Effect of β-blocker prescription on the incidence of postoperative myocardial infarction after hip and knee arthroplasty

BACKGROUND: American College of Cardiology/American Heart Association guidelines recommend β-blockade for selected low-and intermediate-risk noncardiac surgery patients. The authors evaluated the effect of perioperative β-blockade on postoperative myocardial infarction (POMI) in low-risk patients undergoing intermediate-risk surgery. METHODS: Patients who underwent elective hip or knee arthroplasty between January 1, 2002 and June 30, 2006 were identified. POMI was defined as a Troponin T value of more than 0.1 ng • ml. Patients were divided into three groups: those prescribed a β-blocker on the day of surgery and throughout their hospital stay (or 7 days, whichever came first), those prescribed a β-blocker on the day of surgery but discontinued during the first 7 days, and those not prescribed a β-blocker on the day of surgery. Propensity analysis and logistic regression were used to determine the independent association of β-blocker exposure on POMI. RESULTS: Of the 5,158 arthroplasty patients, 992 (18%) were treated with β-blockers on the day of surgery. This β-blocker was discontinued in 252 patients (25%). POMI occurred in 77 patients (1.5%). Discontinuation of β-blocker prescription was significantly associated with POMI (odds ratio 2.0; 95% CI 1.1-3.9) and death (odds ratio 2.0; 95% CI 1.0-3.9). CONCLUSION: After adjustment for confounders, discontinuation of β-blocker prescription during the first week after surgery was significantly associated with POMI and death. These findings confirm the American College of Cardiology/American Heart Association Guidelines on Perioperative Cardiovascular Evaluation and Care for Noncardiac Surgery, which recommend not to withdraw β-blocker therapy.