Hospital Mortality in Acute Myocardial Infarction in the Era of Reperfusion Therapy (the Myocardial Infarction Triage and Intervention Project) Charles Maynard, PhD, W. Douglas Weaver, MD, Paul E. Litwin, MS, Jenny S. Martin, RN, Peter J. Kudenchuk, MD, Timothy A. Dewhurst, MD, Mickey S. Eisenberg, MD, PhD, Alfred P. Hallstrom, PhD, and Joseph Chambers, MD, for the MIT1 Project Investigators This study was conducted in 19 hospitals in the metropolitan Seattle area and included 6,270 UR selected patients who had acute myocardial infarction (AMI) between January 1966 and April 1991. Hospital mortality was determined and re- lated to patient demographic and clinical charao teristics, the use of reperfusion therapies, and to complications after AMI. Thrombolytic therapy or direct coronary angioplasty <6 hours from symp tom onset was used to treat 1,165 (19%) and 524 (9%) patients, respectively. There were 629 (10%) hospital deaths; most occurred during the first 3 days of hospitalization. Factors affecting mortali- ty after admission included: recurrent chest pain, recurrent AMI, development of heart failure, and the occurrence of stroke. After adjustment for age, treatment with thrombolytic therapy or direct angioplasty had no independent effect on reduc- ing the overall mortality rate. Hospital mortality rates for AMI have improved considerably since 1970, although recurrent myocardial ischemic events continue to have an adverse effect on out- come. The current use of reperfusion treatments has had minimal causal impact on overall mortali- ty rates, principally because less than one third of patients, who are relatively “low risk,” are es@- ble and receive these treatments. (Am J Cardiol1993;72:877-662) From the Department of Medicine, School of Medicine, and the De- partment of Biostatistics, School of Public Health and Community Medicine, University of Washington, Seattle, Washington. This study was supported by Grant ROl HL38454 from the National Heart, Lung, and Blood Institute, Bethesda, Maryland, and by an unrestricted grant from Genentech, Inc., South San Francisco, California. Manuscript received March 16, 1993; revised manuscript received and accepted June 2, 1993. Address for reprints: Charles Maynard, PhD, MIT1 Project HL-21, 1910 Fait-view East, #205, Seattle, Washington 98102. S ince 1970, the number of patients hospitalized for acute myocardial infarction (AMI) in the United States has steadily increased, yet case fatality rates have steadily declined.’ In previous studies of in-hospi- tal mortality for AMI, age, sex, evidence of prior car- diac illness, typeof infarct (Q-wave vs non-Q-wave), and the location and size of the infarct as well as resul- tant leftventricular function, each have been identified as important predictors of hospital mortality.2-4 In the past decade, aspirin and thrombolytic therapy have each been shown to be effective in reducing mortality in patients considered appropriate for treatment with these drugs.5 Other means of coronary reperfusion, including direct coronary angioplasty, rescue angioplasty of failed thrombolytic drug treatment, and coronary artery bypass surgery have also been evaluated.6,7 Since these re- perfusion therapies may prevent damage to jeopardized myocardium,it is importantthat serious silent and symp- tomatic (recurrent angina) myocardial ischemia be de- tected during the course of hospitahzation.4,8 This study examines, in the era of reperfusion therapy, factors affecting hospital mortality, when death occurred, and the event immediately preceding death. METHODS Patient population: From January 1988 through April 1991, 6,270 patients with AMI were admitted to 19 hospitals in King County, Washington, which in- cludes the city of Seattle. The hospital records for each consecutive patient were reviewed,and relevant infor- mation was recordedon study data forms and entered in the Myocardial Infarction Triage and Intervention (MITI) database. The details of this project as well as the scope of the database have been described.9 This population-based study contains all patients who had contirmation of AMI at discharge or death as indicated by coronarycare unitlogs and review of dis- charge diagnoses from medical records. The small num- bers of patients with AMI complicated by cardiac arrest and resuscitation before hospital admission were exclud- ed as were patients who developed AMI after admission for treatmentof another medical problem (e.g., subse- quent to noncardiacsurgery). Duringthis 3-year study, 94% of patients had 1 hospital admission for AMI, 5% had 2 admissions, and 1% had 23 admissions for AMI. Study variables: Demographic and diagnostic vari- ables were collected and includedage, sex, race, mode ACUTE MYOCARDIAL INFARCTION MORTALITY 877