Background: Chagas heart disease (ChHD) is strongly linked to sudden cardiac death (SCD). The Rassi score is currently the only used clinical score with a strong association with mortality, but it lacks specificity when identifying individuals at risk of SCD. Ventricular restitution dynamics, a key factor in SCD occurrence, are difficult to assess on a large scale due to invasiveness and cost. Therefore, this study aims to develop ECG-based indices for ventricular restitution and evaluate their correlation with SCD risk in ChHD patients. Methods: We analyzed 24-hour ECG recordings from 145 ChHD patients, among whom 41 had the primary SCD endpoint within the follow-up period. We derived ECG restitution indices quantifying changes in QT and T-peak-to-end intervals (Tpe) with heart rate (∆αQT and ∆αTpe), as well as changes in the overall T-wave morphology (TMR), or Tpe morphology (TpeMR). We then evaluated the association of these indices with SCD using survival analyses. Results: Upon comparison between SCD and non-SCD groups, significant differences in clinical variables were found for Rassi score (p < 0.001), ∆αTpe (p=0.015) and TpeMR (p=0.033). Univariate Cox analysis revealed that ∆αTpe > 0.0269 and TpeMR > 0.0254 outcomes were associated with SCD risk, with a hazard ratio of 2.57 (95% [CI]: 1.34-4.91; p = 0.004) and 2.38 (95% CI: 1.25-4.50; p = 0.007), respectively. Multivariate Cox proportional hazard model was constructed by adjusting Rassi Points and only ∆αTpe > 0.0269 showed a significant hazard ratio (2.22; p =0.016). Conclusions: This study demonstrates that ECG indices assessing late-phase ventricular repolarization restitution serve as robust and independent predictors of SCD in ChHD. The fact that TMR and ∆αQT weren't associated with SCD suggest that ChHD may have other effects on ventricular repolarization, manifested on the earlier part of the T-wave, which masks the arrhythmogenic substrate specifically linked to SCD.