Single-coil Versus Dual-coil ICD Lead Shock Efficacy in a Large ICD Registry

Single-coil leads account for 5–10% of transvenous implantable cardioverterdefibrillator (ICD) leads. Single-coil leads improve extractability while allowing adequate safety margin for defibrillation in new generation devices (output of 35–41 joules). Limited clinical shock efficacy data exist in patients having single-coil ICD systems. A retrospective analysis was conducted from St. Jude Medical’s ACT ICD registry (St. Paul, MN). Treated arrhythmia episodes were independently adjudicated to confirm true VT/VF (ventricular tachycardia or ventricular fibrillation) events receiving an ICD shock for termination over 2 years of follow-up post implant. Only appropriate shocks delivered for VT/VF were used for comparisons in this study. A total of 5,424 patients (269 single coil, 5,155 dual coil) were enrolled. A total of 618 patients (22 single versus 606 dual) received a total of 1,447 ICD shocks in the registry (38 single versus 1409 dual). Of the 38 shocks delivered in patients with single-coil leads, 20 were delivered appropriately in 12 patients for VT/VF, 17/20 converted with a single shock (85%). Comparison was made with an ageand left ventricular ejection fraction (LVEF)-matched subset of 80 shock episodes from 55 dual-coil lead patients. Single shock conversion for VT/VF was 70/80 (87.3%) in the dual-coil group. No difference was seen in singleversus dual-coil first shock arrhythmia termination of VT/ VF (85% single-coil versus 87.5% dual-coil, p50.90). Single-coil ICD leads appear equivalent to dual-coil ICD leads in regards to clinical first shock efficacy to rescue VT/VF in modern highvoltage ICD systems followed for 2 years post device implant. Owing to the small single-coil lead sample size, a larger study is necessary to confirm the findings.