Prolonged benefit of nitroglycerin ointment on exercise tolerance in patients with angina pectoris

The effect on exercise tolerance of 2 per cent nitroglycerin ointment and placebo was studied on the bicycle ergometer in 10 patients with angina pectoris, a positive exercise test, and documented coronary artery disease. After a control stress test sufficient to produce angina pectoris and > 1 mm. horizontal or downsloping ST segment depression, nitroglycerin ointment or placebo was administered in a random, double-blinded manner and stress tests were repeated at 1 hour and 3 hours. End points for the exercise stress test were angina and 1 mm. ST segment depression. Forty-eight hours later, stress tests were again performed at 1 hour and 3 hours after administration of the alternate preparation. Work load (watts) plus duration of exercise (minutes) were calculated for each stage of the bicycle ergometer protocol and exercise tolerance was expressed as the sum of this product for all stages completed. Nitroglycerin ointment produced a significant increase in exercise tolerance from a control value of 877 ± 129 watt-minutes to 1165 ± 173 watt-minutes at 1 hour and 1040 ± 137 watt-minutes at 3 hours. Duration of exercise also increased significantly after nitroglycerin ointment from 13.7 ± 1.4 minutes in the control stress test to 16.8 ± 1.4 minutes at 1 hour and 16.3 ± 1.2 minutes at 3 hours. Exercise induced ST segment depression decreased significantly at 1 hour and 3 hours after nitroglycerin ointment but not after the placebo. The placebo produced a small, but statistically significant, increase in exercise tolerance and duration of exercise at 1 hour after its application. However, these increases were significantly smaller than the one observed after nitroglycerin ointment. No changes were observed 3 hours after application of the placebo. Double product at peak exercise was unchanged after nitroglycerin or placebo ointments at 1 hour and 3 hours. These data indicate that nitroglycerin ointment is capable of producing an improvement in exercise tolerance and a reduction in the magnitude of exercise-induced ST segment depression up to 3 hours in patients with coronary artery disease and angina pectoris.