Background: The aim of this study was to investigate the incidence, reversibility, and severity of LV perfusion abnormalities in patients with isolated myocardial bridges using a gated myocardial perfusion SPECT study (GSPECT).
Methods: A retrospective study involved 42 patients without history of myocardial infarction, with isolated myocardial bridges detected in coronary angiography and no substantial evidence of atherosclerotic changes in coronary arteries. In all patients a gated SPECT study was performed at both rest and stress, after intravenous administration of (99m)Tc MIBI. Reconstructed slices were analyzed using a 20-segment model of the left ventricle.
Results: Incidence and severity of stress-induced ischemia were related to degree of artery constriction (P = .002 and .00014, respectively). Perfusion abnormalities were detected only in patients with critical narrowing (≥ 50%) of artery (in 12 out of 28, i.e., 43% of patients). Summed stress scores (SSS) ranged from 4 to 11 (mean 7), indicating slight or moderate defect intensity. Only 1 patient presented with a SSS value of 31 (severe defect). Perfusion defects were stress induced in 70 out of 72 (97%) segments with abnormal perfusion.
Conclusion: Perfusion abnormalities were observed in ab. 40% of patients with critical (≥ 50%) narrowing of artery affected by bridging and were mild, stress induced.