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

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.

Intravenous contrast echocardiography after myocardial infarction: relationship among residual myocardial perfusion, contractile reserve and long-term remodelling.

OBJECTIVE: Previous studies have shown the potential role played by intracoronary myocardial contrast echocardiography (MCE) in predicting long-term remodelling and function after myocardial infarction (MI). Scanty data, however, are available on the role of intravenous MCE in this regard. The aim of this study was to assess the role of residual myocardial blood volume in the asynergic region in modulating ventricular volume changes over time post-MI. METHODS: Thirty-two consecutive patients with anterior MI were studied predischarge using low-dose dobutamine echocardiography (Dob) and intravenous triggered MCE. Videointensity plots were generated from the apical approach and fitted exponentially. Volumes were assessed at baseline, during Dob and at 8 months. RESULTS: Baseline volumes, which appeared related to the extent of the asynergic region (P < 0.01) but showed no relation with videointensity in that area, did not change at follow-up, although Dob had elicited significant contractile reserve. However, videointensity in the asynergic region showed a significant interaction (P = 0.044) with the change in diastolic volume over time, with patients with the highest videointensity reverting remodelling (n = 11, from 69 +/- 16 to 65 +/- 16 ml/m) as compared with the remaining population (n = 21, from 68 +/- 16 to 73 +/- 21 ml/m). This was not seen when Dob-derived parameters were used. Multivariate analysis ranked videointensity second (P = 0.066), after baseline stroke volume (P = 0.005), in predicting changes in volumes over time. CONCLUSIONS: Unlike inotropic reserve, residual myocardial blood volume in the dysfunctioning muscle, as assessed by predischarge quantitative intravenous MCE, has the potential to modulate remodelling in patients who suffered an anterior MI.