Myocardial Infarction as a Risk Factor of Developing Heart Failure - The Tromsø Study

Abstract

Background and aim: 1-2% suffer from heart failure (HF), and the prevalence increases by age. Lifetime risk for HF is highest among men. Myocardial infarction (MI) is a recognized risk factor for HF while HF is associated with increased mortality. The aims for this thesis are to investigate how MI affects the risk of subsequent HF in both genders, in different age groups and whether education has an impact on the risk of HF. Material and method: We followed 26 907 participants >25 years of age attending the Tromsø Study from 1994 to1995 for first ever HF (PPV 88%). Mean observation time was 14.7 years. HF diagnoses were collected from the Discharge Diagnosis Registry of the University Hospital of North Norway. HF occurrence was analyzed for the total population, among genders and in different age groups. Cox proportional hazard regressions were used to estimate hazard ratios (HRs) of developing HF. Main exposure variable was MI. Results: 6.0% of men and 4.4% of women developed HF, a total of 1387 HF diagnoses. Mean age at HF diagnosis was 63.0 years for men, 68.5 years for women. Incidence of HF was highest when aged 66 to 75 years. HR for HF was 2.66 for every 10 years of increased age, and increasing age was a stronger predictor for HF in women. 23.8% men and 10.8% women developed HF subsequent to MI. Multivariable adjusted HR for HF was 3.55 in men and 3.64 in women after MI, but MI was equally associated with HF between genders. Conclusion: We found that the risk of HF subsequent to MI was similar for both genders. The risk of HF increased markedly with age, especially in women. MI´s effect on risk of HF declined with increasing age. Level of education had no effect on risk of HF.