Contrast-enhanced anatomic imaging as compared to contrast-enhanced tissue characterization for detection of left ventricular thrombus.

OBJECTIVES: This study sought to compare contrast-enhanced anatomic imaging and contrast-enhanced tissue characterization (delayed-enhancement cardiac magnetic resonance [DE-CMR]) for left ventricular (LV) thrombus detection.

BACKGROUND: Contrast echocardiography (echo) detects LV thrombus based on anatomic appearance, whereas DE-CMR imaging detects thrombus based on tissue characteristics. Although DE-CMR has been validated as an accurate technique for thrombus, its utility compared with contrast echo is unknown.

METHODS: Multimodality imaging was performed in 121 patients at high risk for thrombus due to myocardial infarction or heart failure. Imaging included 3 anatomic imaging techniques for thrombus detection (contrast echo, noncontrast echo, cine-CMR) and a reference of DE-CMR tissue characterization. LV structural parameters were quantified to identify markers for thrombus and predictors of additive utility of contrast-enhanced thrombus imaging.

RESULTS: Twenty-four patients had thrombus by DE-CMR. Patients with thrombus had larger infarcts (by DE-CMR), more aneurysms, and lower LV ejection fraction (by CMR and echo) than those without thrombus. Contrast echo nearly doubled sensitivity (61% vs. 33%, p < 0.05) and yielded improved accuracy (92% vs. 82%, p < 0.01) versus noncontrast echo. Patients who derived incremental diagnostic utility from DE-CMR had lower LV ejection fraction versus those in whom noncontrast echo alone accurately assessed thrombus (35 +/- 9% vs. 42 +/- 14%, p < 0.01), with a similar trend for patients who derived incremental benefit from contrast echo (p = 0.08). Contrast echo and cine-CMR closely agreed on the diagnosis of thrombus (kappa = 0.79, p < 0.001). Thrombus prevalence was lower by contrast echo than DE-CMR (p < 0.05). Thrombus detected by DE-CMR but not by contrast echo was more likely to be mural in shape or, when apical, small in volume (p < 0.05).

CONCLUSIONS: Echo contrast in high-risk patients markedly improves detection of LV thrombus, but does not detect a substantial number of thrombi identified by DE-CMR tissue characterization. Thrombi detected by DE-CMR but not by contrast echo are typically mural in shape or small in volume.