Going under the bridge: unmasking ischaemia and endothelial dysfunction of myocardial bridging: a case report

BACKGROUND: Physiological assessment of myocardial bridging prevents unnecessary interventions. Non-invasive workup or visual coronary artery compression may underestimate the underlying ischaemia associated with myocardial bridging in symptomatic patients. CASE SUMMARY: A 74-year-old male presented to the outpatient clinic with chest pain and shortness of breath on exertion. He underwent coronary artery calcium scan showing an elevated calcium score of 404. On follow-up, he endorsed progressive worsening of symptoms with chest pain and decreased exercise tolerance. He was then referred for coronary angiography that revealed mid-left anterior descending myocardial bridging with initial normal resting full-cycle ratio of 0.92. Further workup after ruling out coronary microvascular disease demonstrated abnormal hyperaemic full-cycle ratio of 0.80 with a diffuse rise across the myocardial bridging segment on pullback. Our patient also had increased spastic response to hyperaemia on angiography, supporting the presence of underlying endothelial dysfunction and ischaemia, likely contributing to his exertional symptomology. The patient was started on beta-blocker therapy with improvement in symptoms and resolution of chest pain on follow-up. CONCLUSION: Our case highlights the importance of thorough workup of myocardial bridging in symptomatic patients to better understand the underlying physiology and endothelial function after ruling out microvascular disease and consideration of hyperaemic testing if symptoms are suggestive of ischaemia.