Impact of preoperative myocardial infarction on surgical outcomes in inpatient orthopaedic surgery

Purpose: The purpose of this study was to evaluate the impact of a preoperative myocardial infarction (MI) on outcomes of inpatient orthopaedic operations. Methods: The National Surgical Quality Improvement Program database was used to identify patients who underwent common orthopaedic operations from 2006 to 2010. Patient demographic data, comorbidities, complications, and lengths of stay were collected. Multivariate logistic regression and linear regression models were used to compare outcomes for patients with and without a history of MI in the six months prior to surgery. Results: Of the 32,462 patients identified, 86 had sustained an MI in the six months prior to surgery. The MI cohort had no cardiac complications but had increased incidences of superficial surgical site infection, unplanned re-intubation, ventilator-assisted respiration for more than 48 hours, pneumonia, sepsis or septic shock, and postoperative mortality within 30 days of surgery, as well as prolonged lengths of stay. Following logistic regression to adjust for baseline differences, a history of MI showed no association with cardiac complications and was significantly associated with superficial surgical site infection (OR 3.6, 95 % CI 1.1-11.8), ventilator dependence for over 48 hours (OR 4.0, 95 % CI 1.1-14.0), and extended length of stay (median with interquartile range 4 [4-4] vs. 5 [5-5] days). Conclusions: A myocardial infarction within six months prior to orthopaedic surgery is not associated with a higher risk of 30-day perioperative cardiac complications; however, it is associated with increased rates of surgical site infection, prolonged ventilator dependence, and longer hospital stay.