Three-dimensional evaluation of dobutamine-induced changes in regional myocardial deformation in ischemic myocardium using ultrasonic strain measurements: the role of circumferential myocardial shortening.

Abstract

Early identification of myocardial ischemia during high-dose dobutamine stress (DOB) has important clinical implications. Myocardial strain imaging can evaluate regional myocardial contractility in the radial, longitudinal, and circumferential directions. The aim of this study was to assess precisely the differences in deterioration of myocardial deformation among the 3 directions in patients with newly developed myocardial ischemia during high-dose (40 microg/kg/min) DOB infusion. Color Doppler tissue 2-dimensional images were recorded during DOB infusion in 20 patients without myocardial ischemia and 25 patients with scintigraphically diagnosed myocardial ischemia caused by left anterior descending coronary artery stenosis. In the offline analysis, systolic radial strain (Sr), longitudinal strain (Sl), and circumferential strain (Sc) were determined in the anteroseptal and anterolateral left ventricular walls. In 20 patients without myocardial ischemia, the peak systolic strains significantly increased in all 3 directions during DOB infusion at rates between 5 and 10 microg/kg/min (Sr 50%-69%, Sl 27%-36%, Sc 29%-38%, all P < .01) with a greater rate of change in the Sr (1.8 and 1.9 times, respectively, P < .001) than in the Sl and Sc. However, the peak systolic strains decreased significantly during DOB infusion at rates between 5 and 10 microg/kg/min in all 3 directions (Sr 56%-35%, Sl 27%-13%, both P < .01; Sc 29%-7%, P < .001) with the greatest rate of change in the Sc in 25 patients with newly developed myocardial ischemia. In conclusion, circumferential myocardial shortening deteriorated to a greater extent during DOB infusion in patients with coronary artery stenosis, and its measurement is a promising tool for detecting newly developed myocardial ischemia.