Declining trend in mortality after myocardial infarction.
All patients under 60 years of age who were discharged from hospital after a first myocardial infarction between 1968 and 1977 in Göteborg were followed for a minimum of 24 months. The patients were unselected, and treatment was standardised. The patients were divided into five two yearly cohorts, and the prognostic comparability and mortality of these cohorts were assessed. There was a reduction in the two year mortality rate after discharge during the 10 year period. Small baseline differences between the cohorts were controlled by multivariate methods, and a subsequent analysis showed that there was a declining trend in mortality between 1968 and 1977. A higher tendency among smokers to give up smoking and a lower prevalence of angina pectoris could explain only part of the reduction in mortality. A small number of patients underwent a coronary bypass operation; the slight increase in the number of operations during the period cannot, however, account for the reduced mortality. Most of the patients in the later cohorts were treated with beta blockers, and this is the most likely explanation for the majority of the decline in mortality.