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ISSUE of Circulation, Mathey and co- workers report on a large group of patients who had transmural myocardial infarction with early coronary angiography and intracoronary streptokinase.The authors are to be complimented for their skill and for the effort required to maintain emergency angio- graphic teams and facilities.This work adds evidence' that intracoronary throm- bosis is a part of the occlusive coronary process in the early hours of infarction.It confirms that lysis of this thrombus can reestablish angiographically obvious antegrade coronary flow.2This work also supports the recent experience that intracoronary nitroglycerin given in large doses seldom reverses complete cor- onary occlusion,3 contrary to the report of Oliva and Breckinridge.4The size of a myocardial infarction must be deter- mined by the size of the myocardial zone supplied by an occluded coronary artery and by the availability of collateral circulation.It must secondarily be deter- mined by many other factors, delineated by Maroko et al.5 Clinical trials of pharmacologic agents for in- farct reduction are concentrating on these secondary factors.Propranolol,6 7 hyaluronidase,8 steroids9 and glucose, insulin and potassium'0 have been or are be- ing studied.*None of these agents has produced consistent and easily demonstrable myocardial salvage.Other interventions have been designed to reduce the coronary flow deficit.Nitroglycerin has produced mixed results."' 12Calcium antagonists, which affect both coronary flow and myocardial oxygen demand, have not undergone conclusive trials in man.Even attempts to augment collateral flow with the intraaortic balloon pump have not been uniformly successful.'3Acute coronary occlusion with thrombosis produces a distal flow deficit of graded intensity, depending on immediately available collateral circulation.This problem is different from the chronic situation where the significance of collateral circulation has been both challenged and confirmed.14 1 ' The acute problem can *MILIS (Multicenter Investigation of Limitation of Infarct Size).
Leinbach et al. (Sun,) studied this question.