HYPERDYNAMIC PERFORMANCE OF REMOTE MYOCARDIUM IN ACUTE INFARCTION - CORRELATION BETWEEN REGIONAL CONTRACTILE FUNCTION AND MYOCARDIAL PERFUSION

During and after myocardial infarction (MI), compensatory contractile and structural changes taking place in the remote uninvolved myocardia l regions have been well described in both experimental and clinical s ettings. However, quantitative information on the changes in perfusion in these legions in relation to their altered contractile function ha ve not been available. This study was designed to assess the in vivo r elationship between contractile function and perfusion in remote uninv olved hyper contractile myocardial regions, subtended by angiographica lly normal coronary arteries in patients with MI and single-vessel cor onary artery disease. We utilized two-dimensional echocardiography and O-15-water positron emission tomography imaging to assess regional co ntractile function and myocardial blood flow, respectively. Measuremen ts were performed in nine patients with single-vessel coronary artery disease and angiographically confirmed recanalization of the infarct-r elated artery, 1-2 days after MI (group A). Only patients demonstratin g severely impaired wall motion of the infarcted area and reactive hyp ercontractility of the remote uninvolved regions were enrolled. Seven patients with previous non-reperfused MI (6-8 months post-MI) served a s a control (group B). Systolic avail thickening and regional myocardi al blood flow data sets were created for the remote myocardial segment s perfused by angiographically detected patent coronary arteries by as signing regions on the tomograms to equivalent echocardiographic segme nts. In the remote regions, wall thickening and regional myocardial bl ood flow were higher in group A patients by 26% (43+/-6% vs 34+/-4%; P =0.005) and 20% (1.06+/-0.15 vs 0.89+/-0.06 ml . g(-1) per minute, P=0 .019), respectively. For both groups of patients, a significant correl ation (r=067; P=0.004) between systolic wall thickening and regional m yocardial blood flow was obtained. Infarcted legions in both groups sh owed no systolic wall thickening. In this selected group of patients t hese data demonstrate: (1) a proportionate increase in contractility a nd regional myocardial blood flow in uninvolved territories in patient s with recent and old MI; (2) the in vivo relationship between contrac tile function and myocardial perfusion in man in these regions. When i nfarcted zones in both groups are equally affected enhanced levels of catecholamines and sympathetic drive as well as different loading cond itions may account for the hyperkinetic performance and consequently f or the increased perfusion level in uninvolved segments in patients wi th recent MI.