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Exertional Syncope Caused by Hemodynamically Significant Myocardial Bridging With Coronary Vasospasm
Takumi Toya1, Yoshichika Miyazaki2, Otoya Sekine2
1Department of Cardiology, NHO Tokyo Medical Center, Tokyo, Japan; Nishikoyama Toya Medical Clinic-Diabetes and Cardiovascular Care, Tokyo, Japan.
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.
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