Risk Differences in Secondary Prevention Patients Who Present With Acute Coronary Syndrome and Implications of Guideline-Directed Cholesterol Management

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The 2018 American College of Cardiology/American Heart Association cholesterol guidelines for secondary prevention identified a group of “very high risk” (VHR) patients, those with multiple major atherosclerotic cardiovascular disease (ASCVD) events or 1 major ASCVD event with multiple high-risk features. A second group, “high risk” (HR), was defined as patients without any of the risk features in the VHR group. The incidence and relative risk differences of these 2 groups in a nontrial population has not been well characterized. Using the Northwestern Medicine Enterprise Data Warehouse, we compared the incidence of VHR and HR patients as well as their relative risk for cardiovascular morbidity and mortality in a single-center, large, academic, retrospective cohort study. Total 1,483 patients with acute coronary events from January 2014 to December 2016 were risk stratified into VHR and HR groups. International Classification of Diseases versions 9 and 10 were used to assess for composite events of unstable angina pectoris, non-ST elevation myocardial infarction, or ST-elevation myocardial infarction, ischemic stroke, or all-cause death with a median follow-up of 3.3 years. VHR patients were found to have 87 ± 5.4 composite events per 1,000 patient-years compared with HR patients who had 33 ± 5.1 events per 1,000 patient-years (p <0.001). VHR group had increased risk of future events as compared to the HR group (multivariable adjusted hazard ratio 1.66 [1.01 to 2.74], p = 0.047). In conclusion, these results support the stratification of patients into the VHR and HR risk groups for secondary prevention.

Section snippets

Methods

The Northwestern Medicine Enterprise Data Warehouse (NMEDW) was queried to identify adult patients (age ≥18) who had an ACS event at Northwestern Memorial Hospital between January 1, 2014 and December 31, 2016. In the present study, ACS was defined as a left heart catheterization (LHC) with an associated International Classification of Disease versions 9 and 10 (ICD9/10) diagnosis of unstable angina pectoris, non-ST elevation myocardial infarction, or ST-elevation myocardial infarction. The

Results

Total 1,483 patients with 4,191 PY of follow-up were included (Figure 2). Median follow-up time was 3.3 years. Thirty-five percent of patients were female, 19% were African American, and the average age was 64 ± 13 years. About 1,027 (69%) were VHR and 456 (31%) were HR patients. There were 256 (25%) VHR patients who experienced the composite outcome compared with 41 (9%) of HR patients (p <0.001, Table 1).

The overall composite event incidence rate for our cohort was 61 ± 4.1 per 1,000 PY. In

Discussion

Our data from a large urban academic medical center showed that more than two-thirds (69%) of patients with an ACS event are considered VHR according the new 2018 ACC/AHA Cholesterol Guidelines. Our study is one of the first “real-world” estimates of this number in a US cohort. Although results may vary in different settings, we confirm that VHR patients are at significantly increased risk of developing cardiovascular morbidity and mortality following an ACS event. There were significantly

Author Contribution

Nathan W. Kong: Conceptualization, Methodology, Formal analysis, Data Curation, Writing - Original Draft, Writing - Review & Editing, Visualization Aakash Bavishi: Conceptualization, Methodology, Writing - Review & Editing Ansel Philip Amaral: Conceptualization, Methodology, Writing - Review & Editing Anjan Tibrewala: Conceptualization, Methodology, Writing - Review & Editing Arif Jivan: Conceptualization, Methodology, Writing - Review & Editing Philip Silberman: Software, Investigation, Data

Disclosures

The authors have nothing to disclose.

Acknowledgments

We would like to thank Dr. Scott Grundy, MD, PhD at the University of Texas Southwestern Medical Center for providing feedback on our study. We would also like to recognize Liqi Chen of the Biostatistics Collaboration Center at Northwestern University for her insight and expertise into the statistical analysis of our data.

Data Availability

The datasets generated and used during the current study are available from the corresponding author on reasonable request.

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