PurposeComparisons of the efficacy of dual- vs. single-chamber implantable cardioverter defibrillators (ICDs) in preventing inappropriate shocks have had contradictory results. We investigated whether dual-chamber devices have a lower risk of inappropriate shocks and the specific role of supraventricular tachycardia (SVT) discriminators.MethodsAll heart failure (HF) patients without an indication for pacing and implanted with a prophylactic ICD were recruited from the nationwide multicenter UMBRELLA registry. Arrhythmic events were collected by remote monitoring and reviewed by a committee of experts.ResultsAmong 782 patients, single-chamber ICDs were implanted in 537 (68.7%) and dual-chamber devices in 245 (31.3%). During a mean follow-up of 52.2 ± 24.5 months, 109 inappropriate shocks were delivered in 49 patients (6.2%). In the propensity-score-matched analysis, dual-chamber ICDs were related to lower rates of inappropriate shocks as compared to single-chamber devices (0.9% vs. 11.8%, p = < 0.001, log-rank test). In multivariable Cox proportional analysis, independent predictors of inappropriate shock were history of atrial fibrillation (hazard ratio (HR) = 2.78, CI 1.37–5.64, p = 0.004), chronic kidney disease (HR = 6.15, CI 2.82–13.53, p < 0.001), and non-ischemic cardiomyopathy (HR = 2.84, CI 1.54–5.23, p = 0.001). Among ICD settings, PR logic was the only discriminator independently related to a reduced risk of inappropriate shocks (HR = 0.18, CI 0.06–0.48, p = 0.001), along with an SVT limit enabled over 200 bpm (HR = 0.24, CI 0.11–0.51, p < 0.001).ConclusionsIn this nationwide cohort of primary prevention ICD-only patients, dual-chamber devices were related to lower risk of inappropriate shocks compared to single-chamber ICDs. Besides, PR logic and SVT limit > 200 bpm emerged as protective factors.