We wanted to perform quantitative echocardiographic assessment of myocardial function in the patients with myocardial bridge by measuring 2-dimensional strain with using newly developed software.

Novel computer software was used for tracking heart tissue on echocardiography, and we conducted an advanced wall-motion analysis for 18 symptomatic patients (mean age: 57.1±9.7 years, 10 female) with myocardial bridging of the left anterior descending coronary artery and also 20 age-matched healthy controls. The conventional wall-motion scoring was normal in all the patients, and the software was able to adequately track their heart tissue.

The maximal angiographic systolic lumen diameter reduction within the myocardial bridges was 71±12.6% at rest, with a persistent diameter reduction of 31.2±11.3%. The radial strain and displacement of the anterior segments were more significantly reduced than that of the posterior segments at the level of the papillary muscle (30.9±13.8% vs. 51.8±17.3% and 4.8±0.9 vs. 5.9±1.5, respectively, all p<0.05), and this showed a plateau (39% and 33%, respectively) or biphasic (50% and 56%, respectively) pattern. The time from the R wave on electrocardiography to the transition from regional systole to early diastolic lengthening (Tr) was significantly delayed in the patients with myocardial bridge more than that for the controls (497±20.4 ms vs. 348±12.5 ms, respectively, p<0.05).

Delayed systolic contraction and diastolic relaxation are important mechanisms that contribute to ischemia in the patients with myocardial bridge. 2-dimensional strain can be used to achieve real-time wall-motion analysis, and it has the potential to improve the identification and functional quantification of myocardial Bridge.