Sex-related Differences in Patients with Positive Coronary Spasm as Identified by Acetylcholine Testing

OBJECTIVE: A pathological acetylcholine (ACh) test was observed at lower ACh doses in females compared with males in European populations. We retrospectively analyzed the sex-related differences in Japanese patients with provoked positive spasm by ACh spasm provocation testing. METHODS: We performed the ACh spasm provocation tests in 1,854 patients from Jan 1991 until Mar 2019. ACh was injected in incremental doses of 20/50/100/200 μg into the left coronary artery and 20/50/80 μg into the right coronary artery. Positive spasm was defined as >90% stenosis and usual chest pain or ischemic ECG changes. We compared the clinical characteristics, angiographical findings during ACh testing, and clinical outcomes between female and male patients with and without provoked positive spasm. RESULTS: Positive provoked spasm was diagnosed in 917 patients including 737 (80.4%) males and 180 (19.6%) females. The incidence of provoked positive spasm in females was significantly lower than that in males (33.5% vs. 56.0%, p<0.001). Female patients with provoked positive spasm tended to be older, have less history of smoking, less provoked spasm in the left circumflex artery, or less focal type spasm than male patients with provoked positive spasm. The incidence of ST elevation during ACh testing in male patients was significantly higher than that in female patients, whereas the frequency of ST depression in females was remarkably higher than that in males. The mean maximum used ACh dose for provoked positive spasm on both coronary arteries in female patients was significantly higher than that in male patients. The observed major complications during ACh testing did not differ substantially between the sexes. In addition, the prognosis in females with provoked positive spasm was not different from males. CONCLUSION: Provoked positive spasm by ACh test was obtained at lower mean maximum ACh doses in males compared with females in Japanese patients.