Isolated negative T waves as independent predictors of short-term and long-term coronary heart disease mortality in men free of manifest heart disease in the Seven Countries Study.

ABSTRACT

Isolated T-wave findings are generally considered of little importance in clinical electrocardiogram (ECG) interpretation, although a few studies have associated them with excess mortality risk. We used Cox regression models to evaluate coronary heart disease (CHD) mortality risk for isolated inverted T waves in 8713 men in the Seven Countries Study with no manifest cardiac diseases at baseline. The study population was stratified into 3 mutually exclusive groups (1) isolated inverted T waves in the absence of other codable ECG findings according to the Minnesota Code; (2) other ECG findings with or without negative T waves; and (3) no codable ECG findings, used as the reference group. Mortality follow-up of the entire cohort was performed at 5, 10, 20, 30, and 40 years. The prevalence of isolated negative T waves at baseline was low, 1.6%, in these men from working populations. The hazard ratio (HR) for CHD mortality risk after 5 years in the isolated T-wave inversion group was more than 3 times greater than that in the reference group after adjusting for age, body mass index, cigarette smoking, systolic blood pressure, serum cholesterol and cohort (HR 3.68, 95% confidence interval [1.44-9.37]). Hazard ratio declined gradually with the length of follow-up but was still at 50% excess risk at 40-year follow-up (HR 1.51, 95% confidence interval [1.12-2.05]). T waves in the isolated T-wave inversion group were "flat" or less negative than 1mm (-100 µV) in the majority (86%) of inverted T waves. We conclude that inverted T waves with even a minor degree of negativity as an isolated ECG finding in men with no evidence of heart disease predict an excess short-term and long-term risk of CHD death.