Acetylcholine coronary spasm provocation testing: Revaluation in the real clinical practice

Background: Japanese Circulation Society guidelines for coronary spastic angina recommended the step-by-step bolus administration of acetylcholine (ACh) dose on both coronary arteries (left coronary artery (LCA): 20/50/100 µg, right coronary artery (RCA): 20/50 µg). Our routine practice employed the maximal 80 µg ACh into the RCA and 200 µg ACh into the LCA not to misdiagnose the patients with coronary spasm. At least from five to seven times procedures are necessary during ACh spasm provocation tests. Radiation exposure and the adverse effect of contrast medium is one of the problems. Objectives: We investigated the procedures of the ACh administration on both coronary arteries in the real clinical practice retrospectively. Methods: We analyzed the consecutive 150 patients who had maximal ACh dose of 200 µg into the LCA. We compared clinical issues with and without saving ACh dose. Positive spasm was defined as a transient >90% narrowing and usual chest symptom or ischemic ECG changes. Results: Among 150 patients, 63 patients (42.0%) had positive provoked spasm. Patients with step-by-step ACh dose into the LCA were significantly higher than those with step-by-step ACh dose into the RCA. Saving of ACh 20 µg, 50 µg, and 100 µg into the LCA was observed in 59 patients, 18 patients, and one patient, respectively. Saving of 20 µg ACh and 50 µg ACh into the RCA was found in 98 patients and 60 patients, respectively. Positive spasm frequency was not different between the patients with and without saving ACh procedures. Radiation exposure time/dose and total used amount of contrast medium in saving ACh tests were significantly lower than those in step-by-step ACh tests. No serious irreversible complications were found. Conclusions: We should reconsider the saving ACh spasm provocation tests in the real clinical practice.