Long-term outcomes of recurrent myocardial infarction: a nationwide Danish study

Background During the past decades outcomes of first-time myocardial infarction (MI) have improved substantially. However, it is unknown if the prognosis following a recurrent MI has also improved similarly. Methods We conducted a nationwide registry-based study including all patients with first-time recurrent MI in Denmark during 2003 to 2022. Cumulative incidences and standardized risk ratios (sRR) of mortality, hospitalization for heart failure (HHF), and subsequent recurrent MI were reported along with stratified analyses by age, sex, and HF status at baseline. Results A total of 24,799 patients with recurrent MI were identified. Between 2003-07 (N=7,368) and 2018-22 (N=4,928), their median age decreased from 75 to 73 years. The prevalence of non-cardiovascular comorbidities increased. The use of lipid-lowering treatment at baseline increased (53.7% to 76.6%), as well as procedures performed in relation to recurrent MI (coronary angiogram, 41.2% to 77.4%; percutaneous coronary intervention, 26.8% to 54.0%). 5-year mortality decreased from 54.1% to 37.3% (sRR: 0.78 [0.74-0.82]), 5-year incidence of HHF decreased from 13.6% to 11.7% (sRR: 0.76 [0.68-0.84]), and 5-year incidence of subsequent recurrent MI decreased from 23.4% to 17.7% (sRR: 0.65 [0.52-0.78]). While mortality and subsequent recurrent MI decreased consistently across subgroups, stratified analyses revealed that the 5-year incidence of HHF increased from 23.9% to 26.2% in patients with previous HF and from 14.3% to 15.9% in males aged ≥75 years. Conclusions Mortality has decreased in parallel with intensified pharmacologic and invasive management of patients with recurrent MI. However, there has been little improvement in heart failure hospitalizations, underscoring that directed preventive strategies are needed to mitigate the heart failure risk in patients with recurrent MI.