Echocardiographic Algorithm for Post–Myocardial Infarction LV Thrombus

Abstract

Objectives To determine prevalence of post-MI LV thrombus in the current era, and develop an effective algorithm – predicated on echocardiography (echo) - to discern patients warranting further testing for thrombus via delayed-enhancement (DE-) CMR. Background LV thrombus impacts post-MI management. DE-CMR provides thrombus tissue characterization and is well validated but an impractical screening modality for all post-MI patients. Methods Same day echo and CMR were performed via a tailored protocol, which entailed uniform echo contrast (irrespective of image quality) and dedicated DE-CMR for thrombus tissue characterization. Results 201 patients were studied; 8% had thrombus via DE-CMR. All thrombi were apically located – 94% occurred with LAD MI. Whereas patients with thrombus had more prolonged chest pain and larger MI (p≤0.01), only 18% had aneurysm on echo (cine-CMR 24%). Non-contrast (35%) and contrast echo (64%) yielded limited sensitivity for thrombus on DE-CMR. Thrombus was associated with stepwise increments in basal → apical contractile dysfunction on echo and quantitative cine-CMR; echo-measured apical wall motion score was higher among patients with thrombus (p<0.001) and paralleled cine-CMR decrements in apical EF and peak ejection rates (both p<0.005). Thrombus-associated decrements in apical contractile dysfunction were significant even among patients with LAD infarction (p<0.05). Echo-based apical wall motion score improved overall performance (AUC 0.89±0.44) for thrombus compared to EF (AUC 0.80±0.61; p=0.01): Apical wall motion partitions would have enabled all patients with LV thrombus to be appropriately referred for DE-CMR (100% sensitivity and negative predictive value), while avoiding further testing in over half (56–63%) of patients. Conclusions LV thrombus remains common especially after LAD MI, and can occur even in absence of aneurysm. Whereas DE-CMR yields improved overall thrombus detection, apical wall motion on non-contrast echo can be used as an effective stratification tool to identify patients in whom DE-CMR thrombus assessment is most warranted.