Usefulness of the Myocardial Infarction and Cardiac Arrest Calculator as a Discriminator of Adverse Cardiac Events After Elective Hip and Knee Surgery

Abstract

The 2014 American College of Cardiology and American Heart Association guidelines on perioperative evaluation recommend differentiating patients at low risk (<1%) versus elevated risk (≥1%) for cardiac complications to guide appropriate preoperative testing. Among the tools recommended for estimating perioperative risk is the National Surgical Quality Improvement Program (NSQIP) Myocardial Infarction and Cardiac Arrest (MICA) risk calculator. We investigated whether the NSQIP MICA risk calculator would accurately discriminate adverse cardiac events in a cohort of adult patients undergoing elective orthopedic surgery. We retrospectively reviewed 1,098 consecutive, elective orthopedic surgeries performed at Hershey Medical Center from January 1, 2013, to December 31, 2014. Adverse cardiac events were defined as myocardial infarction or cardiac arrest within 30 days of surgery. The mean estimated risk for adverse cardiac events using the NSQIP MICA risk calculator was 0.54%, which was not significantly different (p = 1) compared with the observed incidence of 0.64% (7 of 1,098 procedures). The c-statistic for discriminating adverse cardiac events was 0.85 (95% CI 0.67 to 1) for the NSQIP MICA risk calculator and 0.9 (95% CI 0.75 to 1) for the Revised Cardiac Risk Index. In conclusion, the NSQIP MICA risk calculator is a good discriminator of adverse cardiac events in patients undergoing elective hip and knee surgery, performing comparably to the Revised Cardiac Risk Index.