Improved Detection of Echocardiographically Occult Left Ventricular Thrombi Following ST-elevation Myocardial Infarction.

OBJECTIVES: The aim of this study was to investigate predictors of TTE-occult LV thrombi and to propose a clinical model for improved detection of TTE-occult LV thrombi post ST-elevation myocardial infarction (STEMI).

BACKGROUND: Patients with acute STEMI are at significant risk for developing left ventricular (LV) thrombi. However, this complication often (up to 65%) remains undetected by using transthoracic echocardiography (TTE), referred to as TTE-occult LV thrombus.

METHODS: In total, 870 STEMI patients underwent TTE and cardiac magnetic resonance (CMR), the reference method for LV thrombus detection, 3 days after infarction. Clinical (body mass index, peak cardiac troponin T) and echocardiographic (ejection fraction, apical wall motion scores) predictors were analyzed. Primary endpoint was the presence of TTE-occult LV thrombus identified by CMR Imaging.

RESULTS: From the overall cohort, 37 patients (4%) showed an LV thrombus by CMR. Of these thrombi, 25 (68%) were not identified by TTE. TTE-occult thrombi did not significantly differ in volume (1.4 vs. 2.74cm3), diameter (19.0 vs. 23.3 mm), number of fragments or shape compared with TTE-apparent LV thrombi (all p>0.05). For predicting these TTE-occult LV thrombi, apical wall motion score using the 16-segment model (AWMS16Seg) showed highest validity (area under the curve:0.91 [95%CI:0.89-0.93]; p<0.001), with an association independent of ejection fraction and AWMS17Seg (odds ratio: 1.68 [95%CI:1.43-1.97]; p<0.001), clinical (body mass index, peak troponin) and angiographic (culprit lesion, post-interventional TIMI flow) associates of TTE-occult LV thrombi (all p<0.05). Dichotomization at AWMS16Seg ≥8 (n=260, 30%) allowed for a detection of all TTE-occult LV thrombi (sensitivity:100%), with a corresponding specificity of 77%.

CONCLUSIONS: After acute STEMI, AWMS16Seg served as simple and very robust predictor of TTE-occult LV thrombi. An AWMS16Seg-based algorithm to identify patients for additional CMR imaging offers great potential to optimize detection of TTE-occult LV thrombi following STEMI.