Ambulatory ECG-based T-wave alternans and heart rate turbulence can predict cardiac mortality in patients with myocardial infarction with or without diabetes mellitus

ABSTRACT: BACKGROUND: Many patients who survive a myocardial infarction (MI) remain at risk of sudden cardiac death despite revascularization and optimal medical treatment. We used the modified moving average (MMA) method to assess the utility of T-wave alternans (TWA) and heart rate turbulence (HRT) as risk markers in MI patients with or without diabetes mellitus (DM). METHODS: We prospectively enrolled 248 consecutive patients: 96 with MI (post-MI patients); 77 MI with DM (post-MI + DM patients); 75 controls without cardiovascular disease (group control). Both TWA and HRT were measured on ambulatory electrocardiograms (AECGs). HRT was assessed by two parameters BOX DRAWINGS LIGHT HORIZONTAL] turbulence onset (TO) and turbulence slope (TS). HRT was considered positive when both TO GREATER-THAN OR EQUAL TO]0% and TS LESS-THAN OR EQUAL TO]2.5 ms/R-R interval were met. The endpoint was cardiac mortality. RESULTS: TWA values differed significantly between MI and controls. Post-MI + DM patients had higher TWA values than post-MI patients (58 PLUS-MINUS SIGN] 21 muV VS 52 PLUS-MINUS SIGN] 18 muV, P = 0.029). Impaired HRT--increased TO and decreased TS were observed in MI patients with or without DM. During follow-up of 578 PLUS-MINUS SIGN] 146 days, cardiac death occurred in ten patients and three of them suffered sudden cardiac death (SCD). Multivariate analysis determined that a HRT-positive outcome HR (95% CI): 5.01, 1.33--18.85; P = 0.017], as well as the combination of abnormal TWA (GREATER-THAN OR EQUAL TO]47 muV) and positive HRT had significant association with the endpoint HR (95% CI): 9.08, 2.21--37.2; P = 0.002)]. CONCLUSION: This study indicates that AECGs-based TWA and HRT can predict cardiac mortality in MI patients with or without DM. Combined analysis TWA and HRT may be a convenient and useful method of identifying patients at high risk for cardiovascular death.