Biventricular pacing was superior to conventional right ventricular pacing in patients with atrioventricular block and left ventricular systolic dysfunction with NYHA class I, II, or III heart failure. (Funded by Medtronic; BLOCK HF ClinicalTrials.gov number, NCT00267098.).

for the REPLACE Registry InvestigatorsBackground-Prospective studies defining the risk associated with pacemaker or implantable cardioverter-defibrillator replacement surgeries do not exist. These procedures are generally considered low risk despite results from recent retrospective series reporting higher rates. Methods and Results-We prospectively assessed predefined procedure-related complication rates associated with elective pacemaker or implantable cardioverter-defibrillator generator replacements over 6 months of follow-up. Two groups were studied: those without (cohort 1) and those with (cohort 2) a planned transvenous lead addition for replacement or upgrade to a device capable of additional therapies. Complications were adjudicated by an independent events committee. Seventy-two US academic and private practice centers participated. Major complications occurred in 4.0% (95% confidence interval, 2.9 to 5.4) of 1031 cohort 1 patients and 15.3% (95% confidence interval, 12.7 to 18.1) of 713 cohort 2 patients. In both cohorts, major complications were higher with implantable cardioverter-defibrillator compared with pacemaker generator replacements. Complications were highest in patients who had an upgrade to or a revised cardiac resynchronization therapy device (18.7%; 95% confidence interval, 15.1 to 22.6). No periprocedural deaths occurred in either cohort, although 8 later procedure-related deaths occurred in cohort 2. The 6-month infection rates were 1.4% (95% confidence interval, 0.7 to 2.3) and 1.1% (95% confidence interval, 0.5 to 2.2) for cohorts 1 and 2, respectively. Conclusions-Pacemaker and implantable cardioverter-defibrillator generator replacements are associated with a notable complication risk, particularly those with lead additions. These data support careful decision making before device replacement, when managing device advisories, and when considering upgrades to more complex systems. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT00395447.

on behalf of the MADIT-CRT Executive CommitteeBackground-We hypothesized that combined assessment of factors that are associated with favorable reverse remodeling after cardiac resynchronization-defibrillator therapy (CRT-D) can be used to predict clinical response to the device. Methods and Results-The study population comprised 1761 patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy (MADIT-CRT). Best-subset regression analysis was performed to identify factors associated with echocardiographic response (defined as percent reduction in left ventricular end-diastolic volume 1 year after CRT-D implantation) and to create a response score. Cox proportional hazards regression analysis was used to evaluate the CRT-D versus defibrillator-only reduction in the risk of heart failure or death by the response score. Seven factors were identified as associated with echocardiographic response to CRT-D and made up the response score (female sex, nonischemic origin, left bundle-branch block, QRS Ն150 milliseconds, prior hospitalization for heart failure, left ventricular end-diastolic volume Ն125 mL/m 2 , and left atrial volume Ͻ40 mL/m 2 ). Multivariate analysis showed a 13% (PϽ0.001) increase in the clinical benefit of CRT-D per 1-point increment in the response score (range, 0 -14) and a significant direct correlation between risk reduction associated with CRT-D and response score quartiles: Patients in the first quartile did not derive a significant reduction in the risk of heart failure or death with CRT-D (hazard ratioϭ0.87; Pϭ0.52); patients in the second and third quartiles derived 33% (Pϭ0.04) and 36% (Pϭ0.03) risk reductions, respectively; and patients in the upper quartile experienced a 69% (PϽ0.001) risk reduction (P for trendϭ0.005). Conclusion-Combined assessment of factors associated with reverse remodeling can be used for improved selection of patients for cardiac resynchronization therapy. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT00180271.