Comparison of anti-ischemic effects of isosorbide-5-mononitrate, metoprolol and diltiazem: a study based on serial treadmill exercise test.

A prospective double blind cross over study compared the anti-ischemic effect of 20 mg of isosorbide-5-mononitrate (IS-5-MN), 60 mg of diltiazem and 100 mg of metoprolol by performing serial treadmill tests (TMTs) following oral administration of single dose of each drug in 28 patients of ischemic heart disease with positive exercise TMT. The anti-ischemic effect of IS-5-MN, diltiazem and metoprolol was evaluated by assessing the time to onset of ischemia (400.8 +/- 41.1 vs 394.1 +/- 36.0 vs 412.7 +/- 36.6 secs respectively, all p > or = 0.05), duration of ischemia (390.9 +/- 58.5 vs 447.6 +/- 65.9 vs 419.4 +/- 58.7 secs respectively, all p > or = 0.05), duration of exercise 464.0 +/- 32.9 vs 476.8 +/- 32.5 vs 502.6 +/- 31.3 secs respectively, all p > or = 0.05) and severity of ischemia by scoring system (10.0 +/- 1.5 vs 10.7 +/- 1.4 vs 9.8 +/- 1.5 respectively, all p > or = 0.05). Thus, the present study suggests that there is no significant difference in the anti-ischemic effect of IS-5-MN, diltiazem and metoprolol and also suggests that the anti-ischemic effect of metoprolol is primarily by decreasing the heart rate while IS-5-MN and diltiazem exert anti-ischemic effect probably by decreasing oxygen demand and improving coronary blood flow.