Abstract 18554: The Association of Diagnostic Criteria for Myocardial Infarction and Peri-Operative Cardiac Risk Factors in Vascular Surgery Patients

Abstract

Background: The inclusion of cardiac biomarkers and ST-T changes on electrocardiography in the diagnostic criteria for myocardial infarction (MI) has increased the apparent incidence of infarction in the general population. The impact of re-defining MI on the incidence and risk of peri-operative MI is unclear. We evaluate the association between diagnostic criteria changes and incidence of and risk factors for peri-operative MI in vascular surgery patients. Methods: Patients who underwent non-emergent vascular surgery between 2005 and 2011 were identified from the American College of Surgeons’ National Surgical Quality Improvement Program (NSQUIP) multi-center database. In 2005, MI was defined by new Q-waves on electrocardiography. In 2009, the definition included variable electrocardiographic evidence (ST elevation, new left bundle branch block, or new q-waves) or an elevation of cardiac troponin greater than 3 times the upper level of normal. Baseline characteristics were identified, and yearly incidence of MI was determined. Multivariable regression was used to determine risk factors associated with MI according to the old and new definitions. Results: Of 70,811 patients who underwent vascular surgery between 2005 and 2011, 40,017 (57%) were ≥ 70 years old, and 46,206 (65%) were male. High-risk vascular surgery (open abdominal aortic aneurysm repair or aorto-bifemoral bypass) was performed in 7,359 (10%) patients. Peri-operative MI more than tripled from the 2005-2008 to 2009-2011 time periods (1.5% vs. 0.4%; p<0.001). In multivariable analyses, significant risk factors for MI also changed from the earlier to later model (See Table). Conclusions: Re-defining MI increased the apparent incidence of and number of independent risk factors for peri-operative MI. The diagnostic criteria for MI utilized in prior cardiac risk prediction models should be considered when determining risk in patients undergoing non-emergent vascular surgery.