BACKGROUND: Cardiogenic shock resulting from acute myocardial infarction is a serious complication with a high mortality rate, but little is known about whether its incidence or outcome has changed over time. As part of an ongoing population-based study of acute myocardial infarction, we examined trends over time in the incidence and mortality rate of cardiogenic shock after acute myocardial infarction. METHODS: We studied 4762 patients with acute myocardial infarction who were admitted to 16 hospitals in the Worcester, Massachusetts, metropolitan area between 1975 and 1988. We determined the incidence of and short-term and long-term mortality due to cardiogenic shock in each of six years during this study period. RESULTS: The incidence of cardiogenic shock complicating acute myocardial infarction remained relatively constant, averaging 7.5 percent. Multivariate regression analysis that controlled for variables affecting incidence revealed significant though inconsistent temporal trends in the incidence of cardiogenic shock. As compared with the risk in 1975, the adjusted relative risk (with 95 percent confidence interval) was 0.83 (0.54 to 1.28) in 1978, 0.96 (0.63 to 1.48) in 1981, 0.68 (0.42 to 1.12) in 1984, 1.16 (0.70 to 1.92) in 1986, and 1.65 (0.99 to 2.77) in 1988. The overall in-hospital mortality rate among patients with cardiogenic shock was significantly higher than that among patients without this complication (77.7 percent vs. 13.5 percent, P less than 0.001). The in-hospital mortality among the patients with shock did not improve between 1975 (73.7 percent) and 1988 (81.7 percent). Long-term survival during the 14-year follow-up period was significantly worse among patients who survived cardiogenic shock during hospitalization than among patients who did not have shock (P less than 0.001). CONCLUSIONS: The results of this observational, community-wide study suggest that neither the incidence nor the prognosis of cardiogenic shock resulting from acute myocardial infarction has improved over time. Both in-hospital and long-term survival remain poor for patients with this complication.