Heart failure decompensation and all-cause mortality in relation to percent biventricular pacing in patients with heart failure: is a goal of 100% biventricular pacing necessary?

OBJECTIVES: The goal of this analysis was to determine the appropriate biventricular pacing target in patients with heart failure (HF). BACKGROUND: Cardiac resynchronization therapy (CRT) decreases the risk of death and HF hospitalization. However, the appropriate amount of biventricular pacing is ill-defined. METHODS: Mortality and HF hospitalization data from patients undergoing CRT in 2 trials (CRT RENEWAL [Cardiac Resynchronization Therapy Registry Evaluating Patient Response with RENEWAL Family Devices] and REFLEx [ENDOTAK RELIANCE G Evaluation of Handling and Electrical Performance Study]; n = 1,812) were analyzed in a post-hoc fashion. Subjects were grouped based on percent biventricular pacing quartiles with the use of Kaplan-Meier survival analysis. RESULTS: Subjects were age 72 +/- 11 years; 72% were men and 67% had coronary artery disease. Subjects paced 93% to 100% (quartiles 2 to 4) had a 44% reduction in hazard of an event compared with subjects paced 0% to 92% (quartile 1; hazard ratio [HR]: 0.56, p < 0.00001). Subjects paced 98% to 99% (quartile 3) had similar outcomes as subjects paced 93% to 97% (quartile 2; HR: 0.97, p = 0.82). Subjects paced 100% (quartile 4) had similar outcomes as subjects paced 98% to 99% (HR: 0.78, p = 0.17). There was a significant interaction between a history of atrial arrhythmia and percent pacing. Subjects with a history of atrial arrhythmia were more likely to be paced < or =92% (p < 0.001). CONCLUSIONS: For CRT patients in this retrospective analysis, the greatest magnitude of benefit was observed with >92% biventricular pacing.

Clinical and electrical performance of expanded polytetrafluoroethylene-covered defibrillator leads in comparison to traditional leads.

BACKGROUND: In the event of infection, erosion, or failure, fibrosis of a defibrillation lead can make extraction difficult. In the ENDOTAK RELIANCE G defibrillation lead, coils are covered with expanded polytetrafluoroethylene (ePTFE) to prevent tissue ingrowth. OBJECTIVE: The objective of the REFLEx Study was to evaluate if RELIANCE G defibrillation leads with ePTFE-covered coils are as good as comparative defibrillation leads with respect to electrical performance and termination of spontaneous tachyarrhythmias. METHODS: Patients were randomized to type of defibrillation lead--Guidant RELIANCE G lead or a non-ePTFE-covered lead of choice. Electrical performance success was defined as meeting all minimum standards in the respective manufacturer's manual for amplitude, threshold, and impedance. A noninferiority margin of 5% was prespecified. RESULTS: Electrical performance success at 12 months was 93.0% (280/301) for RELIANCE G and 94.5% (291/308) for comparative leads. The performance success rate for RELIANCE G did not differ significantly from study comparative (P = 0.04, noninferiority). For spontaneous episodes, first shock conversion success rate was 90% for RELIANCE G and 95% for study comparative (P = 0.89, noninferiority). Implant conversion testing was successful in 96.7% (524/542) of RELIANCE G patients and 94.3% (512/543) of comparative patients (chi-square P-value = 0.0784). About 55% (609/1115) of patients completed follow-up through month 12. CONCLUSION: Data from the REFLEx study indicate that ePTFE-covered leads are not inferior to comparative leads with respect to electrical performance and implant conversion testing. We cannot conclude that the first shock conversion efficacy of ePTFE covered leads was statistically noninferior to comparative leads.