Myocardial contrast echocardiography and quantitative videointensity analysis after myocardial infarction: correlation between residual myocardial perfusion, contractile reserve and long-term remodeling.

ABSTRACT

BACKGROUND: Previous studies have shown the important role played by intracoronary myocardial contrast echocardiography (MCE) in predicting the long-term remodeling and function after myocardial infarction. The left ventricular volume is an important determinant of the clinical outcome following an acute event. No data, however, are available on the role of intravenous MCE in this regard. METHODS: Ten consecutive patients with an anterior myocardial infarction were studied using low-dose dobutamine stress echocardiography (Dob) and intravenous MCE 8 +/- 4 days after the acute event. In all patients the left anterior descending coronary artery (LAD) was identified as the infarct-related vessel. A LAD score was generated using the percent residual stenosis and its location (proximal, mid, distal portion). Quantitative myocardial videointensity plots were then generated for each of the 12 ventricular segments analyzed, while the volumes were assessed during Dob and after 8 +/- 4 months. A higher peak intensity in the dysfunctioning muscle, during intravenous MCE infusion, was assumed to reflect a greater myocardial blood volume. RESULTS: Despite no change in the wall motion score index (WMSI), the percentage changes in systolic volumes during inotropic stimulation showed a linear relation with the LAD score. Furthermore, a normalized myocardial gray level in the asynergic region, taken as the plateau value of the videointensity time curve, showed an inverse relationship with the percentage changes in systolic volumes at follow-up. CONCLUSIONS: The residual microcirculation in the dysfunctioning muscle, quantitatively assessed at intravenous MCE 8 +/- 4 days after the acute event, has the potential of predicting chronic remodeling following an anterior myocardial infarction, irrespective of changes in the WMSI. The product of the degree of the residual infarct-related artery stenosis and its proximity predicts the ventricular volume response during low-dose Dob.