The Heterogeneity of Intracoronary Acetylcholine Testing Results Showing Positivity for Either the Right or Left Coronary Artery

Background: Some cardiologists perform vasoreactivity testing on the left coronary artery (LCA) or the right coronary artery (RCA) alone.Objectives: We retrospectively analyzed the incidence of epicardial spasm (ES) and coronary microvascular spasm (CMS) in Japanese patients with unobstructed coronary artery disease on both coronary artery testing. Methods: A total of 716 consecutive patients (241 women, mean age 64.3 ± 10.6 years old) who underwent first diagnostic angiography for suspected myocardial ischemia and who had unobstructed coronary arteries (< 50%) were enrolled. For all 716 patients, complete acetylcholine (ACh) testing was performed on both coronary arteries without the administration of nitroglycerine to relieve any provoked spasm in the first artery tested. ES was defined as ≥ 90% stenosis, usual chest symptoms, and ischemic electrocardiogram (ECG) changes, while CMS was defined as < 75% stenosis, usual chest symptoms, and ischemic ECG changes.Results: Negative spasms for ACh tests were diagnosed in 370 patients (51.7%), whereas the ACh test revealed positive spasms in 346 patients (48.3%), including 314 ESs and 36 CMSs. We obtained positive ES results in 67 patients (9.4%) with only their LCAs, while we obtained positive ES results in 110 patients (15.4%) with only their RCAs. Both the RCA and LCA showed negative ES results in 402 patients (56.1%), whereas both showed positive ES results in 137 patients (19.1%). In contrast, 10 patients (1.4%) had CMS in just their RCA, while 22 patients (3.1%) had CMS in just their LCA. Both the RCA and LCA showed negative CMS results in 680 patients (94.9%), whereas both showed positive CMS results in 4 patients (0.6%).Conclusions: We found heterogeneity in ACh testing results in the clinic because some cases were positive for the LCA while some were positive for the RCA alone.