A prospective randomized trial of single- or dual-chamber implantable cardioverter-defibrillators to minimize inappropriate shock risk in primary sudden cardiac death prevention

Aims: Dual-chamber implantable cardioverter-defibrillators (ICDs) may improve specificity and reduce the risk of inappropriate shocks, and enhance atrial arrhythmia (AT/AF) detection to permit stroke prevention compared with single-chamber ICDs, but at additional expense and risk. Methods and results: Patients (n = 100) receiving primary prevention ICDs at two USA and two Israeli centres were randomized to dual-chamber or single-chamber devices between December 2008 and December 2010 and were followed for 1 year. Programming in both groups included: delayed detection to avoid therapy for non-sustained episodes; high detection cut-off rates to avoid treating slower, better tolerated arrhythmias; minimized right ventricular pacing; and routine use of supraventricular-ventricular tahcycardia discriminators and antitachycardia pacing. The primary outcome was the proportion of patients with inappropriate shocks. One patient in each group (2%) received inappropriate shocks (P = 1.00). Death occurred in two patients in the single-chamber arm, and in none of the patients in the dual-chamber arm (P = 0.15). New AT/AF was detected in 12 patients (24%) in the dual-chamber group, vs. no patients in the single-chamber group (P < 0.001). Among US participants, the mean cost of dual- vs. single-chamber ICD implantation was $16 579 vs. $14 249, respectively (P < 0.001); there was no difference in the quality of life (EQ-5D index difference 0.013, P = 0.769; EQ VAS difference 3.3, P = 0.49). Conclusion: When optimal programming is utilized, inappropriate shocks are rare in primary prevention patients with both single- and dual-chamber ICDs. The routine use of dual-chamber ICDs increases the expense without reducing inappropriate shocks or improving the quality of life at 1 year.