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Introduction and objectives: Sudden cardiac arrest (SCA) is a significant complication in the spectrum of Chagas cardiomyopathy (CC) among infected individuals. Although the Rassi score (RS) is the most established tool for predicting mortality, a nonnegligible proportion of low- or intermediate-risk CC patients still experience SCA. This study aimed to evaluate whether electrocardiogram (ECG)-derived ventricular repolarization indices, when combined with the RS, improve SCA risk stratification in low- or intermediate-risk CC patients.

Methods: We analyzed 24-hour ECGs from 144 chronic CC patients to derive QT (ΔαQT), T-peak-to-end (ΔαTpe), T-wave morphology (TMR), and T-peak-to-end morphology (TpeMR) restitution indices.Cox regression models, adjusted for RS, assessed the independent predictive value of each index for SCA. A combined risk model was developed by combining the strongest predictors with RS.

Results: ΔαTpe showed the strongest association with SCA (P < .001) and remained an independent predictor alongside RS and hypertension (HR, 13.6; P = .020). The combined risk model improved sensitivity, balanced accuracy, and negative predictive value for identifying high-risk patients compared with RS alone, although it showed a reduction in specificity and positive predictive value. Moreover, the combined risk model maintained overall discrimination (HR, 23.1 vs RS alone HR, 17.8; both P < .001), providing complementary prognostic information.

Conclusions: ΔαTpe was independently associated with SCA risk in CC. Its combination with the RS improved the identification of high-risk patients but was less effective at detecting low-risk individuals, suggesting a complementary rather than superior role to the RS.