Disparity between serotonin- and acetylcholine-provoked coronary artery spasm

Intrinsic vasoactive substances, such as serotonin and acetylcholine, are known to provoke coronary artery spasm in patients with vasospastic angina. It remains unclear, however, whether these different agents, which activate different receptors, produce spasms at the same sites in these patients. The present study was designed to clarify the disparity of receptor agonist-induced coronary artery spasms in the same patients.

We conducted sequential provocative tests of coronary artery spasm by acetylcholine, serotonin, and ergonovine in 20 patients with rest angina examined with quantitative coronary angiography.

Coronary artery spasms were provoked in all patients at 27 spastic sites. In 13 patients, ergonovine provoked spasms and in 10 of 13 patients who were diagnosed with variant angina, both acetylcholine and serotonin provoked spasms at the same sites where ergonovine also did. In 4 of 13 patients, spasms were provoked by serotonin but not by acetylcholine. In the remaining seven patients, whose spasms were induced by ergonovine, spasms were produced by acetylcholine but not by serotonin. On coronary angiography, the spastic sites for both acetylcholine and serotonin, and those for serotonin alone, were located in the proximal segments of coronary arteries, whereas the spastic sites for acetylcholine alone were located in the distal segments.

This study documented the disparity between serotonin- and acetylcholine-induced spasms. Provocative tests using agents that activate different receptors may produce coronary artery spasms at the same and/or different sites, and this disparity may reflect the clinical heterogeneity of vasospastic ischemic syndrome.