[Myocardial contrast echography. History, methodology and clinical applications]

Abstract

Recent studies have demonstrated the usefulness of myocardial contrast echocardiography (MCE) in studying myocardial perfusion. Several first and second generation contrast agent such as Levovist, Sonovue, Optison, Definity and Imagent are commercially available or close to be introduced into the market. Use of MCE allowed the clinical demonstration of no-reflow phenomenon in patients with acute myocardial infarction (AMI) after recanalization of the infarct related artery (IRA). Coronary angiography is unable to assess the microvascular damage as showed by the poor correlation between TIMI grading and perfusion score evaluated by MCE. Furthermore, the use of MCE is important to determine coronary stenosis, to identify microvascular damage during ischaemia-reperfusion and to evaluate the presence of collateral circulation in the area at risk. MCE seems to be the most effective technique for assessing microvascular integrity after reperfusion as compared to TIMI myocardial perfusion grade, nuclear myocardial perfusion imaging and magnetic resonance imaging. These techniques are expensive, invasive and not available in most of the hospitals. Furthermore, as compared to nuclear medicine and echo-dobutamine, MCE has greater specificity and higher accuracy in detecting coronary artery disease. Recent studies showed that not only primary percutaneous coronary intervention (PCI) but also rescue and delayed PCI reduced microvascular damage and that MCE play a key role in assessing myocardial salvage after reperfusion. The most exciting aspect of MCE is the independent role in predicting left ventricular (LV) remodelling and functional recovery. The extent on no-reflow is an important predictor of LV dysfunction and remodelling at follow-up. Several studies have demonstrated that the extent of infarct-zone viability is a powerful independent predictor of LV dilation. There is a close relationship between the extent of microvascular damage, the extension of necrosis, the site of AMI and LV remodelling. We demonstrated that MCE performed 24 hours after reperfusion, at 1 week and 6 months appears to provide important prognostic information. These data support the daily use of MCE in coronary care unit and could establish a strategy for clinical decision making in patients with AMI.