Prognostic value of average T-wave alternans and QT variability for cardiac events in MADIT-II patients

Background Identifying which patients might benefit the most from ICD therapy remains challenging. We hypothesize that increased T-wave alternans (TWA) and QT variability (QTV) provide complementary information for predicting appropriate ICD therapy in patients with previous myocardial infarction and reduced ejection fraction. Methods We analyzed 10-min resting ECGs from MADIT-II patients with baseline heart rate > 80 beats/min. TWA indices IAA and IAA₉₀ were computed with the multilead Laplacian Likelihood ratio method. QTV indices QTVN and QTVI were measured using a standard approach. Cox proportional hazard models were adjusted considering appropriate ICD therapy and sudden cardiac death (SCD) as endpoints. Results TWA and QTV were measured in 175 patients. Neither QTV nor TWA predicted SCD. Appropriate ICD therapy was predicted by combining IAA₉₀ and QTVN after adjusting for relevant correlates. Conclusion Increased TWA and QTV are independent predictors of appropriate ICD therapy in MADIT-II patients with elevated heart rate at baseline.