Abstract 15130: The Role of Myocardial Contrast Echocardiography in Identifying the Burden of Myocardial Ischemia in Coronary Artery Disease
BACKGROUND Myocardial contrast echocardiography (MCE) is an emerging non-invasive technique for the diagnosis of coronary artery disease (CAD). Previous studies confirm the ability of MCE to detect significant coronary stenosis. However, an important clinical requirement is identifying not only the presence of myocardial ischemia but also its extent. In this study, we evaluated the ability of MCE to quantify ischemia burden, using cardiovascular magnetic resonance (CMR) imaging as the reference standard.
METHODS Sixty-two patients with suspected CAD underwent MCE with myocardial volume imaging at rest and at stress (140mcg/kg/min intravenous adenosine). Images were visually interpreted, and ischemia identified by the presence of reversible wall motion and/or perfusion abnormalities at the segmental level. Multi-parametric high field strength (3 Tesla) CMR was also performed, with concurrent visual analysis of perfusion and late gadolinium enhancement (LGE) images. Ischemia was defined by the presence of stress perfusion defects of larger spatial extent than resting perfusion defects or LGE in the corresponding segments.
RESULTS Using CMR as the reference standard, 27/62 patients (44%) had myocardial ischemia. MCE correctly identified 80% of patients with subendocardial perfusion defects (<50% transmural extent) and 92% of patients with defects >50% transmural extent (overall sensitivity 85%, specificity 74% and diagnostic accuracy 79%). At the per vessel level, MCE identified ischemia with diagnostic accuracy 87%, sensitivity, 76% and specificity, 89%. However, at the segmental level, MCE underestimated ischemia burden (2.4±1.4 abnormal segments/patient versus 4.0±2.2 segments/patient for CMR, p<0.0001). Whereas CMR identified ischemia roughly equally at all three levels of the heart (35% - basal, 39% - mid-ventricular and 28% - apical), most MCE-defined ischemia was at the apical level (65% versus 15%/19% at basal/mid-ventricular levels).
CONCLUSION MCE achieves favorable accuracy in identifying myocardial ischemia, even when confined to the subendocardial layer. However, there is evidence of underestimation of ischemia burden indicating the need to incorporate optimization techniques to improve basal segment imaging.
- © 2011 by American Heart Association, Inc.