Identification of Hibernating Myocardium With Quantitative Intravenous Myocardial Contrast Echocardiography

Abstract

Background— There are currently no data on the accuracy of intravenous myocardial contrast echocardiography (MCE) in detecting myocardial hibernation in man and its comparative accuracy to dobutamine echocardiography (DE) or thallium 201 (Tl 201 ) scintigraphy. Methods and Results— Twenty patients with coronary artery disease and ventricular dysfunction underwent MCE 1 to 5 days before bypass surgery and repeat echocardiography at 3 to 4 months. Patients also underwent DE (n=18) and rest-redistribution Tl 201 tomography (n=16) before revascularization. MCE was performed using continuous Optison infusion (12 to 16 cc/h) with intermittent pulse inversion harmonics and incremental triggering (1:1 to 1:8). Myocardial contrast intensity (MCI) replenishment curves were constructed to derive quantitative MCE indices of blood velocity and flow. Recovery of function occurred in 38% of dysfunctional segments. MCE parameters of perfusion in hibernating myocardium were similar to segments with normal function and higher than dysfunctional myocardium without recovery of function ( P <0.001). The best MCE parameter for predicting functional recovery was Peak MCI×β, an index of myocardial blood flow (area under the curve, 0.83). MCE parameters were higher in segments with contractile reserve and Tl 201 uptake ≥60% ( P <0.05) and identified viable segments without contractile reserve by DE. The sensitivity of Peak MCI×β >1.5 dB/s for recovery of function was 90% and was similar to Tl 201 scintigraphy (92%) and any contractile reserve (80%); specificity was higher than for Tl 201 and DE (63%, 45%, and 54%, respectively; P <0.05). Conclusions— MCE with intravenous contrast identifies myocardial hibernation in humans. Prediction of viable myocardium with MCE is best using quantification of myocardial blood flow and provides improved accuracy compared with DE and Tl 201 scintigraphy.