Echocontrastographic evaluation of reperfusion will be carried out on day 7. Echocontrastographic definition of no reflow is, according to previously described methods, when > 25% of dysfunctioning segments had reduced or absent opacification (score 2-3). The technique has been described elsewhere. Briefly, myocardial contrast echocardiography studies will be performed using real-time contrast pulse sequencing operating on a Sequoia ultrasound system (Siemens, Malvern, Pennsylvania). Contrast pulse sequencing is a novel real-time MCE method that, thanks to the analysis of non-linear response of contrast bubbles in fundamental and higher harmonics, is able to provide an image with excellent signal-to-noise ratio and with particularly high sensitivity and penetration using a very low mechanical index. A second-generation ultrasound contrast agent Sonovue (Bracco, Milan, Italy) will be administered intravenously (5 ml at 1 ml/min). Myocardial opacification at MCE will be visually assessed in each of the 16 myocardial segments and semiquantitatively scored. Single perfusion score will be assigned on the basis of both the change in myocardial signal intensity throughout the replenishment curve and the degree of opacification at the peak contrast effect. Scores were graded as 1 = normal, 2 = reduced, or 3 = absent opacification. A contrast score index (CSI) will be calculated by the sum of MCE score in each segment divided by the total number of segments..