Aims Heart failure is a serious complication of acute myocardial infarction, leading to a poor prognosis. We explored trends in the risk of heart failure among patients hospitalised with an incident acute myocardial infarction in Norway during 2001-2009. Methods and results A total of 69,372 patients were followed for an episode of heart failure occurring either during (early-onset heart failure) or within one year of discharge from the incident acute myocardial infarction hospitalisation (late-onset heart failure). Logistic regression and competing risk regression models were used to explore trends in early and late-onset heart failure respectively. Overall, 17.1% of patients had early-onset heart failure. The odds of heart failure increased by 2.3% per year (odds ratio = 1.023; 95% confidence interval: 1.015-1.031), influenced by an increase of 5.9% per year among younger (25-69 years) patients while no statistically significant changes occurred among older (70-84 years) patients. Among 47,673 patients discharged alive, without early-onset heart failure, 5.4% experienced late-onset heart failure. The risk of heart failure declined by 6.3% per year (subhazard ratio = 0.937; 95% confidence interval: 0.921-0.954). The decline was statistically significant in both age groups (6.8% per year and 5.9% per year respectively). Overall, the risk of heart failure occurring at any time during the follow up did not change significantly. However, it increased by 3.3% per year in younger patients and declined by 1.5% per year in older patients. Conclusions Heart failure occurring during acute myocardial infarction hospitalisation accounts for the majority of heart failure cases and is characterised by unfavourable trends, while heart failure rates following acute myocardial infarction discharge declined over the study period.
Keywords: Acute myocardial infarction; Cardiovascular Disease in Norway; Norway; heart failure; time trends.