A new electrocardiographic classification for post-myocardial infarction clinical trials

A new electrocardiographic code was developed for clinical trials involving patients with acute myocardial infarction (AMI). In the Multicenter Post-Infarction Program (MPIP), the electrocardiogram, classified by the Minnesota code, was not useful as a clinical predictor and played almost no role in subsequent analysis. To test its value the new code was applied to the electrocardiograms of 653 of the 866 patients in the MPIP data base who had sustained a first AMI. The MPIP code identifies AMI by region and severity. The 4 regions are anterior, lateral, inferior and posterior, defined by traditional criteria. Severity codes include Q-wave and non-Q-wave AMI, ST depression and no ischemic changes. The interpretation for each of 4 regions results in a 4-digit location severity code that is amenable to sorting and analysis. Fourteen separate and mutually exclusive groups were identified. Mortality gradients were found within the inferior AMI groups, but not within the anterior AMI groups. Mean ejection fraction was 50% for patients with isolated anterior infarction and decreased progressively (p less than 0.0003) as the extent of lateral wall involvement increased. For isolated inferior AMI, mean ejection fraction was 53%; lateral or posterior involvement did not significantly change this. The MPIP code is easy to apply, correlates acceptably well with clinically relevant variables of left ventricular function and permits the electrocardiogram to be used as a clinical predictor in large clinical trials.