The effects of isosorbide dinitrate on exercise-induced ST-segment elevation at the infarcted area in old myocardial infarction.

To clarify the clinical significance and therapeutic implication of exercise-induced ST elevation at the infarcted area in old myocardial infarction (OMI), 30 patients with exercise-induced ST elevation underwent treadmill exercise testing. The patients with transient perfusion defects at the infarcted area on thallium-201 stress myocardial scintigraphy (group I: n = 12) revealed a decreased rate of ST elevation expressed as delta ST/delta HR X 10(2) after 10 mg of isosorbide dinitrate (ISDN), compared to the results of treadmill exercise testing under no medication (3.1 +/- 2.5 vs. 4.7 +/- 2.6, p less than 0.001). Exercise capacity and anginal threshold were improved after ISDN in group I. In contrast, the patients without transient perfusion defects (group II: n = 18) revealed an increased rate of ST elevation after ISDN (2.4 +/- 1.1 vs. 2.0 +/- 0.8, p less than 0.05). It is concluded from the above results that if exercise-induced ST elevation at the infarcted area reflects transient myocardial ischemia, ISDN can decrease it by its anti-anginal effect. Additionally, treadmill exercise testing with ISDN is a useful means of clarifying the underlying pathophysiology and management in OMI cases with this effect on exercise-induced ST elevation at the infarcted area.