Significance of exercise-induced ST-segment elevation and T-wave pseudonormalization for improvement of function in healed Q-wave myocardial infarction

Abstract

Exercise-induced ST-segment elevation and pseudonormalization of negative T waves (ST-T segment changes) in infarct leads indicate myocardial viability after Q-wave myocardial infarcts in some patients and may therefore identify patients who will benefit from revascularization. Global left ventricular ejection fraction and wall motion abnormalities of the left ventricle were analyzed in 34 patients with healed myocardial infarction (11 patients with ST-segment elevation, 3 patients with pseudonormalization of the negative T wave (group 1), and in 20 patients without ST-T segment changes during an exercise electrocardiogram (group 2)) before and 4 months after successful revascularization. Wall motion abnormality in the central infarct region at baseline was similar in both groups (-3.1 +/- 0.6 SD vs 3.0 +/- 0.8 SD; NS). At repeat angiography, wall motion abnormality improved significantly from -3.1 +/- 0.6 SD to -2.1 +/- 0.6 SD (p <0.01) in group 1 and was unchanged in group 2 (-3.0 +/- 0.8 SD vs -2.9 +/- 0.7 SD; NS). Similarly, ejection fraction at control angiography had increased from 54 +/- 14% to 66 +/- 12% (p <0.01) in group 1, but decreased from 56 +/- 9% to 55 +/- 9% in group 2 (NS). Exercise-induced ST-T segment changes yielded a sensitivity of 80% and a specificity of 89% to predict significant improvement of the left ventricular ejection fraction. Exercise-induced changes of the ST-T segment identify patients with a high probability of improvement of myocardial function after revascularization in patients with healed myocardial infarcts.