Long-term prognosis of out-of-hospital cardiac arrest due to idiopathic ventricular arrhythmias

Life-threatening ventricular arrhythmias (VA) may occur in patients with unknown cardiac disease. A sizable part of them remains labeled as idiopathic VA and limited data is available regarding their natural history. Our aim was to evaluate the longterm clinical outcomes of survivors of an idiopathic life-threatening VA. Patients who survived an idiopathic life-threatening VA referred to an ICD were included and followed for a median followup of 7 years. Clinical and device data were collected and a comparison between genders was made. A total of 29 patients, 41% female, mean age of 50 (19) years were studied; all were implanted with an ICD at index hospitalization. At follow-up, an etiological diagnosis was established in 38% of patients. Genetic testing improved the diagnosis and allowed the identification of a distinct clinical entity in 60% of patients (p=0.04, OR=7.0), especially in women. Regarding ICD data, 31% received appropriate therapies with a median time to the first appropriate shock of 39 months (IQR 12-46 months). Men had a significantly higher prevalence of appropriated shocks (50% vs 8%, p=0.04), with a similar time to the first arrhythmic event between genders. Two of the patients died, both from non-arrhythmic causes. Etiologic diagnosis and recurrence prediction in patients with idiopathic VA is challenging, even with longterm follow-up and sophisticated diagnostic evaluation. Genetic testing significantly improved the diagnostic yield, especially in women. Arrhythmia recurrence occurred in about one-third of patients and is significantly higher in men, underscoring the importance of ICD implantation.