Comparison of Outcome of Patients With Unstable An ina and Non-Q-Wave Acute Myocardia 9 Infarction With and Without Prior Coronary Artery Bypass Grafting (Throkbolysis in Myocardial lschemia Ill Registry) Neal S. Kleiman, Pierre Theroux, MD, H. Vernon Anderson, MD, William J. Rogers, MD, MD, Bruce Thompson, PhD, and Peter H. Stone, MD, for the TIMI IIIR Investigators The aim of this study was to characterize patients with and without prior coronary artery bypass grafting (CABG) among a prospectively identified cohort of pa- tients presenting with unstable angina or non-G-wave myocardial infarction. Patients in the Thrombolysis in Myocardial Infarction phase III Registry Pros tive Study presented within 96 hours of an episode or unsta- ble an ina or non-Q-wave acute m ocardial infarc- tion. d 2,048 patients, 336 (16.4%) I ad prior CABG. Compared with those without prior CABG, patients were the same age, but were more likely to be men, white, diabetic, have a history of angina or myacar- dial infarction, to have received anti-ischemic medica- tions in the prior week, and to receive intravenous heparin or nitroglycerin, or both, during hospitaliza- tion. They were equally likely to unde o coronary an- giopktsty or CABG. Death or nonfata myocardial in- 7 farction occurred by day 10 in 4.5% of patients with prior CABG and 2.8% of patients without prior CABG (p = 0.11); and by day 42 in 7.7% and 5.1%, respec tively (p = 0.03). The corn infarction, or recurrent ix site of death, myocardial r emia at 1 year was more common among patients with rior CABG (39.3% vs 30.2%, p = 0.002). By multi le or CABG was not indepe n8e %a istic regression, pri- ntly associated with the occurrence of death or myocardial infarction, or the composite of death, myocardial infarction, or recurrent ischemia either at 6 weeks or at 1 year. The likelihood of recurrent ischemic events is greater amo with than without prior CABG, but is most7 patients ikely ex- plained by differences in baseline or treatment char- acteristics which reflect the degree of underfying car- diac disease. (Am J Cardiol 1996;77~227-231) N early 300,000 aortocoronary bypass graft (CABG) procedures are performed yearly in the United States. 1*2 As the population ages, the number of such patients in whom ischemia recurs after surgery is likely to increase. Estimates from the Coronary Artery Surgery Study and Veteran’s Affairs Cooperative Study of Coro- nary Bypass indicate a rate of myocardial infarction of approximately 2% to 3%/year over the first 5 years, with recurrent infarction in as many as 36% of patients at 10 years,3-5 and even higher rates of hospitalization for recurrent ischemia.6 Reports of small series have sug- From Baylor College of Medicine, The Methodist Hospital, Houston, and the University of Texas, Houston, Texas; University of Alabama Medical Center, Birmingham, Alabama; Montrea Heart Institute, Montreal, Canada; Maryland Medical Research Institute, Baltimore, Maryland; and Bri P. ham & Womens’ Hospital, Boston, Massachu- setts. The Thromboysrs m Myocardial Infarction Ill Registry Clinical Centers were supported by Grant ROl -Ht-423 1 1 from the Nation- al Heart, Lung, and Blood Institute, Bethesda, Maryland, and by Grant ROl-Ht-4242.8 from the Data Coordinating Center, Mary land Medical Research Institute, Baltimore, Maryland. Manuscript received lulv 28, 1995: revised manuscriot received and accented -I October 9, 1995. Address for reprints: Data Coordinating Center, ‘Maryland Med ical Research Institute, 600 Wyndhurst Avenue, Baltimore, Maryland 21210. gested a better short-term prognosis after myocardial infarction7 and unstable angina* among patients who have previously undergone CABG, but increased long- term rates of recurrent angina and hospitalization.~* The Thrombolysis in Myocardial Infarction (TIMI) III Reg- istry Prospective Study was a broad-based observation- al study designed to characterize patients with unstable angina or non-Q-wave acute myocardial infarction in 18 clinical units in the USA and Canada. The purpose of this database study was to determine whether there are differences in the baseline characteristics, treatment, and outcome of patients with unstable angina and non-Q- wave acute myocardial infarction based on the presence of CABG before development of the index ischemic syn- drome. METHODS The specific goal of the TIM1 III Registry Prospec- tive Study was to characterize the natural history and response to therapy of patients with unstable angina or non-Q-wave infarction by collecting data from nonran- domized patients in parallel to the ongoing randomized TIM1 IIIA and TIM1 BIB trials9Jo which had narrower inclusion criteria. All patients admitted to participating institutions (see Appendix) who experienced unstable angina, defined as CORONARY ARTERY DISEASE/UNSTABLE ANGINA AFTER BYPASS 227