The Incremental Risk of Noncardiac Surgery on Adverse Cardiac Events Following Coronary Stenting

BackgroundRecent coronary stent placement and noncardiac surgery contribute to the risk of adverse cardiac events, but the relative contributions of these two factors have not been quantified.ObjectivesThis research was designed to determine the incremental risk of noncardiac surgery on myocardial infarction (MI) and coronary revascularization following coronary stenting.MethodsA U.S. retrospective cohort study of patients receiving coronary stents at Veterans Affairs medical centers between 2000 and 2010 was used to match patients undergoing noncardiac surgery within 24 months of stent placement to two patients with stents not undergoing surgery. Patients were matched on stent type and cardiac risk factors present at the time of stent placement. A composite endpoint of MI and/or cardiac revascularization for the 30-day interval post-surgery was calculated. Adjusted risk differences (RD) were compared across time periods following stent implantation, using generalized estimating equations.ResultsWe matched 20,590 surgical patients to 41,180 nonsurgical patients. During the 30-day interval following noncardiac surgery, the surgical cohort had higher rates of the composite cardiac endpoint (3.1% vs. 1.9%; RD: 1.3%; 95% confidence interval: 1.0% to 1.5%). The incremental risk of noncardiac surgery adjusted for surgical characteristics ranged from 3.5% immediately following stent implantation to 1% at 6 months, after which it remained stable out to 24 months. Factors associated with a significant reduction in risk following surgery more than 6 months post-stent included elective inpatient procedures (ΔRD: 1.8%; p = 0.01), high-risk surgery (ΔRD: 3.7%; p = 0.01), and drug-eluting stent (DES) (ΔRD: 1.3%; p = 0.01).ConclusionsThe incremental risk of noncardiac surgery on adverse cardiac events among post-stent patients is highest in the initial 6 months following stent implantation and stabilizes at 1.0% after 6 months. Elective, high-risk, inpatient surgery, and patients with DES may benefit most from delay from a 6-month delay after stent placement.