Risk scores inconsistently predict sudden death and ventricular arrhythmias in repaired tetralogy of Fallot.

Background: Risk scores designed to predict adverse events (AEs) including sudden death and ventricular arrhythmias can guide heightened surveillance and defibrillator (ICD) implantation. Variability in risk stratification derived from differing scores and guidelines has not been examined in repaired tetralogy of Fallot (rTOF).

Objectives: We aimed to determine the consistency in risk prediction of AEs across published scoring systems in patients with rTOF without a secondary prevention ICD indication.

Methods: We undertook a retrospective review of patients with rTOF without a secondary prevention ICD indication or severe left ventricular impairment from an institutional database. Predicted AEs were calculated across 5 published scores and 3 clinical management guidelines. The prediction of a "high-risk" cohort, using a 4% predicted AE threshold, was compared across the scoring criteria. Observed AE, ICD implantation, and device complications were recorded.

Results: A total of 156 patients (median 32, interquartile range [IQR] 25-46 years; 53% female) had 4 AEs (3 sustained ventricular tachycardias [VTs], 1 sudden death) over a median of 24 months (IQR 15-36 months). In total, 41% of patients (n = 64) had risk score variability affecting assignment of high-risk status. Heterogeneity in the predicted AE risk was associated with moderate or worse right ventricular impairment or significant late gadolinium enhancement (P < .001). No criteria predicted all AEs with 2 events only predicted by 1 score. Seven ICD implants treated 3 sustained VT episodes with 3 device-related complications.

Conclusion: Risk scores are heterogeneous and imperfect for determination of those at high risk of AEs in rTOF. Use of multiple criteria alongside adjuvant stratification strategies and multidisciplinary discussion remains necessary.