Should the Right Coronary Artery Be Routinely Assessed During Provocative Spasm Testing?

Background/Objectives: The diagnosis of coronary artery spasm (CAS) frequently requires invasive provocation testing, typically utilising acetylcholine (ACh). Although the left coronary artery (LCA) is routinely assessed as a part of the testing protocol, assessment of the right coronary artery (RCA) is often avoided since it requires the insertion of a temporary pacing wire. We sought to compare the prevalence of inducible CAS in the LCA and RCA, among patients with CAS undergoing multivessel spasm provocation testing with ACh. Methods: A local multi-institutional ANOCA (angina and non-obstructive coronary arteries) database was analysed, which included 316 patients with angina and suspected CAS who underwent provocation testing (single vessel n = 266, multivessel n = 50) with incremental bolus doses of intracoronary ACh (25, 50, 100 μg in the LCA; 25, 50 μg in the RCA). CAS was defined as >90% constriction of the epicardial coronary artery as assessed visually on coronary angiography. Results: In the 50 patients (55 ± 10 years, 77% female) who underwent multivessel spasm provocation testing, CAS was induced in 20 patients (40%), with ACh provoking CAS only in the LCA system in 45%, only in the RCA system in 35%, and both LCA/RCA in 20%. Conclusions: These findings demonstrate that assessing only the LCA may miss up to one-third of CAS cases. Therefore, it is essential to routinely evaluate the RCA, particularly when no inducible spasm is detected in the LCA.