External Validation of a Risk Prediction Model for Ventricular Arrhythmias in Arrhythmogenic Right Ventricular Cardiomyopathy.

Unstructured abstract The new 5-years ventricular arrhythmia (VA) occurrence risk model is a major breakthrough for arrhythmic-risk stratification in the challenging ARVC population. In the original study, the model resulted in a 20.6% reduction in implantable cardioverter-defibrillator (ICD) placement as compared with the 2015 consensus, for the same protection level. However, only internal validation was performed, limiting generalization. Here, we externally validated the model in a European tertiary care cohort of 128 ARVC patients with restrictive indications for primary prevention ICD placement. Overall, 74% were men, none had VA history and a single patient had an ICD at baseline. Median age at diagnosis was 38 years (interquartile range [IQR] [28–50]). During a median follow-up of 7.8 years [IQR (6.1–9.7)], 15 (12%) patients experienced VA. The model provided good discrimination, with a C-index for 5-year VA risk prediction of 0.84 [95% confidence interval (0.74–0.93)] (Figure 1). However, the model led to an overestimation of the 5-year VA risk when applying thresholds