Exertional Syncope Caused by Hemodynamically Significant Myocardial Bridging With Coronary Vasospasm.

BACKGROUND

Myocardial bridging (MB) may cause myocardial ischemia through impaired diastolic coronary perfusion and coronary vasomotor dysfunction, occasionally presenting as exertional presyncope or syncope.

CASE SUMMARY: We report 2 patients with exertional presyncope/syncope caused by hemodynamically significant MB and concomitant epicardial coronary spasm. Coronary angiography showed no obstructive disease. Acetylcholine provocation induced diffuse spasm in the mid- to distal left anterior descending artery, whereas intracoronary nitroglycerine unmasked systolic compression of a mid-left anterior descending artery MB. Dobutamine stress with resting full-cycle ratio demonstrated functionally significant ischemia and reproduced symptoms, accompanied by marked reductions in distal coronary and systemic blood pressure. Treatment with diltiazem resulted in complete symptom resolution.

DISCUSSION: MB may cause exertional syncope through stress-induced impairment of diastolic coronary perfusion, exacerbated by tachycardia and concomitant vasospasm.

TAKE-HOME MESSAGES: Comprehensive invasive vasomotor and physiological assessment is valuable for identifying clinically significant MB and concomitant coronary vasospasm in patients presenting with exertional presyncope or syncope.