A prior myocardial infarction: how does it affect management and outcomes in recurrent acute coronary syndromes?

Despite improved secondary prevention efforts, acute coronary syndrome (ACS) recurrence among patients with prior history of coronary events remains high. The differences in presentation, management, and subsequent clinical outcomes in patients with and without a prior myocardial infarction (MI) and presenting with another episode of ACS remain unexplored.

A total of 3,624 consecutive patients admitted to the University of Michigan with ACS from January 1999 to June 2006 were studied retrospectively. In-hospital management, outcomes, and postdischarge outcomes such as death, stroke, and reinfarction in patients with and without a prior MI were compared.

Patients with a prior MI were more likely to be older and have a higher incidence of diabetes mellitus, hypertension, hyperlipidemia, and peripheral vascular disease. In-hospital outcomes were not significantly different in the 2 groups, except for a higher incidence of cardiac arrest (4.3% versus 2.5%, p < 0.01) and cardiogenic shock (5.7% versus 3.9%, p = 0.01) among patients without a prior MI. However, at 6 mo postdischarge, the incidences of death (8.0% versus 4.5%, p < 0.0001) and recurrent MI (10.0% versus 5.1%, p < 0.0001) were significantly higher in patients with a prior history of MI compared with those without.

Patients with prior MI with recurrent ACS remain at a higher risk of major adverse events on follow-up. This may be partly explained by the patients not being on optimal medications at presentation, as well as disease progression. Increased efforts must be directed at prevention of recurrent ACS, as well as further risk stratification of these patients to improve their overall outcomes.