ANALYSIS OF MICROVASCULAR INTEGRITY, CONTRACTILE RESERVE, AND MYOCARDIAL VIABILITY AFTER ACUTE MYOCARDIAL-INFARCTION BY DOBUTAMINE ECHOCARDIOGRAPHY AND MYOCARDIAL CONTRAST ECHOCARDIOGRAPHY

The purpose of this study was to evaluate, in postinfarction dysfuncti oning myocardium, the relative potential of myocardial contrast and lo w-dose dobutamine echocardiography in detecting myocardial viability, and the relation between microvascular integrity, contractile reserve, and functional recovery at follow-vp. Twenty-four patients with recen t myocardial infarction were studied before hospital discharge with lo w-dose dobutamine and myocardial contrast echocardiography. In the dys functioning infarct area, wall motion score index was calculated at ba seline, during low-dose dobutamine, and at 3-month follow-up. Revascul arization of the infarct-related artery was performed if clinically in dicated. Eighteen patients (group A) had myocardial enhancement of the dysfunctioning infarct area at myocardial contrast echocardiography o f >50%, whereas the remaining patients (group B) had an increase of le ss than or equal to 50%. Wall motion score index was similar at baseli ne in groups A and B (2.6 +/- 0.4 and 2.8 +/- 0.2; p = NS), but it imp roved during low-dose dobutamine and at follow-vp only in group A (1.9 +/- 0.9 and 1.9 +/- 0.7, respectively; p <0.001 vs baseline). In grou p B, wall motion score index was 2.7 +/- 0.4 with low-dose dobutamine and 2.8 +/- 0.2 at follow-vp (p = NS vs rest). In identifying viable m yocardial segments, myocardial contrast echo had 100% sensitivity and 46% specificity, whereas low-dose dobutamine echo had 71% sensitivity and 88% specificity. Thus, microvascular integrity after acute myocard ial infarction is a fundamental prerequisite for ensuring myocardial c ontractile reserve and regional functional recovery. Myocardial contra st and low-dose dobutamine echocardiography have different, but comple mentary, diagnostic characteristics in detecting myocardial viability.