Knee, hip replacement can heighten heart attack risk, study concludes

Total hip and total knee replacement surgeries may be a boon to patients with osteoarthritis, restoring mobility and greatly reducing pain. But within the first two weeks after the surgical procedures are performed, these patients face a greater risk of heart attack, according to a new study in the Netherlands evaluating data from thousands of Danish patients.

Details are published by Archives of International Medicine, a JAMA Network publication. The finding could lead to increased caution among surgeons before pursuing their implants, which one observer said was a necessary development. It is unclear, however, if regulators would step in to tweak indications or guidelines for either type of implant. (They're already actively scrutinizing metal-on-metal hip replacements, however, due to safety concerns and recalls.) Both procedures are common globally, performed an average 1.8 million times annually, the researchers estimate.

"The present study once again confirms that the perioperative period increases cardiac risks," Arthur Wallace of the University of California, San Francisco, wrote in a statement included with the research announcement. "Physicians must go further than establishing risk factors; physicians must actively work to reduce perioperative risk."

To pursue the project, researchers from Utrecht University and others used Danish national registries that enrolled patients who underwent either total hip replacement or total knee replacement surgery between January 1998 and December 2007 and matched controls. The average age for patients with total hip replacement surgery was just under 72 years, and just over 67 years for patients who underwent total knee replacement.

Researchers found that patients experienced a 25-fold increased risk of acute myocardial infarction during the first two weeks after total hip replacement compared to matched controls. Similarly, researchers tracked a 31-fold increased risk of acute myocardial infarction after total knee replacement. Heart attack risks dropped soon after, but stayed higher for a total of 6 weeks for patients who received the total knee replacement. Patients with the biggest risks were ages 80 and older. But patients younger than 60 years of age escaped that increased danger, the study noted.

As a point of disclosure, the researchers note that the Utrecht Institute for Pharmaceutical Scientists has obtained unrestricted funding for pharmacoepidemiologic research from GlaxoSmithKline ($GSK), the Top Institute Pharma (a private/public entity), the Dutch Medicines Evaluation Board and the Dutch Ministry of Health. The specific study itself was made possible by a grant from the Netherlands Organization for Scientific Research.

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