Background: Tissue Doppler echocardiography-derived strain rate and strain measurements (SDE) are new quantitative indices of intrinsic cardiac deformation. The aim of this study was to validate and compare these new indices of regional cardiac function to measurements of 3-dimensional myocardial strain by tagged MRI.
Methods and results: The study population included 33 healthy volunteers, 17 patients with acute myocardial infarction, and 8 patients with suspected coronary artery disease who were studied during dobutamine stress echocardiography. Peak systolic myocardial velocities were measured by tissue Doppler echocardiography, peak systolic strain rates and strains by SDE, and strains by tagged MRI. In healthy individuals, longitudinal myocardial Doppler velocities decreased progressively from base to apex, whereas myocardial strain rates and strains were uniform in all segments. In patients with acute infarction, abnormal strains clearly identified dysfunctional areas. In infarcted regions, SDE showed 1.5+/-4.3% longitudinal stretching compared with -15.0+/-3.9% shortening in remote myocardium (P<0.001), and radial measurements showed -6.9+/-4.1% thinning and 14.3+/-5.0% thickening (P<0.001), respectively. During dobutamine infusion, longitudinal strains by SDE increased significantly from -13.5% to -23.8% (P<0.01) and radial strains increased from 13.1+/-3.1% to 29.3+/-11.5% (P<0.01). Comparisons between myocardial strains by SDE and tagged MRI in healthy individuals (n=11), in infarct patients (n=17), and during stress echo (n=4) showed excellent correlations (r=0.89 and r=0.96 for longitudinal and radial strains, respectively, P< 0.001).
Conclusions: The present study demonstrates the ability of Doppler echocardiography to measure myocardial strains in a clinical setting. Myocardial strains by Doppler may represent a new powerful method for quantifying left ventricular function noninvasively in humans.