Twenty-one patients (4.6%) had ventricular lead–related complications, including fracture or insulation defect, dislodgment, high ventricular threshold or loss of capture, and lead perforation.

Overall, 9 patients (2.0%) had hematoma, 9 patients (2.0%) had infections, and 6 patients (1.3%) had pneumothoraces. No significant difference was observed between groups (even disqualifying the atrial lead–related events Z-VAD-FMK concentration in the single-chamber setting group). The OPTION trial is the first prospective, randomized study evaluating inappropriate shock occurrence with dual-chamber settings and single-chamber settings during long-term follow-up in an ICD population. It shows a significant reduction of inappropriate shocks in the dual-chamber setting versus the single-chamber setting arm, with equivalent rates of cardiovascular events and death in both arms.

Conceptually, because of the information on atrial rhythm, dual-chamber ICDs are expected to discriminate more precisely between supraventricular and ventricular tachyarrhythmias compared with single-chamber ICD. Recent analyses of large-scale trials point toward learn more few inappropriate shocks with dual-chamber ICDs, which may be less than with conventional single-chamber ICDs 17 and 18. However, the presumed superiority of dual-chamber ICD has never been shown in prospective, randomized trials for inappropriate shocks on per patient analysis 19, 20, 21 and 22. The lack of statistical significance in these studies may be attributed to inadequate sample sizes of early studies, study design, devices and algorithms used, and device programming (single-zone vs. multiple-zone programming). The results of our trial add an important

piece of evidence for the reduction of inappropriate shocks with dual-chamber Elongation factor 2 kinase ICDs (2.6% vs. 7.6% at 1 year, p = 0.015; 4.3% vs. 10.3% at study end, p = 0.012). The yearly rate of inappropriate shocks in OPTION (2.6% in the dual-chamber setting group) was of the same magnitude as in the recently conducted MADIT-RIT (Multicenter Automated Defibrillation Trial–Reduction in Inappropriate Therapy) trial (31) and lower than in several earlier large-scale trials, in which rates of 11% to 13% were reported 12, 13, 14, 15, 16, 17, 18, 19 and 20. However, recent studies have reported very low overall rates of inappropriate shocks, which may be attributed to shorter follow-up periods, to specific device settings, including a higher tachycardia therapy cutoff rate, and to longer detection times 32, 33, 34 and 35. Moreover, it should be noted that the high crossover rate observed in our study from dual-chamber to single-chamber therapy may have even diluted the magnitude of the difference between the groups in this intention-to-treat analysis. The rate of appropriate shocks in this trial was not significantly different between the groups, at 11.7% and 12.