Effects of Coronary Artery Reperfusion on Myocardial Infarct Size Calculated from Creatine Kinase

Abstract

The effects of coronary artery reperfusion at 1 and 3 h after occlusion on infarct size (IS) in the conscious dog were compared with a second group of dogs that were not reperfused (24 h occlusion). Infarct size was calculated from creatine kinase (CK) appearing in blood samples (IS_s) and myocardial CK depletion (IS_m), and determined from gross and histological inspection of the pathological tissue (IS_p). Under both conditions, IS_m correlated well with IS_p. In dogs with 24-h coronary occlusions, IS_s correlated well with IS_m (IS_s = 14.26 + 1.18 × IS_m, r = 0.92). In reperfused dogs, the relationship remained linear but was altered (IS_s = 15.33 + 2.07 × IS_m, r = 0.89). The slope was significantly greater, P s was compared with IS_p. Moreover, the configuration of the serial blood CK curve was changed significantly by reperfusion. In dogs with a 24-h occlusion, CK rose gradually to a peak at 11.4±0.5 h. In dogs reperfused at 3 h, CK rose sharply at 3 h and reached a peak at 6.8±0.5 h, significantly earlier (P <0.01) than occurred in dogs reperfused at 1 h, i.e., when the peak occurred at 4.2±0.4 h. The rapid appearance of CK in blood after reperfusion at 1 and 3 h suggested a washout phenomena. Thus, reperfusion alters the shape of the serial blood CK curve and results in a different linear relationship between calculated and measured infarct size, resulting in greater recovery of CK in blood per unit of infarcted myocardium.