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.