Tissue viability by contrast echocardiography

Residual tissue viability within the infarct area is one of the major determinants of regional functional recovery after acute myocardial infarction, playing also a protective role against LV remodelling. However, viability and functional recovery are not synonymous: functional recovery is only one of the aspects of viability. Several studies have shown how important it is to maintain perfusion independently from functional recovery. In patients with an extensive endocardial necrosis and a preserved normal perfusion in the middle and epicardial myocardium layers, even though functional recovery does not occur, remodelling processes may be attenuated. Tissue viability may be detected using several different methods. Perfusion-based techniques (i.e. PET, SPECT, MRI and MCE) are more accurate in predicting global function and LV remodelling whereas inotropic reserve-based methods (i.e. DE) are more accurate in predicting functional recovery. Several studies support the hypothesis that either LV remodelling or the possibility of myocardial dysfunction to recover are strictly dependent on the extent of microvascular damage. To date, myocardial contrast echocardiography and magnetic resonance imaging have shown to be very effective techniques for assessing microvascular perfusion. Our initial experience showed a very close correlation between these two perfusional techniques. In particular by MCE, it has been demonstrated that the persistence of residual anterograde or retrograde blood flow within the infarct zone can maintain myocardial viability for a prolonged time span. The incidence of LV remodelling is significantly tower in dysfunctioning but stilt perfused segments than in non-perfused ones. Therefore MCE can be used to identify viable segments that may help to prevent infarct expansion and remodelling, and thus improve patient outcomes. (C) 2006 The European Society of Cardiology. Published by Elsevier Ltd. All rights reserved.