Relationship between function and perfusion early after acute myocardial infarction

To assess the relationship between baseline left ventricle function, functi onal reserve and resting myocardial perfusion in patients with acute myocar dial infarction (AMI). After AMI the presence of dysfunctioning but viable myocardium plays a determinant role in clinical outcome. Regional ventricul ar function was evaluated by echocardiography both in resting conditions an d during dobutamine infusion (10 mug/kg/min). Perfusion was assessed by mag netic resonance imaging in a single slice approach where the first pass of an intravenously injected bolus of gadolinium-based contrast agent was foll owed through six regions of interest within the myocardium. In each patient a region with normal function was used as reference and the cross-correlat ion coefficient (CCC), which described the myocardial perfusion relatively to the reference region (CCC = 1 means equivalent perfusion), was obtained for the other five myocardial regions. Twenty-two patients were enrolled in to the study. Sixty-one segments had normal function and normal perfusion ( CCC = 0.92 +/- 0.23). The perfusion deficit was more marked in the 29 regio ns with resting akinesia-dyskinesia than in the 20 hypokinetic regions (CCC = 0.71 +/- 0.45 vs. 0.84 +/- 0.23; p < 0.05). Out of the 29 regions with r esting akinesia-dyskinesia the 13 segments which showed functional improvem ent following dobutamine had a higher resting perfusion than the 16 segment s which were unresponsive to dobutamine (CCC = 0.83 +/- 0.32 vs. 0.61 +/- 0 .52, p < 0.05). Similarly, out of the 20 regions with resting hypokinesia t he 11 segments having functional reserve showed an higher resting perfusion than the segments which did not (0.96 +/- 0.21 vs. 0.69 +/- 0.19; p < 0.05 ). Early after AMI, the perfusion deficit reflects the severity of the mech anical dysfunction. In regions with baseline dyssynergy resting perfusion i s, in general, higher when contractile reserve can be elicited by stress-ec ho.