Usefulness of power Doppler contrast echocardiography to identify reperfusion after acute myocardial infarction.

Microvascular integrity, as seen by myocardial contrast echocardiography (MCE), assesses whether myocardium has been successfully reperfused after an acute myocardial infarction. Until now this has been demonstrated only with intracoronary injection of an ultrasound contrast agent. Power Doppler imaging is a recently developed myocardial contrast echocardiographic method that counts the contrast microbubbles destroyed by ultrasounds and displays this number in color. This study sought to evaluate whether power Doppler MCE is able to visualize myocardial reperfusion during intravenous contrast injection. Thirty patients were evaluated 2 days after their first myocardial infarction during intravenous infusion of perfluorocarbon-exposed sonicated dextrose albumin (PESDA). Coronary artery angiography and single-photon emission computed tomography (SPECT) were used as reference techniques. A 16-segment left ventricular model was used to relate perfusion to coronary artery territories. Sensitivity and specificity of power Doppler MCE for segments supplied by infarct-related arteries were 82% and 95%, respectively. Accuracy of power Doppler MCE and SPECT were similar (90% vs 92% on segmental basis and 98% vs 98% on coronary artery territory basis). Two-dimensional echocardiography was repeated after 6 weeks. Segments recovering wall motion after 6 weeks were defined as stunning myocardium. Dysfunctional but perfused myocardium at day 2 after the infarction showed a better late recovery of wall motion compared with dysfunctional but nonperfused myocardium (p <0.001). In conclusion, harmonic power Doppler imaging is a sensitive and specific method for the identification of myocardial reperfusion early after myocardial infarction. It yields prognostic information for late recovery of ventricular function differentiating stunning (dysfunctional but perfused) from necrotic myocardium (dysfunctional and nonperfused).