Severe myocardial bridge presenting as paroxysmal atrioventricular block

Abstract

Chest pain complicated with electrocardiographic changes is not an uncommon scenario in emergency departments, which should be examined cautiously. We describe a 51-years-old man with a myocardial bridge of coronary artery presenting with simultaneous Mobitz type I atrioventricular block on electrocardiography. Echocardiography excluded valvular abnormality and systolic/diastolic dysfunction. Coronary angiography confirmed the diagnosis of a myocardial bridge at the middle segment of the left anterior descending artery, involving the most dominant septal perforator branch with marked systolic compression. The patient underwent coronary artery bypass grafting surgery and was followed up uneventfully at the outpatient department with medical treatment of diltiazem and clopidogrel. The present case is being reported to highlight that clinicians should be alert to such a congenital abnormality as a potential cause of repeated myocardial infarction and conduction abnormality.

Keywords: Atrioventricular block; electrocardiography; myocardial bridge; myocardial infarction.

Figure 1

(a) Baseline electrocardiography on admission demonstrating the progressive prolongation of the PR interval (arrows) on consecutive beats followed by a blocked P wave, compatible with a Mobitz type I (Wenckebach) atrioventricular block; (b) Repeated electrocardiography after coronary artery bypass grafting surgery revealing the recovery of every PR interval (arrowheads)

Figure 2

(a) Coronary angiography in the systolic phase of the left ventricle showing the myocardial bridging of the middle segment of the left anterior descending artery (arrow) with severe systolic compression involving the dominant septal perforator branch (arrowhead); (b) Coronary angiography in the diastolic phase of the left ventricle disclosing both the patent middle left anterior descending artery (arrow) and dominant septal perforator branch (arrowhead)