Exercise stress electrocardiography (ECG) is a commonly used noninvasive test for detecting myocardial ischemia but has limited diagnostic accuracy for obstructive coronary artery disease (CAD). Myocardial bridging (MB), characterized by systolic compression of a coronary artery, has been increasingly recognized as a potential cause of ischemia in patients with nonobstructive coronary arteries (INOCA). This study aimed to investigate the association between MB and positive exercise stress ECG results and to assess the relationship between MB anatomical characteristics and ischemic burden. We retrospectively analysed 197 patients who underwent both exercise stress testing and coronary computed tomography angiography (CTCA) for evaluation of chest pain. MB was identified on CTCA, and its anatomical features, including length and thickness, were measured. Exercise stress ECG results were classified as positive or negative based on standard criteria. MB was present in 32% of the study population. The prevalence of positive exercise stress ECG findings was significantly higher in patients with MB than in those without MB (66% vs. 38%, P < 0.0001). Among patients without obstructive CAD, those with positive ECG findings (INOCA) exhibited the highest prevalence of MB (62%). Additionally, MB length was significantly greater in INOCA patients compared with those with obstructive CAD and positive ECG findings (20.7 ± 6.0 mm vs. 17.1 ± 5.2 mm, P = 0.047), whereas MB thickness did not differ significantly. MB is independently associated with positive exercise stress ECG findings, particularly among patients without obstructive CAD, suggesting a pathophysiological role in exercise-induced ischemia. Furthermore, MB length may contribute to the severity of ischemic burden in INOCA.
Toya et al. (Wed,) studied this question.