Aims: To compare the value of serial electrocardiographic (ECG) changes by the two most widely used ECG classification systems-the Minnesota Code (MC) and Novacode (Nova) for the prediction of subsequent coronary heart disease (CHD) and total mortality.
Methods and results: We studied 12-lead ECGs from 12,477 participants (average age 54 years at baseline; 58% women; 76% non-Hispanic white) in the Atherosclerosis Risk in Communities (ARIC) Study, who were free of CHD at baseline in 1987, had both good-quality ECGs at baseline and at first study-scheduled follow-up visit, and had ECG QRS duration <120 ms. A total 2119 participants died (17%), including 280 CHD deaths during an average 17-year follow up. Cox regression models assessed outcome associated with significant serial ECG changes by MC and Nova separately. For CHD death the hazard ratio was 6.8 (95% CI 3.5-13.3) for incident Nova myocardial infarction (MI), and 5.7 (95% CI 2.7-11.9) for MC-MI in a multivariable model adjusted for clinical and demographic characteristics, and ECG left ventricular hypertrophy. The increased risk for total mortality doubled for both Nova and MC serial ECG MI. Major evolving ST-T wave abnormalities alone were associated with a ≥132% increased risk for CHD death and a 50% increased risk for total mortality by either Nova or MC.
Conclusion: ECG serial change by both MC and Nova are equally valuable predictors for future fatal cardiac events and total mortality and hence equally useful prognostic indicators in clinical trials and epidemiological studies.