Left ventricular function and functional recovery early and late after myocardial infarction: a prospective pilot study comparing two-dimensional strain, conventional echocardiography, and radionuclide myocardial perfusion imaging.

BACKGROUND

Visual left ventricular (LV) wall motion scoring is well established for the assessment of LV function, yet it is subjective, circumstantial, and relative and requires long training. Quantification of myocardial shortening (strain) using two-dimensional speckle-tracking is potentially less subjective. In this study, quantifiable LV contraction (two-dimensional strain) was prospectively cross-related with wall motion score (WMS) and radionuclide myocardial perfusion imaging (MPI) score in 20 patients (mean age, 54 ± 9 years) with acute myocardial infarctions, early and late after percutaneous revascularization.

METHODS

Echocardiography and rest MPI were performed 3 to 5 days after acute myocardial infarction. Echocardiography was repeated at 4 months. Peak segmental and global endocardial longitudinal strain (LS) and circumferential strain (CS) were measured, and principal strain was calculated. Volumes, WMS, MPI scores, and strain were assessed independently.

RESULTS

Two-dimensional strain, visual WMS, and radionuclide MPI score correlated closely. Strain thresholds for abnormal WMS were 11.7% for early LS, 18.2% for early CS, 13.9% for late LS, and 19.1% for late CS. Late principal strain correlated better with WMS and MPI score than either LS or CS. CS varied minimally over time, while LS improved in most segments. Higher early CS (>15%) was predictive of segmental functional recovery. MPI score correlated better with late rather than early strain, probably because early resting perfusion defects represent permanent damage.

CONCLUSIONS

In this pilot study, strain correlated with echocardiographic WMS and the extent of ischemia (MPI score) early and late after revascularization in patients with acute myocardial infarction. Longitudinal and circumferential strain uncoupling was observed. LS appeared to be more sensitive to acute ischemia, whereas CS correlated better with improvement after revascularization.