ACUTE EPICARDIAL ECG PARAMETERS AS QUANTITATIVE PREDICTORS OF INFARCTSIZE AT 1 WEEK IN THE BABOON

We describe an experimental baboon model that allows quantitative pred iction of myocardial necrosis measured at 1 week from acute epicardial ECG parameters recorded from a high-resolution matrix of fixed epicar dial electrodes, The electrode grid overlies a circumscribed area of u ltimate necrosis, produced by the occlusion of a selected diagonal bra nch of the left anterior descending coronary artery (LAD). This grid a llowed examination of the pattern of changes in ST segment elevation ( ST up arrow) throughout their return to control levels, and profiled c hanges in the distribution of electrodes recording TQ-ST segment defle ctions. Those points more centrally located within the area of ST up a rrow consistently showed greater absolute values of ST up arrow and re mained elevated longer than the more peripheral electrodes. Areas of t he electrode matrix corresponding to those electrode points showing si gnificant ST up arrow (2 mV above control) at each recording interval through 8 hr were fitted to the area of necrosis underlying this elect rode grid. While the maximum area of ST up arrow (maxAst) uniformly ov erestimated infarct size between animals on the order of 25%, regressi on analysis allowed prediction of the extent of infarct from maxAst wi th an error of only 5%. Correlation of maxAst with the epicardial exte nt of infarct, total weight, and volume yielded coefficients of 0.95, 0.85, and 0.91 respectively, while mean ST up arrow (ST up arrow) show ed a poorer correlation with respective coefficients of 0.49, 0.55, an d 0.39, MaxAst proved to be the single best predictor of infarct size assessed at 1 week. (C) 1997 Academic Press.