Estimating Risk Of Adverse Cardiac Event after Vascular Surgery Using Currently Available Online Calculators
Danielle A. Moses, MS, PA-C, Lily E. Johnston, MD, Kenneth J. Cherry, MD, John A. Kern, MD, Gilbert R. Upchurch, Jr., MD.
University of Virginia Health System, Charlottesville, VA, USA.
OBJECTIVES: The decision to proceed with vascular surgical interventions requires evaluation of cardiac risk. The study objective was to compare and further validate available online cardiac risk calculators with actual adverse cardiac outcomes at a single institution.
METHODS: All patients from January 2011 through December of 2015 undergoing carotid endarterectomy (CEA), infrainguinal lower extremity bypass, open abdominal aortic aneurysm (AAA) repair, and endovascular abdominal aortic aneurysm repair (EVAR) on the vascular surgical service were included using the Society of Vascular Surgery’s VQI database at our health system. Additional information was collected through retrospective chart review. Each patient was entered through three online risk calculators: 1) The American College of Surgeon’s National Surgical Quality Improvement Program (NSQIP) estimates the risk of cardiac arrest and myocardial infarction (MI); 2) The Revised Cardiac Risk Index (RCRI) estimates risk of MI, pulmonary edema, ventricular fibrillation, primary cardiac arrest, and/or complete heart block; 3) The Vascular Surgery Group of New England’s (VSGNE) Cardiac Risk Index estimates risk of postoperative MI only. Observed adverse cardiac events (ACE) were compared to expected values for each calculator using a Chi-squared goodness of fit test. IRB Exemption was obtained.
RESULTS: 856 cases were included: 350 CEAs, 210 infrainguinal bypases, 77 open AAA repairs, and 219 EVARs. For CEA, no risk calculator showed statistically significant variation from the observed values (NSQIP p=0.45, RCRI p=0.17, VSGNE p=0.24). For infrainguinal bypass, NSQIP slightly under-predicted adverse events (p=0.054), the RCRI strongly under-predicted (p=0.002), and the VSGNE showed no difference (p=0.42).For open AAA repair, NSQIP (p=0.51) and VSGNE (p=0.98) were adequate predictors, but RCRI strongly under-predicted the adverse events (p <0.0001). EVAR cardiac outcomes showed greater adverse events than predicted by all three calculators (NSQIP p=0.02, RCRI p=0.0002, and VSGNE p=0.025). Pooled data for the entire group documented that the VSGNE proved an accurate tool for prediction (p=0.34), while adverse cardiac events were under-predicted by NSQIP (p=0.0055) and RCRI (p <0.001).
CONCLUSIONS: While online cardiac risk calculators of adverse surgical events are easy to reference in broad surgical decision making, there is significant variability in their predictability. Our data suggests that adverse cardiac events often occur at a higher rate than expected; thus creating a platform for future discussion about pre-operative evaluation and post-operative care decision making models.
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