Abstract 2723: Improved Detection of Subendocardial Wall Thickening Abnormalities During Dobutamine Stress with Real Time Perfusion Myocardial Contrast Echocardiography
Background. Patients with significant coronary artery disease (CAD) may exhibit abnormal myocardial perfusion during dobutamine stress echocardiography (DSE) in the absence of wall thickening (WT) abnormalities.Although the majority of resting transmural WT occurs from the subendocardial (SE) layers, we hypothesized that normal WT in the setting of significant CAD may be due to catecholamine induction of the outer epicardial layers to thicken and mask the detection of SE ischemia. The high resolution of real time perfusion echocardiography (RTPE) detects SE perfusion defects in real time, thus permitting for the first time the examination of SE wall thickening in this clinical setting.
Methods. SE perfusion defects detected with RTPE during DSE using a continuous infusion of ultrasound contrast (Definity) were examined in 25 patients with known left anterior descending stenoses (>50% by quantitative angiography). The SE % WT was measured by computing end diastolic and end systolic WT within the SE perfusion defect in the apical portion of the septum (Figure⇓), and measuring transmural WT in the same location.
Results. Transmural WT was >30% in 15 of the 25 patients (mean 51±15%) at peak dobutamine stress. However, the % WT within the SE perfusion defect in these patients was visually abnormal and averaged only 23±9% (p<0.001 compared to transmural %WT).
Conclusions. One reason for the absence of visually evident WT abnormalities during dobutamine stress imaging in patients with CAD is due to recruitment of epicardial WT. RTPE enhances both the endocardial border and the transmural border of the subendocardium in this setting, permitting the detection of masked SE ischemia.