Inappropriate ICD therapy is associated with adverse outcome. Previous studies indicated that patients with a cardiac resynchronization therapy-defibrillator (CRT-D) might have a lower risk for inappropriate device activations than patients with a single (VVI) or dual chamber (DDD) ICD.

All ICD recipients from a university cardiac center between 2000 – 2015 were included in this analysis. Outcome parameters were incidence of appropriate and inappropriate therapy and overall mortality.

A total of 1471 patients were analyzed: 629 (43%) patients with a VVI-ICD, 486 (33%) patients with a DDD-ICD and 356 (24%) with a CRT-D device. During an average follow-up of 4.1 ± 3.6 years, CRT-D patients had the lowest risk to receive at least one inappropriate shock therapy (p < 0.001). Rates of appropriate (RR (Rate Ratio) = 0.45, p = 0.019) and inappropriate shock therapy (RR = 0.38, p = 0.021) were significantly lower in CRT-D patients compared to VVI-patients. CRT-D recipients had a lower rate of appropriate shock therapy (RR = 0.323, p = 0.043) compared to DDD patients, but not of inappropriate shock therapy (p = 0.371). Kaplan Meier Analysis did not reveal a significant difference in overall survival (p = 0.396). However, after adjustment for relevant confounding factors, VVI-patients had a higher risk for overall-death (HR = 1.28, p = 0.030).

CRT-D recipients have a significantly lower rate of appropriate shock therapy and a lower rate of inappropriate shock therapy. More frequent inappropriate therapies in VVI-ICD recipients may account for their higher overall mortality.