BACKGROUND : The occurrence of sustained ventricular arrhythmias (SVA) may be influenced by environmental factors. We aimed to investigate annual periodic trends of SVA from the intracardiac electrograms (IEGMs) stored in the implantable defibrillators (ICDs) or cardiac resynchronization therapy (CRT-D) recipients. METHODS : Data from the Home Monitoring Expert Alliance project, a pooled repository of remote monitoring transmissions were analyzed. All IEGMs stored were independently adjudicated by three cardiac electrophysiologists. Periodicity of SVA was evaluated with Generalized Estimating Equations (GEE) models, including periodic terms depending on months in a year. RESULTS : A total of 2936 ICD/CRT-D patients (median age 70 years, 79.6% male) were followed for a median period of 25[13-44] months. Most prevalent structural heart diseases were ischemic (50.8%) and idiopathic dilated (30.6%) cardiomyopathies. Overall, 942 (32.1%) patients experienced a total of 4824 SVA. At GEE analysis, we found a significant periodic component (p = 0.048) when considering both shocked and non-shocked episodes. SVA less frequently occurred in Junes and Julies (3.7 × 1000 patient-month). No evidence of significant periodicity was collected in the subgroup of ischemic patients. CONCLUSIONS : In this RM-based cohort of ICD/CRT-T patients, we observed an annual periodicity of SVA occurrence, with a lower incidence in summer months.