July 23rd, 2012
Elevated Risk for Acute MI After Total-Hip or -Knee Replacement Surgery
A large study reports a high increased risk for acute MI (AMI) in the first 6 weeks after total-hip replacement (THR) or total-knee replacement (TKR) surgery. Analyzing a nationwide cohort from Denmark that included 95,227 patients who underwent THR or TKR and matched controls, Arief Lalmohamed and colleagues calculated the adjusted hazard ratios (HR) for AMI. Their results are published in the Archives of Internal Medicine.
The risk for AMI was significantly higher in the first two postoperative weeks for both THR and TKR, but the risk was higher only in the THR group for weeks 2 through 6.
Adjusted HR, Weeks 1 to 2:
- THR: 25.5 (95% CI, 17.1-37.9)
- TKR: 30.9 (95% CI, 11.1-85.5)
Adjusted HR, Weeks 2 to 6:
- THR: 5.05 (95% CI, 3.58-7.13)
- TKR: 0.81 (95% CI, 0.37-1.77)
At 6 weeks, the absolute rate of AMI was 0.51% in the THR group and 0.21% in the TKR group. The only significant effect modifier identified by the investigators was age, with the greatest excess risk found in patients age 80 or older. By contrast, no increase in risk was found in patients younger than 60 years.
In an accompanying commentary, Arthur Wallace writes that the study “once again confirms that the perioperative period increases cardiac risk. Physicians must go further than establishing risk factors; physicians must actively work to reduce perioperative risk.” Risk can be reduced with the appropriate use of preoperative beta-blockers, clonidine, statins, and aspirin, he writes. Despite level 1 evidence supporting the use of antiischemic agents, many physicians discontinue their use in the perioperative period, he notes.