Intraoperative coronary angiography and fractional flow reserve measurement with dobutamine infusion in supra-arterial myotomy for a myocardial bridge: a case report

Background A myocardial bridge (MB) is a congenital coronary anomaly, wherein the epicardial coronary artery tunnels through the myocardial band. Treatment is indicated when clinical symptoms occur, and β-blockers are the first choice of treatment. Symptomatic patients refractory to medical therapy are considered for other options, including stent placement, coronary artery bypass grafting, or surgical supra-arterial myotomy. Supra-arterial myotomy is effective; however, the symptoms might persist if myocardial resection is inadequately performed. Case summary We encountered a patient experiencing exertional chest pain. Coronary angiography revealed a MB at the mid-left anterior descending artery with systolic compression. The patient's fractional flow reserves (FFRs) were 0.93 at rest and 0.72 with intravenous administration of 50 µg/kg/min dobutamine. The symptoms were refractory to drugs, and supra-arterial myotomy was performed with intraoperative coronary artery angiography, which revealed the milking effect of the residual myocardium; therefore, additional myocardial resection was performed. Postoperative coronary artery angiography showed no systolic compression, and the postoperative FFRs were 0.88 at rest and 0.92 with intravenous administration of dobutamine 50 µg/kg/min. Discussion Although surgical supra-arterial myotomy is safe and effective, inadequate myocardial resection might cause symptom recurrence. Intraoperative coronary artery angiography during the surgery can indicate whether additional resection is required. Objective assessment of ischaemia might be useful in cases with a MB, which can cause asymptomatic myocardial ischaemia and sudden cardiac death. FFRs before surgery can help in evaluating the need for surgery and for confirming the therapeutic effect and subsequent treatment.