Ventricular gradient as a risk factor in survivors of acute myocardial infarction

The total cosine between R and T (TCRT) (angular difference between the spatial QRS and T wave loops) is a technical elaboration of the concept of ventricular gradient (VG), whose power as a risk stratifier in post-MI patients has already been demonstrated. Recently, it was reported that TCRT differed significantly between healthy men and women, which suggested that its predictive power might be gender dependent. The aim of the study was to investigate TCRT and its association with cardiac mortality in male and female survivors of acute MI. TCRT was measured from digital Frank orthogonal XYZ-lead ECGs recorded before hospital discharge in 681 survivors of acute MI (82% men, age: men 57.0 +/- 8.4 years, women 59.6 +/- 8.1 years, P = 0.002). During a follow-up censored at 5 years, cardiac mortality rates were 9.7% and 12.1% in men and women, respectively (P = 0.42). There were no significant difference in TCRT between men and women (-0.150 +/- 0.704 vs -0.070 +/- 0.731, P = 0.26). In univariate Cox regression analysis, TCRT < -0.88 was related to a 5-year cardiac mortality in men (relative risk [RR] 3.67, 95% confidence interval [CI] 2.13-6.34, P = 1.9 x 10(-6)), and women (RR 5.16, 95% CI 1.83-14.56, P = 0.0015). Depressed TCRT was strongly associated with increased long-term cardiac mortality in survivors of acute MI. Its predictive power did not differ significantly between the sexes. The role of TCRT as a risk-stratifier in post-MI patients deserves further prospective assessment in multivariate models with established risk factors.