Objective ischemic evidence in patients with myocardial bridging: Ultrasonic tissue characterization with dobutamine stress integrated backscatter

Background: in this study, we investigated the sensitivities of dobutamine stress echocardiography (DSE) and integrated backscatter (IBS) in detecting ischemia in patients with symptomatic myocardial bridging (MB). Methods: Fourteen patients given the diagnosis of MB in the left anterior descending coronary artery as shown by coronary angiography were enrolled. All patients underwent DSE and stress IBS. The cyclic variation of IBS (CVIBS) was taken from the midanteroseptal, midinferior, and midposterolateral areas of the parasternal short-axis images at rest, low dose, peak dose, and recovery. The low-dose, peak-dose, and recovery CVIBS data were compared with baseline values. Results: At peak dose, hypokinesia was observed in the left anterior descending coronary artery region in two patients (14%). A significant reduction in CVIBS was detected only when compared with the baseline at peak dose in the anteroseptal wall (8.4 +/- 1.3 vs 5.9 +/- 0.8, P = .003). A significant negative correlation was found between the CVIBS and the systolic narrowing percentage (R = -0.856, P = .001) and the length of MB (R = -0.576, P = .01) in the anteroseptal wall at peak dose. Conclusions. Whereas DSE is not sufficiently sensitive in the detection of ischemia in patients with symptomatic MB, the reduction in CVIBS during DSE may be an objective sign of ischemia.