Natural history of myocardial infarction and angina pectoris in a general population sample of middle-aged men: a 16-year follow-up of the Primary Prevention Study, Göteborg, Sweden

Abstract

Objectives: Although many studies have described prognosis in patients with coronary heart disease (CHD), few have compared outcome in men with clinical evidence of CHD with healthy men from the general population over an extended follow-up. This study aimed to compare long-term prognosis in men with a history of myocardial infarction (MI) and in men with angina pectoris (AP) without MI, with men without clinical signs of CHD.

Design: Longitudinal general population study.

Setting: City of Göteborg, Sweden.

Subjects: From a general population sample, 195 men who had survived an MI for 0-19 years (median 3 years) and 314 men with AP but no MI (uncomplicated AP) at baseline in 1974-77 were identified and compared with 6591 men without clinical coronary disease. All were aged 51-59 years. Incident non-fatal and fatal cases occurring until the beginning of 1983 were also followed (n = 317).

Main outcome measures: Death from CHD, from other causes and from all causes during a follow-up of at least 16 years.

Results: Overall survival was 72% amongst men without coronary disease, 53% amongst men with uncomplicated AP and 34% amongst men with past MI at baseline. In survivors of MI the risk-factor-adjusted relative risk (RR) of coronary death during follow-up was 6.67 (95% confidence interval (CI) 5.29-8.39), of dying from non-cardiovascular causes 1.35 (0.96-1.91), and of dying from any cause 3.20 (2.67-3.83). During the first 4 years after the baseline examination, the adjusted RR of CHD death was 15.96 (10. 29-24.74), and of dying from any cause 5.22 (3.68-7.41). During the last 4 years of follow-up, relative risk was still 5.87 (3.44-10.01) for CHD death and 2.93 (2.05-4.18) for death from any cause. In men with uncomplicated AP, the adjusted relative risk of CHD death during the first 4 years was 4.05 (2.27-7.22) and 3.23 (2.10-4.96) during the last 4-year period. After the first year, the incident MI cases had the same average annual mortality (about 5%) as the prevalent cases.

Conclusions: In survivors of MI, mortality risk remained high even after an extended follow-up. Men with angina had a better prognosis, but still a compromised survival compared with the general population.