Does the S-ICD system improve arrhythmia discrimination specificity compared to transvenous ICD systems in patients undergoing ICD implantation?
The S-ICD system demonstrates excellent ventricular arrhythmia detection comparable to transvenous systems, but with significantly better specificity for discriminating supraventricular arrhythmias.
BACKGROUND: The development of a totally subcutaneous implantable defibrillator (S-ICD) system requires a new approach for arrhythmia detection. To evaluate arrhythmia discrimination of one such system, the Subcutaneous versus Transvenous Arrhythmia Recognition Testing (START) study was designed as a prospective, multicenter trial comparing simulated sensing performances of the S-ICD system with single- (SC-TV) and dual-chamber transvenous (DC-TV) implantable cardioverter-defibrillator (ICD) systems. METHODS: At ICD implantation, induced ventricular and atrial arrhythmias were recorded simultaneously in transvenous (right ventricular RV → superior vena cava SVC+ Coil) and cutaneous electrode configurations. Recorded signals of ventricular (n = 46) and atrial arrhythmias (n = 50) with ventricular rates >170 bpm from 64 patients were used to compare detection performance of the S-ICD system with TV-ICD systems from 3 manufacturers. Appropriate detection of ventricular tachyarrhythmias was assessed with devices programmed in single-zone (rate ≥ 170 bpm) and dual-zone configurations (ventricular fibrillation ≥ 240 bpm; ventricular tachycardia ≥ 170 bpm). S-ICD specificity performance for supraventricular arrhythmias was compared to single- and dual-chamber devices in a dual-zone configuration. RESULTS: Appropriate detection of ventricular tachyarrhythmias for subcutaneous and TV devices in single- and dual-zone configurations was 100% and >99%, respectively. Specificity for supraventricular arrhythmias was significantly better for the S-ICD system compared to 2 of 3 TV systems, as well as the composite of TV devices (98.0%S-ICD vs 76.7%SC-TV range: 64.0-92.0% vs 68.0%DC-TV range: 32.7-89.8%; P < 0.001). CONCLUSION: Appropriate ventricular arrhythmia detection is excellent for all ICD systems evaluated; however, specificity of supraventricular arrhythmia discrimination by the S-ICD system is better than discrimination by 2 of 3 TV systems.
Gold et al. (Fri,) studied this question.
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