The clinical application value of myocardial perfusion imaging in evaluating coronary artery myocardial bridge patients with symptoms

Objective: Myocardial bridge is a common inborn coronary artery anomaly, myocardial bridge may be associated with myocardial ischemia. Only a few patients with coronary artery myocardial bridge were evaluated with nuclear medicine techniques. The aim of this study was to investigate the role of nuclear cardiology with myocardial perfusion technique in symptomatic myocardial bridge patients. Methods Nineteen myocardial bridge patients with the symptoms of chest pain and chest distress were analyzed retrospectively. 99Tcm-methoxyisobutylisonitrile (MIBI) myocardial perfusion images (both exercise and rest) were performed in all. Imaging results were compared with the results of movement electrocardiogram (ECG) and coronary arteriography. The t test or χ2 test was used to statistically analyze the data with Stata 7.0 software. Results: Of the 19 patients, 18 patients had myocardial bridge locating at the left anterior descending artery, 1 patient at the left anterior descending and left circumflex artery, the mean angiographic systolic occlusion within the myocardial bridge was (65.4 ± 22.1)%. Of these 19 patients, Exercise-rest 99Tcm-MIBI myocardial perfusion imaging defined positive myocardial ischemia in 10 and negative in 9 patients. Of the 10 patients with 99Tcm-MIBI myocardial perfusion imaging defined myocardial ischemia, 8 had reversible radioactive defect of partial anterior wall and (or) apex, 1 had reversible defect of post lateral wall and post septal wall, and 1 had reversible defect of inferior wall. The positive predictive value of myocardial perfusion imaging was 52.6% (10/19), which was higher than movement ECG [21.1% (4/19), χ2= 4.07, P < 0.05]. Of the 19 cases, according to the Nobel grading, 5 cases with grade I stenosis, one was 99Tcm-MIBI myocardial periusion imaging defined myocardial ischemia. Six cases with Grade II stenosis, two were 99Tcm-MIBI myocardial perfusion imaging defined myocardial ischemia. Eight cases with Grade III stenosis, seven were 99Tcm-MIBI myocardial perfusion imaging defined myocardial ischemia. The mean angio- graphic systolic occlusion within the myocardial bridge was significantly higher in patients with myocardial ischemia on myocardial perfusion imaging than in those with normal myocardial perfusion imaging [(78.0 ± 4.7)% vs (52.8 ± 6.7)%, t=3.06, P<0.01], the lengths of myocardial bridges had no difference in patients with myocardial ischemia compared with those with normal myocardial perfusion imaging [(15.1 ± 2.1) mm vs(11.8 ± 1.0) mm, t=1.43, P>0.05]. Conclusion: 99Tcm-MIBI myocardial perfusion imaging had higher detection rate of myocardial bridging than movement ECG in symptomatic patients. (authors)