: Celivarone (50, 100, or 300 mg/d) was assessed compared with placebo in this randomized, double-blind, placebo-controlled, parallel-group study. Amiodarone (200 mg/d after loading dose of 600 mg/d for 10 days) was used as a calibrator. A total of 486 patients with a left ventricular ejection fraction ≤40% and at least 1 ICD intervention for ventricular tachycardia or ventricular fibrillation in the previous month or ICD implantation in the previous month for documented ventricular tachycardia/ventricular fibrillation were randomized. Median treatment duration was 9 months. The primary efficacy end point was occurrence of ventricular tachycardia/ventricular fibrillation-triggered ICD interventions (shocks or antitachycardia pacing) or sudden death. The proportion of patients experiencing an appropriate ICD intervention or sudden death was 61.5% in the placebo group; 67.0%, 58.8%, and 54.9% in the celivarone 50-, 100-, and 300-mg groups, respectively; and 45.3% in the amiodarone group. Hazard ratios versus placebo for the primary end point ranged from 0.860 for celivarone 300 mg to 1.199 for celivarone 50 mg. None of the comparisons versus placebo were statistically significant. Celivarone had an acceptable safety profile., Conclusions: Celivarone was not effective for the prevention of ICD interventions or sudden death., Clinical Trial Registration: http://www.clinicaltrials.gov. Unique identifier: NCT00993382.

Background: Long-term lead failure is a known complication of ICD therapy. The precise incidence and sequelae of insulation defects at the tricuspid level, however, are not well characterized., Objective: This study determined the risk of lead failure, with particular emphasis on insulation defects at the level of the tricuspid valve, in a large series of consecutive ICD recipients., Methods: Data from 357 consecutive patients, who had received transvenous 7 and 8 French ICD-leads (St. Jude Medical, Riata family) and were followed at our center, formed the basis of this study., Results: During a mean follow-up of 42 ± 24 months, 30 of 357 (8%) patients required surgical intervention due to lead failure. For overall lead defects, lead access via the subclavian vein and subpectoral device placement were independent predictors of overall lead failure (OR 3.47, 95% CI 1.38-8.72, P = 0.013 and OR 3.83, 95% CI 1.77-8.27, P = 0.001, respectively). Lead insulation defects at the level of the tricuspid valve accounted for 20% of all lead failures. Diagnosis of this specific insulation defect could only be established by fluoroscopy, while electrical parameters were within normal limits in all of these patients. On univariate but not on multivariate analysis the presence of nonischemic cardiomyopathy was a predictor of this lead complication (OR 8.2, CI 1.5-46.1, P = 0.02)., Conclusion: Insulation defects of 7 and 8 French ICD leads at the tricuspid level represent an important complication of device therapy. Even moderate changes in lead impedance within the normal limits at follow-up should prompt careful fluoroscopic evaluation to avoid spurious shocks., (© 2011 Wiley Periodicals, Inc.)

Aims: There are continued debates on potential proarrhythmic effects of intracoronary bone marrow-derived progenitor cell (BMC) therapy for treatment of chronic heart failure. Implantable cardioverter-defibrillators (ICDs), a mainstay of heart failure therapy, provide the possibility of validly assessing arrhythmias in patients with chronic heart failure. The aim of this analysis was to assess the arrhythmogenic potential of intracoronary BMC therapy, continuously documented by ICD-stored intracardiac electrograms., Methods and Results: Matched cohort study of 112 patients receiving intracoronary administration of autologous BMC and 224 heart failure patients, matched for age, gender, and left ventricular ejection fraction fitted with an ICD. Within a follow-up period of 2 years (total patient-years at risk: 595 years), no significant difference was detected for ICD-stored episodes of ventricular tachycardia (VT; 25.0 vs. 27.1%; P = 0.779), VT/ventricular fibrillation treated by antitachycardia pacing or ICD shock (15.6 vs. 15.5%; P = 0.956), or death from arrhythmic cause (4.2 vs. 1.0%; P = 0.667). Predictors of occurrence of major arrhythmic events were parameters of advanced heart failure and implantation of ICD for secondary prevention; no influence could be detected for BMC administration (odds ratio = 1.198; P = 0.440)., Conclusion: There is no evidence that intracoronary administration of BMC aggravates life-threatening arrhythmias in patients with chronic heart failure.

Background: although implantable cardioverter-defibrillators (ICDs) lower mortality in stable patients with low ejection fraction late after myocardial infarction, randomized trials of ICD versus control subjects implanted early after myocardial infarction do not show mortality benefit. Our objective was to investigate possible mechanisms underlying the lack of mortality benefit in the Defibrillation in Acute Myocardial Infarction Trial (DINAMIT)., Methods and Results: this is a secondary analysis of the prospective randomized clinical trial. Outpatients with recent (6 to 40 days) acute myocardial infarction, left ventricular dysfunction (ejection fraction <35%), and low heart rate variability were randomized to ICD (n=311) or to standard medical therapy (n=342). In a competing-risks analysis, those factors that increased the risk of arrhythmic death also increased the risk of nonarrhythmic deaths. After adjustment for these factors, receiving an ICD was associated with a decreased risk of arrhythmic death (hazard ratio, 0.33; 95% confidence interval, 0.15 to 0.71) but an increase in nonarrhythmic death (hazard ratio, 1.70; 95% confidence interval, 1.00 to 2.80). In an adjusted time-dependent analysis, patients receiving an ICD and having appropriate ICD therapy had a 15.1% yearly hazard of mortality compared with 5.2% in ICD patients with no appropriate therapy (P<0.001). The reduction in sudden death in ICD patients was completely offset by increased nonarrhythmic deaths, which were greatest in patients receiving ICD shock therapy (hazard ratio, 6.0; 95% confidence interval, 2.8 to 12.7)., Conclusions: in patients receiving ICDs early after myocardial infarction, those factors that are associated with arrhythmia requiring ICD therapy are also associated with a high risk of nonsudden death, negating the benefit of ICDs in this setting.

Background: Cardiac-resynchronization therapy (CRT) benefits patients with left ventricular systolic dysfunction and a wide QRS complex. Most of these patients are candidates for an implantable cardioverter-defibrillator (ICD). We evaluated whether adding CRT to an ICD and optimal medical therapy might reduce mortality and morbidity among such patients., Methods: We randomly assigned patients with New York Heart Association (NYHA) class II or III heart failure, a left ventricular ejection fraction of 30% or less, and an intrinsic QRS duration of 120 msec or more or a paced QRS duration of 200 msec or more to receive either an ICD alone or an ICD plus CRT. The primary outcome was death from any cause or hospitalization for heart failure., Results: We followed 1798 patients for a mean of 40 months. The primary outcome occurred in 297 of 894 patients (33.2%) in the ICD-CRT group and 364 of 904 patients (40.3%) in the ICD group (hazard ratio in the ICD-CRT group, 0.75; 95% confidence interval [CI], 0.64 to 0.87; P<0.001). In the ICD-CRT group, 186 patients died, as compared with 236 in the ICD group (hazard ratio, 0.75; 95% CI, 0.62 to 0.91; P = 0.003), and 174 patients were hospitalized for heart failure, as compared with 236 in the ICD group (hazard ratio, 0.68; 95% CI, 0.56 to 0.83; P<0.001). However, at 30 days after device implantation, adverse events had occurred in 124 patients in the ICD-CRT group, as compared with 58 in the ICD group (P<0.001)., Conclusions: Among patients with NYHA class II or III heart failure, a wide QRS complex, and left ventricular systolic dysfunction, the addition of CRT to an ICD reduced rates of death and hospitalization for heart failure. This improvement was accompanied by more adverse events. (Funded by the Canadian Institutes of Health Research and Medtronic of Canada; ClinicalTrials.gov number, NCT00251251.).

Background: A rapidly growing number of long-QT syndrome (LQTS) patients are being treated with an implantable cardioverter-defibrillator (ICD). ICDs may pose problems, especially in the young. We sought to determine the characteristics of the LQTS patients receiving an ICD, the indications, and the aftermath., Methods and Results: The study population included 233 patients. Beginning in 2002, data were collected prospectively. Female patients (77%) and LQT3 patients (22% of genotype positive) were overrepresented; mean QTc was 516±65 milliseconds; mean age at implantation was 30±17 years; and genotype was known in 59% of patients. Unexpectedly, 9% of patients were asymptomatic before implantation. Asymptomatic patients, almost absent among LQT1 and LQT2 patients, represented 45% of LQT3 patients. Patients with cardiac symptoms made up 91% of all study participants, but only 44% had cardiac arrest before ICD implantation. In addition, 41% of patients received an ICD without having first been on LQTS therapy. During follow-up, 4.6±3.2 years, at least 1 appropriate shock was received by 28% of patients, and adverse events occurred in 25%. Appropriate ICD therapies were predicted by age <20 years at implantation, a QTc >500 milliseconds, prior cardiac arrest, and cardiac events despite therapy; within 7 years, appropriate shocks occurred in no patients with none of these factors and in 70% of those with all factors., Conclusions: Reflecting previous concepts, ICDs were implanted in some LQTS patients whose high risk now appears questionable. Refined criteria for implantation, reassessment of pros and cons, ICD reprogramming, and consideration for other existing therapeutic options are necessary.

Aims: Evaluation of cause-specific mortality in a large cohort of unselected implantable cardioverter defibrillator (ICD) recipients., Methods and Results: Causes of death of consecutive ICD recipients implanted over a 10 year period were analysed. Overall 822 patients (age 63 +/- 11 years, 80% male, EF 34 +/- 14%, secondary prevention 65%) were followed for 43 +/- 30 months during which time 225 patients died (annual mortality 7.6%). Causes of death were cardiac arrhythmic in 16%, cardiac non-arrhythmic in 39%, non-cardiac vascular in 4%, non-cardiovascular in 27%, and unknown in 13%. Advanced age [relative risk (RR) 1.23 per decades, 95% confidence interval (CI) 1.06-1.43], NYHA class >II (RR 2.27, 95% CI 1.51-3.41), renal failure (RR 1.57, 95% CI 1.15-2.14), use of amiodarone (RR 2.56, 95% CI 1.91-3.43), digitalis (RR 1.87, 95% CI 1.40-2.49), diuretics (RR 1.89, 95% CI 1.35-2.66) were independent predictors of all-cause mortality. Predictors for arrhythmic mortality were NYHA class >II (RR 12, 95% CI 3.69-37.5), spontaneous or inducible VT as indication for ICD therapy (RR 2.53, 95% CI 1.06-6.05), and use of amiodarone (RR 3.95, 95% CI 2.02-7.75)., Conclusion: In this unselected group of ICD recipients, at least 16% of patients died from arrhythmic causes. Risk factors associated with arrhythmic mortality were a history of spontaneous or inducible VT, higher NYHA class, and amiodarone use.

Aims: Implantable cardioverter defibrillator (ICD) technology has become more complex, particularly with respect to biventricular resynchronization devices. The incidence of hardware-related complications in single (SC)-, dual (DC)-, and triple (BiV)-chamber devices requiring surgical revision has not been investigated systematically., Methods and Results: We analysed data from consecutive ICD recipients implanted between January 2000 and December 2007 with respect to the need of surgical re-intervention for device- or lead-related complications. Generator exchanges due to normal battery depletion were not considered. From 816 patients (81% male, 69% ischaemic cardiomyopathy, 48% secondary prevention ICDs) followed for 31 +/- 24 months (2118 cumulative patient-years), 98 patients underwent 110 revisions (5.2% per patient-year). Complications included lead-related revision procedures in 81 cases and generator-related problems in 29 cases. The annual incidence of surgical revision due to complications was 11.8% in BiV compared with 4.9% in SC and 4.1% in DC patients (P = 0.002). This higher revision rate was mainly caused by lead-related complications. Implantation of a BiV system was an independent risk factor of the need for surgical revision (relative risk 2.37, 95% confidence interval 1.38-4.04)., Conclusion: Even with long-lasting operator experience, complications requiring surgical revision remain a clinically important problem of ICD therapy. The incidence of complications is significantly higher in BiV resynchronization devices than in SC and DC systems.

Objectives: The goal of this study was to determine whether azimilide, as compared with placebo, will reduce the number of emergency department (ED) visits and hospitalizations caused by arrhythmias or cardiac events in patients with an implantable cardioverter-defibrillator (ICD)., Background: Patients with an ICD may require ED visits and hospitalizations because of arrhythmias, which trigger ICD therapies. The effect of adjunctive antiarrhythmic therapy on these outcomes is not known., Methods: A total of 633 patients with an ICD were randomized in the SHIELD (SHock Inhibition Evaluation with AzimiLiDe) trial, a blinded, placebo-controlled randomized trial of the investigational class III antiarrhythmic azimilide (75 and 125 mg/day), and, prospectively, cardiac and arrhythmic ED visits and hospitalization data were collected over 1 year., Results: All patients had symptomatic sustained ventricular tachycardia (72%) or ventricular fibrillation (28%) before study entry. Overall, 44% (n = 276) experienced at least 1 cardiac ED visit or hospitalization. Among 214 patients assigned to placebo, 38.3% had at least 1 arrhythmic-related ED visit or hospitalization compared with 21.8% of 220 patients assigned to 75-mg azimilide (p < 0.001) and 27.6% of 199 patients assigned to 125 mg azimilide (p < 0.05). Symptomatic ventricular tachycardia treated by antitachycardia pacing, shocks, and shocks plus symptomatic arrhythmias were significant predictors of cardiac-related ED visits or hospitalizations (relative risk: 2.0, 3.0, and 3.1, respectively). In a stepwise logistic regression model, the presence of congestive heart failure (New York Heart Association functional class II/III) was the only additional independent predictor of cardiac ED visits or hospitalizations., Conclusions: Azimilide significantly reduces the number of ED visits and hospitalizations in patients with an ICD at high risk of arrhythmias.

Aims: Cardiac resynchronization therapy (CRT) is indicated in patients with heart failure and bundle branch block. It is less clear whether this includes patients with pre-existing right ventricular pacemaker/defibrillator systems, particularly with respect to implantation success and clinical benefit., Methods and Results: In consecutive patients scheduled for CRT, we prospectively compared implantation success, procedural parameters, and clinical response in 'de novo' vs. upgrade procedures of previously implanted right ventricular systems. CRT implantation was attempted in 79 consecutive patients (64 +/- 11 years, 63 male, 38 ischaemic, 41 non-ischaemic cardiomyopathy). De novo implantation was performed in 61 patients, upgrade procedures in 18 patients. Implant success (92 vs. 94%, P = 1.00), procedure duration (153 +/- 43 vs. 164 +/- 65 min, P = 0.51), fluoroscopy time (25 +/- 18 vs. 32 +/- 22 min, P = 0.18) or dose (40 +/- 31 vs. 52 +/- 49 Gy/cm(2), P = 0.35), and response rate (66 vs. 59%, P = 0.5) were comparable for both groups., Conclusion: Procedural aspects, implantation success, and clinical response to CRT were comparable for patients undergoing de-novo vs. upgrade procedures. Accordingly, patient selection for upgrading should be the same as for new CRT implantation.

Aims: External cardioversion (ECV) of atrial fibrillation (AF) may damage implanted pacemaker and cardioverter-defibrillator (ICD) systems. This prospective study evaluated the safety and efficacy of ECV comparing mono- to biphasic shock waveforms in patients with implanted rhythm devices., Methods and Results: Patients with pacemaker or ICD systems and an indication for ECV were randomized to receive mono- or biphasic shocks. Systems were tested immediately before and after ECV, 1 h and 1 week later with respect to device and lead integrity. Forty-four patients (71 +/- 10 years, 31 male; 29 pacemakers, 12 ICDs, three cardiac resynchronization systems) underwent ECV with antero-posterior paddle orientation (monophasic in 21 and biphasic in 23 patients). Pacing impedances were reduced immediately after ECV (atrial 402-392 ohm, P < 0.001; ventricular 517-496 ohm, P = 0.001) and returned to baseline values within 1 week. Ventricular sensing was reduced immediately after ECV (12.4-11.6 mV, P = 0.004). There was no device or lead dysfunction in any patient. ECV was successful in 42/44 patients (95%), cumulative energy was significantly lower for biphasic compared with monophasic shocks (P = 0.001)., Conclusion: ECV for AF seems to be safe and effective in patients with implanted rhythm devices.

Aims: The purpose of this study was to assess the incidence, features, and clinical sequelae of 'electrical storm' (ES)., Methods and Results: This study is a prospectively designed secondary analysis of SHIELD; a randomized trial of azimilide for suppression of ventricular tachycardia/fibrillation (VT/VF) leading to implanted cardioverter defibrillator (ICD) therapies. Systematic and rigorous follow-up and blinded adjudication of ICD therapy allowed identification of all ESs (>/=3 separate VT/VF episodes leading to ICD therapies within 24 h). Of 633 ICD recipients, 148 (23%) experienced at least one ES over 1-year follow-up. No clinical predictors of ES were identified. Frequent VT episodes accounted for 91% of all ESs, with the remaining being VF alone or both VT plus VF. ES led to a 3.1-fold increase in arrhythmia-related hospitalization (95% CI 2.3-4.3; P<0.0001) compared with patients with isolated VT/VF, and to a 10.2-fold increase (95% CI 6.4-16.3; P<0.0001) compared with patients without VT/VF. Compared with placebo, azimilide (75 and 125 mg/day) reduced the risk of recurrent ES by 37% (HR=0.63, 95% CI 0.35-1.11, P=0.11) and 55% (HR=0.45, 95% CI 0.23-0.87, P=0.018), respectively. However, the reduction in time-to-first ES did not reach statistical significance by both doses (75 and 125 mg) of azimilide (HR=0.82, 95% CI 0.56-1.19, P=0.29 and HR=0.69, 95% CI 0.46-1.04, P=0.07), respectively., Conclusion: ES is common and unpredictable in ICD recipients and it is a strong predictor of hospitalization.

Background: Many patients with implanted cardioverter defibrillators (ICDs) receive adjunctive antiarrhythmic drug therapy, most commonly amiodarone or sotalol. The effects of these drugs on defibrillation energy requirements have not been previously assessed in a randomized controlled trial., Methods and Results: The Optimal Pharmacological Therapy in Cardioverter Defibrillator Patients (OPTIC) trial was a randomized clinical trial evaluating the efficacy of amiodarone plus beta-blocker and sotalol versus beta-blocker alone for reduction of ICD shocks. Within OPTIC, a prospectively designed substudy evaluated the effects of the 3 treatment arms on defibrillation energy requirements. Defibrillation thresholds (DFTs) were measured (binary step-down protocol) at baseline and again after 8 to 12 weeks of therapy in 94 patients, of whom 29 were randomized to receive beta-blocker therapy (control group), 35 to amiodarone plus beta-blocker, and 30 to sotalol. In the control group, the mean DFT decreased from 8.77+/-5.15 J at baseline to 7.13+/-3.43 J (P=0.027); in the amiodarone group, DFT increased from 8.53+/-4.29 to 9.82+/-5.84 J (P=0.091). In the sotalol group, DFT decreased from 8.09+/-4.81 to 7.20+/-5.30 J (P=0.21). DFT changes in the beta-blocker and the amiodarone group were significantly different (P=0.006). In all patients, adequate safety margins for defibrillation were maintained. No clinical variable predicted baseline DFT or changes in DFT on therapy., Conclusions: Although amiodarone increased DFT, the effect size with modern ICD systems is very small. Therefore, DFT reassessment after the institution of antiarrhythmic drug therapy with amiodarone or sotalol is not routinely required.

Context: Implantable cardioverter defibrillator (ICD) therapy is effective but is associated with high-voltage shocks that are painful., Objective: To determine whether amiodarone plus beta-blocker or sotalol are better than beta-blocker alone for prevention of ICD shocks., Design, Setting, and Patients: A randomized controlled trial with blinded adjudication of events of 412 patients from 39 outpatient ICD clinical centers located in Canada, Germany, United States, England, Sweden, and Austria, conducted from January 13, 2001, to September 28, 2004. Patients were eligible if they had received an ICD within 21 days for inducible or spontaneously occurring ventricular tachycardia or fibrillation., Intervention: Patients were randomized to treatment for 1 year with amiodarone plus beta-blocker, sotalol alone, or beta-blocker alone., Main Outcome Measure: Primary outcome was ICD shock for any reason., Results: Shocks occurred in 41 patients (38.5%) assigned to beta-blocker alone, 26 (24.3%) assigned to sotalol, and 12 (10.3%) assigned to amiodarone plus beta-blocker. A reduction in the risk of shock was observed with use of either amiodarone plus beta-blocker or sotalol vs beta-blocker alone (hazard ratio [HR], 0.44; 95% confidence interval [CI], 0.28-0.68; P<.001). Amiodarone plus beta-blocker significantly reduced the risk of shock compared with beta-blocker alone (HR, 0.27; 95% CI, 0.14-0.52; P<.001) and sotalol (HR, 0.43; 95% CI, 0.22-0.85; P = .02). There was a trend for sotalol to reduce shocks compared with beta-blocker alone (HR, 0.61; 95% CI, 0.37-1.01; P = .055). The rates of study drug discontinuation at 1 year were 18.2% for amiodarone, 23.5% for sotalol, and 5.3% for beta-blocker alone. Adverse pulmonary and thyroid events and symptomatic bradycardia were more common among patients randomized to amiodarone., Conclusions: Despite use of advanced ICD technology and treatment with a beta-blocker, shocks occur commonly in the first year after ICD implant. Amiodarone plus beta-blocker is effective for preventing these shocks and is more effective than sotalol but has an increased risk of drug-related adverse effects.Clinical Trials Registration ClinicalTrials.gov Identifier: NCT00257959.

Purpose of the Review: The aim of this article is to summarize the most relevant findings of recently published trials on prophylactic implantable cardioverter defibrillator therapy., Recent Findings: A number of important randomized clinical trials on the efficacy of prophylactic implantable cardioverter defibrillator therapy in patients deemed to be at high risk for ventricular tachyarrhythmias have recently reported their results. Patients with chronic ischemic cardiomyopathy, a long history of heart failure, and an ejection fraction of 0.30 or below benefit from preventive device therapy and are thus candidates for prophylactic defibrillator implantation. For this purpose, a single chamber device appears to be appropriate since there have been no prospective studies showing convincing clinical benefit by adding an atrial lead. Prophylactic implantable cardioverter defibrillator therapy should not be used in patients with recent myocardial infarction. There is convincing evidence from one trial that benefit from the defibrillator in coronary patients accrue after a considerable time has elapsed from the most recent infarct, presumably at least 6 months or perhaps longer. Finally, in patients with chronic dilated non-ischemic cardiomyopathy and a left ventricular ejection fraction of 0.35 or below, there is also benefit from prophylactic implantable cardioverter defibrillator therapy., Summary: Taken together, these trials allow an evidence-based approach to primary prevention of sudden cardiac death in patients with both ischemic and non-ischemic cardiomyopathy.

Introduction: Implantable cardioverter-defibrillator (ICD) therapy has been shown to improve survival in patients with structural heart disease and at high risk for life threatening ventricular arrhythmias. Whether elderly patients benefit from device therapy in a similar way as younger patients is largely unknown., Methods: We retrospectively analyzed data from 375 consecutive ICD recipients with structural heart disease. Patients were divided into two groups, younger than 70 years at time of ICD implantation (group 1) or 70 years or older (group 2). Main outcome measures were time to death from any cause and time from first appropriate ICD therapy to death., Results: Group 1 and 2 patients were comparable with respect to clinical presentation and average follow-up duration. In the elderly patient group, 78% received an ICD for secondary prevention versus 63% in group 1 (p = 0.007). During a mean follow-up period of 26.5 +/- 18.1 months, there was no significant difference in overall mortality among the two groups: 47 patients died, 34 (12.5%) of group 1 versus 13 (12.7%) of group 2. The average time to death was 28.4 +/- 16.7 vs 30.4 +/- 22.1 months after device implantation, respectively (p = ns). There was no difference in time from device implantation to first adequate ICD therapy and time from first appropriate ICD therapy to death among the two groups (p = ns). Device associated complications were comparable in both groups., Conclusions: Elderly ICD recipients had comparable survival rates and appropriate use of the ICD compared to younger individuals.

The Multicenter Automatic Defibrillator Implantation Trial II (MADIT II) and the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT) have established that patients with a reduced ejection fraction gain an overall mortality benefit from prophylactic implantable cardioverter-defibrillator therapy. Only a small proportion of the patients in these studies, however, have received life-saving therapy from the defibrillator. Because defibrillator therapy is invasive and expensive, patients with a low ejection fraction would benefit from effective risk stratification so that defibrillator therapy was used only in those at significant risk. In this review, we analyze prospective clinical trials that have evaluated microvolt T-wave alternans (MTWA) testing as a predictor of ventricular tachyarrhythmic events in populations of patients similar to those studied in MADIT II or SCD-HeFT; that is, patients with a reduced ejection fraction who were not selected on the basis of a history of ventricular tachyarrhythmias. In these studies, the average annual rate of fatal and nonfatal ventricular tachyarrhythmic events among the patients who tested negative for MTWA was around 1%. This rate is so low that it is unlikely that such patients would benefit from implantable cardioverter-defibrillator therapy. The mortality, moreover, was lower among MTWA-negative patients who did not receive implantable defibrillators than that observed in the MADIT II and SCD-HeFT patients who received implantable cardioverter-defibrillators. In response, patients with a low ejection fraction who are being considered for implantable cardioverter-defibrillator therapy should undergo MTWA testing as part of their evaluation.

25 years after the first coronary artery patient received an implantable cardioverter defibrillator (ICD), many randomized controlled trials on prophylactic ICD therapy have been conducted. Taken together, these trials allow an evidence-based approach to primary prevention of sudden cardiac death in patients after a myocardial infarction. Patients with chronic ischemic cardiomyopathy, a long history of heart failure, and an ejection fraction of < or = 0.30 benefit from preventive device therapy and are thus candidates for prophylactic defibrillator implantation. For this purpose, a single-chamber device appears to be appropriate, since there have been no prospective studies showing convincing clinical benefit by adding an atrial lead. For similar patients who have additional intraventricular conduction delays, a biventricular ICD must be considered. However, this decision must be based on individual considerations until more data from prospective trials become available. Prophylactic ICD therapy should not be used in patients with recent myocardial infarction. There is convincing evidence that ICD benefit in coronary patients accrues after a considerable time having elapsed from the most recent infarct, presumably at least 6 months or perhaps longer.

This report presents the rationale and study design details of the SHock Inhibition Evaluation with Azimilide study, which is recruiting 624 patients with implantable cardioverter-defibrillators (ICDs) who are at risk for life-threatening ventricular arrhythmia, randomized to azimilide 75 mg, azimilide 125 mg, or placebo and followed for 1 year. The objective of this study is to determine the effect of azimilide versus placebo on the symptomatic ventricular arrhythmia burden using a unique statistical analysis based on the unusual temporal distribution of symptomatic ICD therapies. The primary efficacy end points are time to all-cause shocks and time to all-cause shocks plus symptomatic ventricular arrhythmic events triggering antitachycardia pacing measured from randomization.

Background: Implantable cardioverter-defibrillator (ICD) therapy has been shown to improve survival in patients with various heart conditions who are at high risk for ventricular arrhythmias. Whether benefit occurs in patients early after myocardial infarction is unknown., Methods: We conducted the Defibrillator in Acute Myocardial Infarction Trial, a randomized, open-label comparison of ICD therapy (in 332 patients) and no ICD therapy (in 342 patients) 6 to 40 days after a myocardial infarction. We enrolled patients who had reduced left ventricular function (left ventricular ejection fraction, 0.35 or less) and impaired cardiac autonomic function (manifested as depressed heart-rate variability or an elevated average 24-hour heart rate on Holter monitoring). The primary outcome was mortality from any cause. Death from arrhythmia was a predefined secondary outcome., Results: During a mean (+/-SD) follow-up period of 30+/-13 months, there was no difference in overall mortality between the two treatment groups: of the 120 patients who died, 62 were in the ICD group and 58 in the control group (hazard ratio for death in the ICD group, 1.08; 95 percent confidence interval, 0.76 to 1.55; P=0.66). There were 12 deaths due to arrhythmia in the ICD group, as compared with 29 in the control group (hazard ratio in the ICD group, 0.42; 95 percent confidence interval, 0.22 to 0.83; P=0.009). In contrast, there were 50 deaths from nonarrhythmic causes in the ICD group and 29 in the control group (hazard ratio in the ICD group, 1.75; 95 percent confidence interval, 1.11 to 2.76; P=0.02)., Conclusions: Prophylactic ICD therapy does not reduce overall mortality in high-risk patients who have recently had a myocardial infarction. Although ICD therapy was associated with a reduction in the rate of death due to arrhythmia, that was offset by an increase in the rate of death from nonarrhythmic causes., (Copyright 2004 Massachusetts Medical Society.)

Background: The tachycardia detection interval (TDI) in implantable cardioverter/defibrillators (ICDs) is conventionally programmed according to the slowest documented ventricular tachycardia (VT), with a safety margin of 30 to 60 ms. With this margin, VTs above the TDI may occur. However, longer TDIs are associated with an increased risk of inappropriate therapy. We hypothesized that patients with slow VTs (<200 bpm) may benefit from a long TDI and a dual-chamber detection algorithm compared with a conventionally programmed single-chamber ICD., Methods and Results: Patients with VTs <200 bpm were implanted with a dual-chamber ICD that was randomly programmed to a dual-chamber algorithm and a TDI of > or =469 ms or to a single-chamber algorithm with a TDI 30 to 60 ms above the slowest documented VT cycle length and the enhancement criteria of cycle length variation and acceleration. The primary combined end point was the number of all inappropriate therapies, VTs above the TDI, and VTs with significant therapy delay (>2 minutes). After 6 months, a crossover analysis was performed. Total follow-up was 1 year. One hundred two patients were included in the study. The programmed TDI was 500+/-36 ms during the dual-chamber phase and 424+/-63 ms during the single-chamber phase. For the primary end point (inappropriate therapies, VTs above the TDI, or VTs with detection delay), a moderate superiority of the dual-chamber mode was found: Mann-Whitney estimator=0.6661; 95% CI, 0.5565 to 0.7758; P=0.0040., Conclusions: Dual-chamber detection with a longer TDI improves VT detection and does not increase the rate of inappropriate therapies despite a considerable increase in tachycardia burden.

The implantable defibrillator (ICD) effectively palliates arrhythmogenic events and thereby reduces total mortality in patients after a first episode of cardiac arrest. At present, four randomized controlled trials have addressed the issue of primary prevention by the ICD in patients with coronary artery disease and two small studies are available dealing with patients suffering from nonischemic cardiomyopathy. Importantly, none of the randomized studies in patients suffering from coronary artery disease has examined the potential role of the ICD in patients early after myocardial infarction. Within the next 12 months, important additional data is expected from several studies which have completed patient enrollment and follow-up. All studies are prospective randomized trials investigating the effects of ICD compared to optimal medical therapy. This paper summarizes the rationale, design and specific contributions of the Defibrillator in Myocardial infarction trial (DINAMIT) in comparison to other relevant studies on primary prevention of sudden cardiac death.