Prognostic Impact of In‐Hospital and Postdischarge Heart Failure in Patients With Acute Myocardial Infarction: A Nationwide Analysis Using Data From the Cardiovascular Disease in Norway (CVDNOR) Project

BACKGROUND: Heart failure (HF) is a serious complication of acute myocardial infarction (AMI). We explored the excess mortality associated with HF as an early or late complication of AMI and describe changes over time in such excess mortality. METHODS AND RESULTS: All patients hospitalized with an incident AMI and without history of prior HF hospitalization were followed up to 1 year after AMI discharge for episodes of HF. New HF episodes were classified as in‐hospital HF if diagnosed during the AMI hospitalization or postdischarge HF if diagnosed within 1 year after discharge from the incident AMI. Logistic and Cox regression models were used to explore the excess mortality associated with HF categories. Changes over time in the excess mortality were assessed by testing the interaction between HF status and study year. In‐hospital HF increased in‐hospital mortality 1.79 times (odds ratio [OR], 1.79; 95% CI: 1.68–1.91). The excess mortality associated with HF increased by 4.3 times from 2001 to 2009 (P interaction<0.001) as a consequence of a greater decline of in‐hospital mortality among AMI patients without (9% per year) compared to those with in‐hospital HF (3% per year). Postdischarge HF increased all‐cause and CVD mortality 5.98 times (hazard ratio, 5.98; 95% CI: 5.39–6.64) and 7.93 times (subhazard ratio, 7.93; 95% CI: 6.84 –9.19), respectively. The relative excess 1‐year mortality associated with HF did not change significantly over time. CONCLUSIONS: Development of HF—either as an early or late complication of AMI—has a negative impact on patients' survival. Changes in the excess mortality associated with HF are driven by modest improvements in survival among AMI patients with HF as compared to those without HF.