Pathophysiology and Natural History Coronary Artery Disease

The relationships among clinical variables, coronary anatomy, and left ventricular function during the early hours of acute myocardial infarction (AMI) were evaluated from data acquired in the Western Washington Intracoronary Streptokinase Trial. All patients had symptoms and electrocardiographic changes typical of AMI. All data were obtained before treatment with streptokinase. Mean time to catheterization was 4.1 hr after onset of symptoms. Coronary angiograms (n = 245) were analyzed for location of infarct-related occlusion and collateral flow to the infarct bed. Left ventricular ejection fraction and regional left ventricular function were quantitated in 227. Sixty-two percent of occlusions were in the most proximal segment of the involved coronary artery. Collateral circulation was seen in 42% overall, in 31% with left anterior descending artery (LAD) occlusion, and in 52% with right coronary artery (RCA) occlusion (p < .005). Left ventricular ejection fraction was lowest and regional function was most abnormal in the group with proximal LAD occlusion. Hyperkinesis was present in 32%; in those with hyperkinesis, hyperkinetic segment length was longest in those with RCA or circumflex occlusion. Multivariate analysis identified proximal LAD occlusion as the factor most closely associated with left ventricular ejection fraction and with measures of left ventricular regional hypofunction. We conclude that (1) AMI is usually caused by occlusion or subtotal occlusion in the most proximal portion of the involved coronary artery, (2) collateral circulation is more frequent with RCA than with LAD occlusion, and (3) location of the infarct-related occlusion is the most important determinant of global and regional left ventricular function in the early hours of AMI. Circulation 72, No. 2, 292-301, 1985. THERAPY of acute myocardial infarction (AMI) has undergone a series of revolutionary changes in the past 12 years. With the realization that cardiac catheterization can be performed in the early hours of the acute event with minimal additional risk,' 2 aggressive therapies for the treatment of AMI have evolved. Emergency coronary artery bypass surgery,3" 4 intracoronary infusion of thrombolytic agents,' I-' and percutaneous From the Department of Medicine, Division of Cardiology, and the Department of Biostatistics, University of Washington School of Medicine, and the Seattle Veterans Administration Medical Center, Seattle. Supported irn part by the W. M. Keck Foundation and the Medical Research Service of the Veterans Administration. Dr. Stadius was supported in part by a research fellowship from the Washington Affiliate of the American Heart Association. Address for correspondence: J. Ward Kennedy, M.D., Division of Cardiology, RG-22, University Hospital, Seattle, WA 98195. Received April 3, 1985; accepted May 9, 1985. *Principal investigators and their associates are listed in an appendix to this article. transluminal coronary angioplasty't 9 are all being used in attempts to improve mortality after AMI. Each of these therapies is dependent on knowledge of coronary artery anatomy. Despite the recent widespread use of these different therapies, systematic description of coronary anatomic findings during the early hours of AMI has not yet been reported. Furthermore, the relationships among baseline clinical characteristics, left ventricular function, and coronary anatomy has not been widely studied in man. Our objective in this report was to describe the angiographic findings in patients in the Western Washington Intracoronary Streptokinase Trials, to define coronary anatomy and global and regional left ventricular function, and to study the relationships among coronary anatomy, left ventricular function, and clinical features of these patients. CIRCULATION 292 by gest on A ril 7, 2017 http://ciajournals.org/ D ow nladed from PATHOPHYSIOLOGY AND NATURAL HISTORY-CORONARY ARTERY DISEASE