Relation of myocardial bridge to myocardial infarction: a meta-analysis

Small case series have suggested an association of coronary myocardial bridge (MB) with myocardial infarction (MI). However, the relationship between MB and major adverse cardiac events (MACE) remains largely unknown. The aim of this study was to assess the relationship between MB and MACE involving MI.

We performed a systematic search of MEDLINE, PreMEDLINE, and all EMB Reviews as well as a reference list of relevant articles according to the SPICO (Study design, Patient, Intervention, Control-intervention, and Outcome) criteria using the following keywords: myocardial bridging, myocardial bridge, intramural coronary artery, mural coronary artery, tunneled coronary artery, coronary artery overbridging, etc. Bibliographies of the retrieved publications were additionally hand searched. Studies were included for the meta-analysis if they satisfied the following criteria: (1) they evaluate the association of MB with cardiovascular endpoint event; (2) they included individuals with MB and those without MB; 3) they excluded individuals with obstructive coronary artery disease (CAD). Studies were reviewed by a predetermined protocol including quality assessment. Dates were pooled using a random effect model.

Seven observational studies that followed 5 486 patients eligible for the enrolled criteria were included from 7 136 initially identified articles. The prevalence of MB was 24.8% (1 363/5 486). During 0.5-7.0 years of follow-up of this cohort of population, crude outcome rates were 8.0% in the MB group and 7.7% in the non-MB group. The odds ratio of overall MACE and MI were 1.34 (95% confidence interval (CI): 0.57-3.17, P = 0.51, n = 7 studies) and 2.75 (95% CI: 1.08-7.02, P < 0.03, n = 5 studies) respectively for subjects of MB compared to non-MB.

Relationship between MB and MI appears to be a real one, although the study did not reveal a connection of MB to MACE, suggesting whether the necessity of antiplatelet therapy needs to be further studied in a larger cohort of patients with MB prospectively.