Effects of intracoronary administration of nitroglycerin on contralateral intracoronary acetylcholine test results.

This study examined the question of whether intracoronary administration of nitroglycerin modifies contralateral intracoronary acetylcholine test results. Acetylcholine was injected separately into both left and right coronary arteries in 63 patients with coronary spastic angina. Acetylcholine (20 and 50 micrograms) was injected first into the coronary artery responsible for the documented regional ischemia during spontaneous or induced attacks, and then into the other coronary artery. Coronary spasm was defined as severe transient coronary artery vasoconstriction with chest pain and/or electrocardiographic ischemic ST-segment deviation. Spasm was induced in either coronary artery in 60 patients (95%) and in both coronary arteries in 23 patients (37%). The frequency of induced spasm was 67% (42 of 63) in the coronary artery first challenged by acetylcholine. The coronary artery spasm subsided with the intracoronary injection of nitroglycerin (250-750 micrograms) in 19 patients. In the second challenge of intracoronary acetylcholine injection into the contralateral coronary artery, coronary spasm was induced in 29 (66%) of 44 patients. This was done without intracoronary administration of nitroglycerin in the first challenge and in 12 (63%) of 19 patients who had been given intracoronary nitroglycerin. The sensitivity for spasm induced by intracoronary acetylcholine appeared to be unaffected by nitroglycerin. Coronary spasm with ST-segment elevation by intracoronary acetylcholine in the second challenge was significantly less frequent in the patients receiving intracoronary acetylcholine in the second challenge was significantly less frequent in the patients receiving intracoronary nitroglycerin (first: 89%, second: 26%, p < 0.05) as well as in those not receiving intracoronary nitroglycerin for the spasm in the first challenge (first: 52%, second: 13%, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)