Head-To-Head Comparison of Arrhythmia Discrimination Performance of Subcutaneous and Transvenous ICD Arrhythmia Detection Algorithms: The START Study

Arrhythmia Detection with S-ICD Versus Transvenous ICDs. 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 TVICD 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. (J Cardiovasc Electrophysiol, Vol. 23, pp. 359-366, April 2012)