Changing clinical presentation and outcome of acute myocardial infarction in New Jersey from 1990-2004

Over the past few decades, there has been a dramatic decline in coronary heart disease (CHD) mortality in the face of relatively stable incidence of acute myocardial infarction (AMI). However, the clinical presentation of AMI has been changing with more infarcts classified as subendocardial. Objective To explore closely the change from 1990 to 2004 in the incidence and presentation of hospitalized AMI, its case fatality, and the relationship of these changes to the decline in overall CHD mortality. Design, Setting, and Participants I studied hospitalized AMI cases in New Jersey from 1990-2004 (n=222,944) matched to state death records. The ECG and enzyme presentation of AMI was examined for 1990-1993 and 2001-2004 in 416 patient hospital records. Results CHD mortality declined by 40.8% from 1351 to 799 per 100,000, mostly in persons without an AMI hospitalization in the preceding 4-12 years. However, AMI hospitalization rate was relatively stable. The QMI hospitalization rate declined by approximately 50% in every age group; in contrast, the NQMI hospitalization rate increased 2 to 3 fold in each age group. Crude in-hospital case-fatality decreased from 13.4% in 1990 to 8.8% in 2004 for QMI patients while it increased slightly for NQMI. The 1-year case fatality of QMI decreased from 22.5% in 1990 to 17.8% in 2004 but the 1-year case fatality of NQMI patients increased from 18.3% in 1990 to 23.7% in 2004. Hospital record reviews confirmed a substantial decrease in the frequency of ST elevation and Q wave development in AMI admissions across the study period. A decline in cardiovascular disease (CVD) case-fatality and a marked increase in NCVD case-fatality in four years were observed. The decline in CVD deaths might be attributed by the mix of cases which included milder MIs detected by troponins and possibly more severe cases that underwent revascularization before Q wave develop. One of the contributors to this increasing trend in NCVD deaths might be diabetes, which is known to be associated with higher mortality for both CVD and NCVD. The increasing prevalence of DM may play a significant role in increasing overall deaths, especially among patients following subendocardial infarction. Conclusion Changing clinical presentation of AMI and a worsening prognosis of subendocardial infarction suggest that the pathogenesis of CHD changed significantly during the 15 year study period. The worsening prognosis of subendocardial AMI deserves attention.Ph.D.Includes bibliographical references (p. 72-78)