EVIDENCE FOR FREE-RADICAL GENERATION AFTER PRIMARY PERCUTANEOUS TRANSLUMINAL CORONARY ANGIOPLASTY RECANALIZATION IN ACUTE MYOCARDIAL-INFARCTION

In animal models, oxygen-derived free radicals have been found to be i mportant mediators of reperfusion injury to ischemic but viable myocar dium. However, in humans, there is no direct evidence of free radical production after the restoration of coronary artery patency in acute m yocardial infarction. The purpose of this study was to quantitate and assess the time course of free radical production in coronary venous o utflow in patients with acute myocardial infarction undergoing success ful recanalization of the infarct-related artery by primary percutaneo us transluminal coronary angioplasty (PTCA). Primary PTCA was performe d in 17 patients with acute myocardial infarction of <6 hours duration . Direct free radical production was assessed by coronary venous efflu ent blood sampling before PTCA and at timed intervals up to 24 hours ( or 48 hours in 6 patients) after recanalization. All samples were arte ry in humans. added to the spin trapping agent alpha-phenyl N-tert but yl nitrone and analyzed by electron paramagnetic resonance spectroscop y. Vessel potency resulted in a sharp increase in free radical signal. Relative to the level before PTCA, the changes reached statistical si gnificance after only 15 minutes (p <0.05). Peak signals were observed between 1 1/2 and 3 1/2 hours (p <0.001), then declined up to 5 hours . A second increase in signal level was detected between 18 and 24 hou rs despite no angiographic evidence of reocclusion. A gradual decline was observed after 24 hours. These findings provide the first direct a nd quantitative evidence of free radical production in the immediate p ostrecanalization phase after thrombotic occlusion of a major coronary artery in humans.