Randomized controlled study of detection enhancements versus rate-only detection to prevent inappropriate therapy in a dual-chamber implantable cardioverter-defibrillator
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OBJECTIVES: The purpose of this study was to compare rate-only detection to enhanced detection in a dual-chamber implantable cardioverter-defibrillator (ICD), to discriminate ventricular tachycardia from supraventricular tachycardia. BACKGROUND: ICDs are highly effective in treating ventricular tachycardia (VT) or ventricular fibrillation (VF). However, they frequently deliver inappropriate therapy during supraventricular tachycardia (SVT). METHODS: We conducted a randomized clinical trial of detection enhancements in a dual-chamber ICD compared to control (rate-only) detection to discriminate VT from SVT. Detection enhancements included a specific standardized protocol identical for all patients for programming rate stability, sudden onset, atrial-to-ventricular relationship (sudden onset = 9% and rate stability = 10 ms; V > A "on"), and "sustained rate duration" (3 minutes). The primary endpoint was the time to first inappropriate therapy classified by a blinded events committee. RESULTS: One hundred forty-nine patients had a history of sustained VT or VF. Mean age (+/- SD) was 60 +/- 13 years; 83% were male, and mean ejection fraction was 35 +/- 15%. Control (n = 70) and "enhanced" (n = 79) groups did not differ with regard to age, sex, ejection fraction, or primary arrhythmia. The proportion of patients free of inappropriate therapy over time was significantly higher in the enhanced versus the control group (hazard ratio = 0.47, P = .011). High-energy shocks were reduced from 0.58 +/- 4.23 shocks/patient/month in the control group to 0.04 +/- 0.15 shocks/patient/month in the enhanced group (P = .0425). No patient programmed per protocol failed to receive therapy for VT detected by the ICD (422 VT episodes). CONCLUSIONS: Standardized programming in a dual-chamber ICD leads to a significant and clinically important reduction in inappropriate therapies compared to rate-only detection and does not compromise safety with respect to appropriate treatment of VT.
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