Can nitroglycerin convert effort-induced angina in men into silent myocardial ischemia?

The relief of anginal pain with nitroglycerin may not correspond to the disappearance of ischemia. To evaluate the possible lack of the elimination of ischemia with sublingual nitroglycerin, we studied 25 male patients with stable angina pectoris who underwent exercise stress testing with recording of blood pressure, pulse, and ST-segment displacement. The stress test was repeated 30 minutes after administration of 0.4 mg of sublingual nitroglycerin. All 25 patients had angina and ischemic ST-segment changes in the first stress test. On repeat stress testing, 15 patients had angina and ST-segment changes, 2 patients had angina but no ST-segment changes, and 4 patients had no ST-segment changes and no angina. Four patients, however, had no angina but persistent ischemic ST-segment changes suggesting that angina was converted into silent ischemia. The mean exercise duration was 311 +/- 66 seconds before and 421 +/- 81 seconds after the nitroglycerin test. Peak heart rate and systolic blood pressure before the nitroglycerin stress test were 109 +/- 18 and 155 +/- 23 mm Hg; in the repeat stress test, they increased to 123 +/- 21 and 162 +/- 20 mm Hg, respectively.