Abstract 3416: Incremental Diagnostic Utility of Contrast-Enhanced MRI (CE-MRI) vs Contrast Echocardiography for Detection of Left Ventricular Thrombus: Morphologic Predictors of Improved Thrombus Detection by CE-MRI in Patients with Systolic Dysfunction
Background Accurate detection of left ventricular thrombus (LVT) affects clinical management of at risk pts. CE-MRI identifies LVT based on tissue characteristics and has been validated as a highly sensitive technique that improves LVT detection vs non-contrast echo. However prior comparative studies were performed without echo contrast agents, which can improve echo LVT detection. We studied diagnostic performance of contrast (C-ECHO) and non-contrast echo (NC-ECHO) vs a reference of CE-MRI for LVT detection.
Methods We prospectively enrolled pts with ejection fraction (EF) <50% referred for CE-MRI (1.5 T) to evaluate for LVT. NC-ECHO and C-ECHO (Definity; perflutren lipid microspheres) were performed within 7 (mean 1.2 ± 1.6) days of CE-MRI. Studies were interpreted blinded to results of the other modality. LVT were scored for location, volume and type (mural or intracavitary). EF was measured by cine-MRI planimetry. Cine and CE-MRI were scored via a 17 segment model to quantify wall motion and scar.
Results 80 pts were studied (age 63 ± 13, 90% CAD, NYHA 2.4 ± 0.7). CE-MRI identified LVT in 25 pts (31%). 84% of LVT were apically located; 32% were mural. All LVT were adjacent to myocardial scar. Pts with LVT by CE-MRI had larger transmural scar size (25 vs 16% of LV segments; p = 0.01) but similar EF (30 vs 33%; p = 0.4) and wall motion score index (2.3 vs 2.1; p = 0.4) to those without LVT. C-ECHO had nearly 2 fold higher diagnostic sensitivity (p = 0.02) and improved accuracy (p = 0.02) vs NC-ECHO (table⇓). However, C-ECHO did not detect 32% of LVT identified by CE-MRI. LVT missed by C-ECHO were more likely to be mural (p < 0.01). Apically located LVT were more likely to be missed when small (0.9 vs 4.1 cm3; p = 0.01) while detection of non-apical LVT was independent of size.
Conclusions While echo contrast improves diagnostic performance for LVT, a substantial number of LVT identified by CE-MRI are not detected by C-ECHO. LVT missed by C-ECHO are typically mural in shape or, if apical, small in volume.