Interplay Between Myocardial Bridging, Atherosclerosis, and Spasm in Patients With Nonobstructive Coronary Arteries

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.

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).

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).

Epicardial vasospasm occurs most frequently in patients with both MB and moderate atherosclerosis.