Temporal Trends in the Prevalence, Characteristics, Treatment, and Clinical Outcomes of Patients with Prior Myocardial Infarction who are Admitted with an Acute Coronary Syndrome

Background: Patients with prior myocardial infarction (MI) are at increased risk for recurrent cardiovascular events. Advances in treatment in the last decade has improved prognosis of patients with acute coronary syndrome (ACS), yet it is not known whether similar trends exist in patients with prior MI, a particularly high-risk group.

Methods: Study cohort was derived from the ACS Israeli Survey (ACSIS) which was divided to early (2000-2008) and late (2010-2016) time-periods and prior MI status. Clinical outcomes included 30-d MACE (death, MI, stroke, unstable angina, stent thrombosis, urgent revascularization) and 1-year mortality.

Results: A total of 15,211 patients were included, of whom 4627(30%) had a prior MI. These patients were older (67y vs 63y), more commonly male, had more prior comorbidities, and a higher proportion had a GRACE score>140 (38.4% vs 12.2%). Patients with prior MI received more prior medications such as aspirin, statins, antihypertensives and hypoglycemics. Over time, utilization of guideline-recommended therapies such as P2Y12 inhibitors, statins, and PCI has significantly improved in patients with prior MI. However, compared with patients without prior MI, they were still treated less commonly by PCI (61% vs. 74%). Overall, patients with prior MI had a higher 30-d MACE (13.7% vs 17.2%, p<0.001) and 1-year mortality (8.2% vs. 13.1%, p<0.001). Although in the late period, 30-d MACE nearly halved (22.7% vs. 11.8%) and 1-year mortality also decreased (15.5% vs. 10.7%) for these patients. After adjustment, prior MI was independently associated with 1-year mortality (HR 1.13, 95% CI 1.01-1.26, p=0.04) and the late time-period was associated with reduced 1-year mortality (HR 0.75, 95% CI 0.65-0.84, p<0.001).

Conclusion: Patients with prior MI have a worse prognosis after ACS despite being treated with prior medications and improvement in guideline-based therapies. Although still undertreated, their clinical outcome has significantly improved throughout the years.