Background: Compared with transthoracic echocardiography (TTE), cardiac magnetic resonance (CMR) imaging has a considerably higher sensitivity for left ventricular (LV) thrombus detection in patients after ST-elevation myocardial infarction (STEMI). However, CMR imaging is not routinely available to screen all STEMI patients. The aim of this study was to establish a simple and robust TTE algorithm that identifies specific patients for additional CMR to optimize LV thrombus detection post-STEMI.   

Methods: In total, 659 consecutive STEMI patients underwent TTE and CMR 3 (interquartile range:2-4) days after infarction (median time difference between both modalities 0.5 days). LV ejection fraction (LVEF) and two different apical wall motion scores (AWMS), one using the 17-segment-model (AWMS_17Seg) and one using the 16-segment-model (AWMS_16Seg), were evaluated by TTE. Primary endpoint was defined as presence of LV thrombus by CMR (n=31, 5%).

Results: The AWMS_16Seg showed highest predictive value (area under the curve [AUC]:0.91 [95%CI:0.89-0.93];p<0.001), which was significantly higher (both p-values for difference:<0.05) compared to LVEF (AUC:0.84 [95%CI:0.82-0.87];p<0.001) and AWMS_17Seg (AUC:0.87 [95%CI:0.85-0.90];p<0.001)_. The relation between AWMS_16Seg and LV thrombus remained significant after adjustment for LVEF and AWMS_17Seg (odds ratio 1.65 [95%CI:1.16-2.35];p=0.006) as well as for clinical (hypertension, hyperlipidemia, peak troponin) and angiographic (culprit lesion, post-interventional TIMI flow) predictors of LV thrombus (both p<0.001). Dichotomization at AWMS_16Seg ≥8 (n=222, 34%) allowed detection of all LV thrombi (sensitivity:100%), with a corresponding specificity of 70% (negative and positive predictive value 100% and 14%, respectively).