In this work, we evaluate and characterize the predictive potential of T-wave alternans (TWA) indices for sudden cardiac death (SCD) in a population of patients with Chronic Chagas Cardiomyopathy (CCC) with a 4-year follow-up. TWA waveforms are estimated in processable 128-beat segments using a combination of periodic component analysis (πCA) and the Laplacian likelihood ratio (LLR) method. Then, the Index of Median Alternans (V_IMA) is computed as the mean absolute voltage of the median alternans waveform. The index is computed from the complete recording and in a cumulative heart-rate (HR) strategy, from 40 to 140 bpm, restricting to those k:th segments with mean heart rate (HR_k) lower than a particular HR_b, named V_IMA_C(HR_b). SCD patients showed significantly higher values of V_IMA (0.93 vs 0.71, p=0.009) and, even more significantly, higher values of V_IMA_C(77.5) than survivor patients (0.92 vs 0.67, p = 0.006). Univariate Cox analysis showed that V_IMA and V_IMA_C(77.5) are significantly associated with SCD risk, (HaR = 2.36, 95% CI: 1.44-3.87, p=0.001) and (HaR = 2.46, 95% CI: 1.48-4.08, p < 0.001), respectively. In conclusion, TWA indices, specially computed at HR < 77.5 bpm, are strongly associated with SCD in Chagas patients.