Limitation of experimental infarct size by drugs.

Testing drugs on their efficacy in limiting infarct size is difficult in the experimental setting because of the considerable variation in the sizes of infarcts produced in control animals, mainly in dogs. This variation in infarct size in the canine model is theoretically related to variations in the size of the ischemic bed or area at risk, in pre-existing collateral blood flow, and in myocardial metabolic demand. In this study, we identified the determinants of infarct size after different periods of coronary artery occlusion in unconscious dogs and constructed a mathematical model based on these determinants using stepwise logistic regression analysis. Eighty-nine percent of the variability in infarct size is accounted for by variations in the size of the ischemic bed and coronary collateral blood flow. Using this model, we were able to predict infarct size and to make valid comparisons between treated and control groups.