Echocardiography-quantified myocardial strain-a marker of global and regional infarct size that stratifies likelihood of left ventricular thrombus.

Abstract

Myocardial strain provides a novel means of quantifying subtle alterations in contractile function; incremental utility post-MI is unknown. To test longitudinal-quantified by postprocessing routine echo-for assessment of MI size measured by cardiac magnetic resonance (CMR) and conventional methods, and assess regional and global strain (GLS) as markers of LV thrombus. The population comprised of patients with anterior ST-segment MI who underwent echo and CMR prospectively. Preexisting echoes were retrieved, re-analyzed for strain, and compared to conventional MI markers as well as CMR-evidenced MI, function, and thrombus. Seventy-four patients underwent echo and CMR 4±1 weeks post-MI; 72% had abnormal GLS. CMR-quantified MI size was 2.5-fold larger and EF lower among patients with abnormal GLS, paralleling 2.6-3.1 fold differences in Q-wave size and CPK (all P≤.002). GLS correlated with CMR-quantified MI (r=.66), CPK (r=.52) and Q-wave area (r=.44; all P≤.001): Regional strain was lower in the base, mid, and apical LV among patients with CMR-defined transmural MI in each territory (P<.05) and correlated with cine-CMR regional EF (r=.53-.71; P<.001) and echo wall motion (r=.45-.71; P<.001). GLS and apical strain were ~2-fold lower among patients with LV thrombus (P≤.002): Apical strain yielded higher diagnostic performance for thrombus (AUC: 0.83 [0.72-0.93], P=.001) than wall motion (0.73 [0.58-0.88], P=.02), as did global strain (0.78 [0.65-0.90], P=.005) compared to LVEF (0.58 [0.45-0.72], P=.41). Echo-quantified longitudinal strain provides a marker of MI size and improves stratification for post-MI LV thrombus beyond conventional indices.