Primary risk factors influence risk of recurrent myocardial infarction/death from coronary heart disease: results from the Stockholm Heart Epidemiology Program (SHEEP).

BACKGROUND: Prognosis after a first myocardial infarction (MI) is influenced by primary risk factors as well as secondary risk factors. There is still a lack of follow-up studies of well-characterized patient cohorts assessing the relative importance of these factors. DESIGN: A cohort of 1635 patients (aged 45-70 years) surviving at least 28 days after a first MI were followed for 6-9 years with regard to recurrent MI/fatal coronary heart disease (CHD). Data were collected through questionnaires, physical examinations, and medical records. METHODS: Hazard ratios (HR) with 95% confidence intervals (CI) for different risk factors were calculated using the Cox proportional hazard model. RESULTS: Of the primary risk factors, diabetes in both sexes was the most important predictor of recurrent MI/fatal CHD, multivariate-adjusted HR in men 1.6 (95% CI; 1.0-2.4) and in women 2.5 (95% CI; 0.9-6.9). Other primary risk factors with prognostic influence were job strain, HR 1.5 (95% CI; 1.0-2.1), and central obesity, HR 1.4 (95% CI; 1.0-2.0), in men and a low level of apolipoprotein A1, HR 2.3 (95% CI; 1.1-5.0), and high-density lipoprotein cholesterol, HR 1.9 (95% CI; 0.9-4.1), in women. The secondary risk factors most detrimental for prognosis were heart failure in men, HR 2.2 (95% CI; 1.2-4.0), and a high peak acute cardiac enzyme level in women, HR 4.4 (95% CI; 2.0-9.7). CONCLUSIONS: Long-term follow-up of patients who survived at least 28 days after a first MI shows that several primary cardiovascular risk factors, particularly diabetes, contribute to the increased risk of recurrent MI/fatal CHD.