Intracoronary Acetylcholine Provocation Testing　– Omission of the 20-µg Dose Is Feasible in Patients Without Coronary Artery Spasm in the Other Coronary Artery –

BACKGROUND: Based on the Japanese Circulation Society guideline of vasospastic angina, incremental doses of acetylcholine (ACh) are prescribed for coronary spasm provocation: 20 and 50 μg for the right coronary artery (RCA), and 20, 50 and 100 μg for the left coronary artery (LCA). However, the requirement for each dose of ACh has not been fully evaluated. METHODS AND RESULTS: A total of 249 patients who underwent ACh provocation test for both the RCA and LCA were included. The positive diagnosis of intracoronary ACh provocation test was defined as total or subtotal coronary artery narrowing accompanied by chest pain and/or ischemic ECG changes. Positive ACh provocation test was observed in 116 patients (47%). Patients without vasospasm in the LCA had a lower incidence of vasospasm in the RCA induced by 20 μg of ACh compared with those with vasospasm in LCA (0.8% vs. 27.5%, P<0.001). Similarly, vasospasm in the LCA induced by 20 μg of ACh was observed less frequently in patients without than with vasospasm in the RCA (6.1% vs. 26.7%, P<0.001). In all patients without vasospasm in the other coronary artery, intracoronary administration of 50 μg of ACh was performed without any complications. CONCLUSIONS: Skipping the provocation test with 20 μg of ACh in patients without coronary artery spasm in the other coronary artery may be possible. (Circ J 2016; 80: 1820-1823).