EFFICACY OF A SINGLE DOSE OF SLOW-RELEASE ISOSORBIDE DINITRATE IN THE TREATMENT OF SILENT OR PAINFUL MYOCARDIAL-ISCHEMIA IN STABLE ANGINA-PECTORIS

A double-blind study was performed in 32 patients with stable angina pectoris to assess the effects of slow-release isosorbide dinitrate (ISDN) (a single dose of 120 mg/day) on the frequency and duration of painless and painful ischemic episodes, and on electrocardiographic changes and exercise tolerance. Forty-eight-hour electrocardiographic monitoring and treadmill exercise tests were performed before, and at 20 and 21 days of therapy. Holter monitoring showed a significant decrease in the frequency of painful and silent episodes (p < 0.001), and in the duration of painful (1,623 +/- 664 seconds vs 323 +/- 161 seconds; p < 0.001) and silent episodes (2,818 +/- 1,496 seconds vs 223 +/- 102 seconds; p < 0.001). The magnitude of painful and silent ST-segment depression was significantly reduced (2.7 +/- 0.9 mm to 0.7 +/- 0.7 mm and 2.0 +/- 1.1 mm to 0.7 +/- 0.5 mm, respectively; p < 0.001). Time of exercise testing to the onset of ST-segment depression (442 +/- 137 seconds vs 858 +/- 110 seconds; p < 0.001) or anginal pain was doubled (461 +/- 128 seconds vs 830 +/- 130 seconds; p < 0.001). The work load increased from 6 to 10 METs (p < 0.001). ISDN in a single dose of 120 mg/day is a valuable drug for stable angina pectoris, decreasing the frequency of silent and painful ischemic episodes and the magnitude of ST-segment depressions, and increasing exercise tolerance. It particularly shortened the duration of silent episodes. For patients' compliance, a once-daily dose of ISDN could be advantageous.