Event Rates and Risk Factors for Recurrent Cardiovascular Events and Mortality in a Contemporary Post Acute Coronary Syndrome Population Representing 239 234 Patients During 2005 to 2018 in the United States

Abstract

Background Patients with acute coronary syndrome (ACS) are recognized by guidelines as remaining at high risk for adverse outcomes. Evidence from contemporary, representative ACS populations in a clinical practice setting is necessary to identify subgroups and strategies for improving patient outcomes. We aimed to describe event rates and risk factors in an ACS population over prolonged follow-up for cardiovascular end points. Methods and Results We identified 239 234 patients in the Optum Research Database (57.2% men; mean [standard deviation] age, 69.2 [12.2] years) with evidence of an ACS hospitalization (index ACS) during January 1, 2005 through December 30, 2018. Subgroups were based on index ACS event (myocardial infarction/unstable angina and revascularization status) and the Thrombolysis In Myocardial Infarction Risk Score for Secondary Prevention. The 5-year event rate for the primary end point representing nonfatal myocardial infarction, nonfatal ischemic stroke, and cardiovascular death was 33.4% (95% CI, 33.1%-33.7%; P<0.001). The risk of experiencing the primary end point was ≈6-fold higher immediately after discharge (≈40.9% annualized risk) as compared with the period 1+ years after hospitalization (≈6.4% annualized risk). Among subgroups, the 5-year primary end point event rate was highest for myocardial infarction without revascularization and a Thrombolysis In Myocardial Infarction Risk Score for Secondary Prevention ≥4, at 47.9% (95% CI, 47.3%-48.4%; P<0.001) and 56.7% (95% CI, 55.9%-57.4%; P<0.001), respectively. Conclusions Patients with ACS remain at very high risk of experiencing recurrent cardiovascular events, particularly early after discharge, with identifiable subgroups at multifold higher risk of specific clinical end points.

Keywords: acute coronary syndrome; cardiovascular events; risk factor; risk stratification.

Figure 1. Consort diagram for patient selection.

Patients with an ACS hospitalization during January 1, 2005 to December 30, 2018 were initially selected. Sequential application of the study inclusion and exclusion criteria resulted in a final study population of N=239 234. ACS indicates acute coronary syndrome; and NDI, National Death Index.

Figure 2. Event rates and instantaneous risk over time for the primary and individual end points.

Shown is the cumulative incidence of the primary end point (first occurrence of nonfatal MI, nonfatal ischemic stroke, or CV death) and individual end points (represented by components of the composite). The KM rates for the primary end point at 1, 3, and 5 years were 14.5% (95% CI, 14.3%–14.6%; P<0.001), 25.2% (95% CI, 25.0%–25.5%; P<0.001), and 33.4% (95% CI, 33.1%–33.7%; P<0.001), respectively. The instantaneous risks (annualized) for the primary end point at 0, 1, and 3 years were 40.9%, 6.7%, and 6.4%, respectively. Below the graphs capturing the cumulative incidence of the primary and individual end points are data on the number of patients at risk of experiencing the corresponding end point. CV indicates cardiovascular; IS, ischemic stroke; KM, Kaplan‐Meier; and MI, myocardial infarction.

Figure 3. Event rates for the primary and individual end points by type of index acute coronary syndrome and use of revascularization.

Shown is the cumulative incidence of the primary end point (first occurrence of nonfatal MI, nonfatal ischemic stroke, or CV death) and individual end points (represented by components of the composite) by index ACS (MI/UA and revascularization status). Below each graph are data on the number of patients in each index ACS subgroup who are at risk of experiencing the corresponding end point. ACS indicates acute coronary syndrome; CV, cardiovascular; IS, ischemic stroke; MI, myocardial infarction; Revasc, revascularization; and UA, unstable angina.

Figure 4. Event rates for the primary and individual end points by categories of TIMI risk score for secondary prevention.

Shown is the cumulative incidence of the primary end point (first occurrence of nonfatal MI, nonfatal ischemic stroke, or CV death) and individual end points (represented by components of the composite) by TRS 2^oP categories. Below each graph are data on the number of patients in each TRS 2^oP category who are at risk of experiencing the corresponding end point. CV indicates cardiovascular; IS, ischemic stroke; MI, myocardial infarction; TIMI, Thrombolysis In Myocardial Infarction; and TRS 2^oP, Thrombolysis in Myocardial Infarction Risk Score for Secondary Prevention.

Figure 5. Event rates for the primary and individual end points by categories of TIMI risk score for secondary prevention and use of revascularization.

Shown is the cumulative incidence of the primary end point (first occurrence of nonfatal MI, nonfatal ischemic stroke, or CV death) and individual end points (represented by components of the composite) by TRS 2^oP categories and use of revascularization. Below each graph are data on the number of patients in each TRS 2^oP category with or without revascularization who are at risk of experiencing the corresponding end point. CV indicates cardiovascular; IS, ischemic stroke; MI, myocardial infarction; Revasc, revascularization; TIMI, Thrombolysis In Myocardial Infarction; and TRS 2^oP, Thrombolysis In Myocardial Infarction Risk Score for Secondary Prevention.