Cumulative incidence and risk factors of myocardial infarction during 21 years of follow-up: comparing two cohorts of middle-aged men born 30 years apart

Abstract Background The morbidity and mortality burden associated with coronary artery disease (CAD) has declined over the past decades which are believed to be attributable to reductions in the prevalence of major cardiovascular risk factors alongside with improvements in acute management of myocardial infarction (MI). Nevertheless, CAD remains one of the leading causes of death globally. Recent studies indicated that some major cardiovascular risk factors have been modified over time, with decreasing number of smokers and hypercholesterolemia and increasing rates of obesity and diabetes. This may have impact on the incidence of CAD. Therefore, further understanding of changes of major risk factors for CAD overtime is needed. Aim To study cumulative incidence and predictors of MI in two random general population samples consisting of middle-aged men born 30 years apart. Method The "Study of Men Born In 1913" and the "Study of Men Born In 1943" are two longitudinal cohort studies investigating cardiovascular risk factors and diseases, performed in the same geographic area and using the same methodology, with repeated examinations. Both cohorts were followed prospectively for 21 years from the 50 years of age. MI was defined as new onset of myocardial infarction, fatal or non-fatal. Results A total number of 1625 participants were included in the study. Men born in 1943 had a 34% lower risk of acute MI [HR 0.66 (0.50-0.88), p=0.0051] during follow-up as compared to men born in 1913. Both cohorts had similar risk factors and hypertension was associated with at least 2-fold higher risk for incident MI in men born in 1943 [HR 2.33 (95% CI 1.41 - 3.83)], p=0.0009 as compared to the risk in men born in 1913 [HR: 1.10 (0.74-1.62)]. Conclusion Despite declining incidence of MI the last five decades, risk profile of MI remained almost the same, and hypertension became an increasingly prominent risk factor to MI. Greater efforts should be dedicated in primary prevention in order to further reduce the risk of MI.