Development of a bariatric surgery specific risk assessment tool for perioperative myocardial infarction

Background: Perioperative myocardial infarction (PMI) is a feared complication after surgery. Bariatric surgery, due to its intraabdominal nature, is traditionally considered an intermediate risk procedure. However, there are limited data on MI rates and its predictors in patients undergoing bariatric surgery. Objectives: To enumerate the prevalence of PMI after bariatric surgery and develop a risk assessment tool. Setting: Bariatric surgery centers, United States. Methods: Patients undergoing bariatric surgery were identified from the MBSAQIP participant use file (PUF) 2016. Preoperative characteristics, which correlated with PMI were identified by multivariable regression analysis. PUF 2015 was used to validate the scoring tool developed from PUF 2016. Results: We identified 172,017 patients from PUF 2016. Event rate for MI within 30 days of the operation was .03%; with a mortality rate of 17.3% in patients with a PMI. Four variables correlated with PMI on regression, including history of a previous MI (odds ratio [OR] = 8.57, confidence interval [CI] = 3.4–21.0), preoperative renal insufficiency (OR = 3.83, CI = 1.2–11.4), hyperlipidemia (OR = 2.60, CI = 1.3–5.1), and age >50 (OR = 2.15, CI = 1.1–4.2). Each predicting variable was assigned a score and event rate for MI was assessed with increasing risk score in PUF 2015; the rate increased from 9.5 per 100,000 operations with a score of 0 to 3.2 per 100 with a score of 5. Conclusion: The prevalence of MI after bariatric surgery is lower than other intraabdominal surgeries. However, mortality with PMI is high. This scoring tool can be used by bariatric surgeons to identify patients who will benefit from focused perioperative cardiac workup.