Abstract
BACKGROUND: Previous evidence suggested individual associations between myocardial bridging (MB), atherosclerosis, and epicardial vasospasm. The complex interplay between these 3 identities has not been well studied in the North American population. METHODS: All patients with angina and nonobstructive coronary arteries referred for coronary angiogram who underwent invasive coronary function testing (adenosine and acetylcholine provocation testing) at 2 North American centers between March 2016 and January 2021 were included. The prevalence of epicardial spasm (new >90% stenosis after acetylcholine injection) was assessed according to the presence of MB and moderate atherosclerosis (>50% stenosis or previously stented with negative fractional flow reserve). RESULTS: In total, 472 patients were included, from whom 18.4% (n = 87) had MB and 30.5% (n = 144) had moderate atherosclerosis. The overall prevalence of epicardial spasm was 27.8% (n = 132). Epicardial spasm occurred in 43.7% (n = 38) in patients with MB vs 24.4% (n = 94) in patients without MB (P < .01), while it occurred in 39.6% (n = 57) in patients with moderate atherosclerosis vs 22.9% (n = 75) in patients with either mild or no atherosclerosis (P < .01 for each). Epicardial spasm occurred in 19.1% (n = 50) of patients with neither moderate atherosclerosis nor MB, 35.8% (n = 44) of patients with moderate atherosclerosis alone, 37.9% (n = 25) of patients with MB alone, and 61.9% (n = 13) of patients with both MB and moderate atherosclerosis (P < .01). Multivariate analysis confirmed that MB (odds ratio, 2.93; 95% CI, 1.67-5.13; P < .01) and moderate atherosclerosis were independently associated with epicardial spasm (odds ratio, 2.32; 95% CI, 1.18-4.59; P = .02). CONCLUSIONS: Epicardial vasospasm occurs most frequently in patients with both MB and moderate atherosclerosis.