Scintigraphic results in asymptomatic myocardial infarction patients with exercise-induced ST segment elevation

The mechanism responsible for exercise-induced ST segment elevation is debated, but heterogeneous patients were likely included in previous studies. This study was specifically aimed at investigating the clinical meaning of isolated exercise-induced ST segment elevation in asymptomatic patients with a recent acute myocardial infarction (MI).

We studied 30 patients (28 males, 2 females, mean age 62 +/- 9 years) with a recent MI who developed ST segment elevation in leads with a Q/QS wave pattern, and who did not develop angina or ST segment depression during exercise testing and did not have any history of post-infarction angina. Patients underwent bicycle 99m-Tc-sestamibi (MIBI) myocardial scintigraphy for the assessment of myocardial perfusion and of left ventricular function.

Only 7 patients (23.3%) showed reversible perfusion defects on stress MIBI myocardial scintigraphy, which were mild and of limited extension in all. There were no statistically significant differences in the main exercise variables between groups with or without stress-related perfusion defects. Signs of exercise-related left ventricular dysfunction were detected in 6 patients (20%), 3 of whom also showed reversible perfusion defects. Again, no significant differences in the main exercise variables were found between patients with or without stress-induced scintigraphic abnormalities.

In asymptomatic MI patients, isolated exercise-induced ST segment elevation in leads with a Q/QS wave pattern is unlikely to represent clinically relevant residual myocardial ischemia during exercise, thus suggesting that further diagnostic investigations are not necessary in these patients.