ABSTRACT
Determination of the optimal interventricular (VV) delay in cardiac resynchronization therapy currently relies on costly, time-consuming echocardiographic (ECHO) methods. This study evaluated the performance of a new intracardiac electrogram (IEGM)-based VV method compared to the aortic velocity time integral (AVTI) method of VV delay optimization. The study included two patient groups. Eleven patients enrolled by a single center in the Rhythm II ICD trial underwent prospective comparisons of the AVTI at the VV interval determined by the IEGM VV method versus the maximum AVTI at the echocardiographically determined optimal VV delay. In 61 patients enrolled in the RHYTHM VV trial, the same testing methods were compared retrospectively. In the prospective study, the maximum AVTI by the ECHO-based method (24.3 +/- 7.9 cm), was closely correlated with maximum AVTI by the IEGM-based method (23.9 +/- 7.9 cm; concordance correlation coefficient = 0.99; 95% confidence, lower limit of 98%. Likewise, in the retrospective analysis, the ECHO-determined maximum AVTI (22.1 +/- 8.2 cm) was similar to that determined by the IEGM-based method (20.9 +/- 8.3 cm; concordance correlation coefficient = 0.98; 95% confidence, lower limit of 97%).
Subject(s)
Cardiac Pacing, Artificial , Electrocardiography/methods , Ventricular Function, Left , Aged , Aorta/physiopathology , Bundle-Branch Block/therapy , Echocardiography , Female , Heart Failure/therapy , Humans , Male , Pacemaker, Artificial , Prospective Studies , Retrospective Studies , Ventricular RemodelingABSTRACT
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.
