PROGNOSTIC-SIGNIFICANCE OF ST-T SEGMENT - ALTERATIONS IN PATIENTS WITH NON-Q-WAVE MYOCARDIAL-INFARCTION

Objective-To determine whether, among patients with non-Q wave myocard ial infarction, the characteristics of the segment ST-T shifts at pres entation in the diagnostic electrocardiogram can identify those with m ore severe coronary artery disease and predict a poor clinical outcome . Design-Prospective controlled clinical trial. Setting-Primary referr al medical centre. Patients-93 patients (mean (SD) 62.0 (7.5) years) w ere studied: 41 with non-Q wave myocardial infarction and T wave inver sion and 52 with ST segment depression. Cardiac events and mortality r ates were assessed over 42 months. Age, sex, risk factors, creatine ki nase MB isoenzyme peak, and left ventricular function were comparable. Results-31 patients with T wave inversion myocardial infarction (94.6 %) had total occlusion of the infarct related artery, compared with 12 patients with ST segment depression myocardial infarction (26.7%) (P< 0.05), When compared with patients with T wave inversion, patients wit h ST segment depression had a higher incidence of cardiac events durin g the first month and in the 41 subsequent months: 9.6% and 30.8% v 0% (P<0.01) and 9.8% (P<0.02), respectively. For the same observation pe riods, the mortality rates in patients with T wave inversion were 4.9% and 7.3%, and in patients with ST segment depression they were 5.8% a nd 9.6%, respectively. Conclusion-These data suggest that during a non -Q wave myocardial infarction the presence of ST segment depression is related to higher rates of short and long term cardiac events when co mpared with T wave inversion-possibly because of a higher incidence of residual stenosis of the infarct related artery.