Clinical and angiographical characteristics of acetylcholine- induced spasm: relationship to dose of intracoronary injection of acetylcholine

OBJECTIVES: The purpose of this study was to clarify clinical and angiographical characteristics of acetylcholine (ACh)-induced spasm in the right and left coronary artery. METHODS AND RESULTS: We performed 557 consecutive procedures of spasm provocation tests of ACh from January 1991 to December 2000 in patients without significant stenosis. ACh was injected in incremental doses of 20, 50 and 80 microg into the right coronary artery and in incremental doses of 20, 50 and 100 microg into the left coronary artery if spasm had not been provoked. Coronary spasm was defined as positive with more than 99% transient luminal narrowing. Proximal spasm was defined as that of segments 1, 2, 5, 6, 7 and 11 and distal spasm as that of segments 3, 4, 8, 9, 12, 13 and 14. Low-ACh-dose-induced spasms showed the clinical findings and angiographical characteristics of higher incidence of variant angina, proximal spasms, focal spasms, more ST elevation and ischemic heart disease. In contrast, angiographical characteristics of high-Ach-dose-induced spasms were distal spasms and diffuse spasms and there was less variant angina and less ST elevation. CONCLUSIONS: Lower ACh doses induced spasms more proximally and focally in the coronary artery, while higher doses of ACh provoked spasms more distally and diffusely.