Transmural myocardial strain gradient: a new and robust quantitative index of left ventricular wall motion based on myocardial strain imaging.

BACKGROUND

Peak strain has been promising as an index of wall motion but it is sometimes susceptible to the image quality.

OBJECTIVE

We investigated the feasibility of a novel index, transmural myocardial strain gradient (TMSG), derived from myocardial strain M-mode imaging (TDI-Q, Toshiba) for quantifying regional systolic wall motion.

METHOD: We measured transmural myocardial strain distribution at the left ventricular lateral, posterior, inferior, septal, anteroseptal and anterior walls in the basal and midventricular short-axis images using TDI-Q. Twenty normals (35 ± 3 years) and 35 consecutive patients (63 ± 9 years) with coronary artery disease (CAD, 19 patients with old myocardial infarction, 4 patients with acute myocardial infarction, 12 patients with angina pectoris) were studied. Peak strain, endocardial- and epicardial-half strain and TMSG ((peak strain, - epicardial strain)/distance between peak and epicardial points) were obtained. Coefficient of variation (CV) of each index was calculated.

RESULTS

In control subjects, the best reproducibility of the variables was obtained for TMSG with the smallest CV (11.6%) (27.8%, 28.1%, and 35.5%, respectively for CV of peak strain, endocardial- and epicardial-half strain). All segments in control subjects and normal segments in CAD patients showed no significant difference in TMSG (15.1 ± 1.8 vs. 15.1 ± 1.6%/mm, P = ns). TMSG was the lowest for akinetic segments and highest for the normal segments (P < 0.001).

CONCLUSION

TMSG was more robust than simple strain values to quantitatively assess wall motion. This could successfully identify subtle regional differences in wall function.