Background: Patients with catecholaminergic polymorphic ventricular tachycardia (CPVT) are at risk for arrhythmic events (AEs). Risk factors for AEs in CPVT are ill defined.
Objective: To develop and internally validate a risk model for AEs in a large cohort of patients with CPVT.
Methods: Data was derived from the International CPVT Registry, a retrospective multi-center cohort study. We collected baseline characteristics and follow-up data. AEs were defined as arrhythmic syncope, appropriate ICD shock, aborted cardiac arrest, and sudden cardiac death. Nine pre-specified predictors were included in the analysis. Missing data were imputed. The Cox model with internal validation using bootstrapping was used to calculate the risk. Predictors with a univariate P value <0.2 were included in the multivariable model, variables selected in >60% of bootstrap samples were included in the final model. β-estimates were used to calculate a risk score.
Results: The cohort consisted of 898 patients from 26 centers (46% male, 41% proband, 52% symptomatic at diagnosis, median age at diagnosis 16.7 [interquartile range [IQR] 10.3-38.1] years). During 4.6 (IQR 1.7-7.8) years of follow-up, 147 patients (16%) experienced an AE. Five predictors of AEs were selected for the final model and are shown in the table. The average model has a C-index of 0.79 and calibration slope of 1.03 (95% CI 0.8-1.3). The median risk score was 78 points (37-141). Predicted five-year risk of an AE was < 5% for patients with a risk score < 70 points, and > 20% for scores > 199.
Conclusion: This risk model using readily available parameters identifies the patient at both low and high likelihood for a CPVT-associated arrhythmic event.