Hip, Knee Replacement Surgeries Raise Heart Attack Risk

Total hip replacement (THR) and total knee replacement (TKR) surgeries were associated with increased risk of an acute heart attack in the first two weeks after the surgical procedures, according to a new study.

Researchers at Utrecht University (The Netherlands), Aarhus University Hospital (Denmark), and other institutions conducted a retrospective, nationwide cohort study within the Danish national registries, identifying 95,227 patients who underwent a primary THR or TKR surgery from January 1, 1998, through December 31, 2007. The patients were matched to three controls (no THR or TKR) by age, sex, and geographic region. All study participants were followed up for acute myocardial infarct (AMI), and disease- and medication history–adjusted hazard ratios (HRs) were calculated.

The results showed that during the first two postoperative weeks, the risk of AMI was substantially increased in THR patients compared with controls. The risk remained elevated for 2-6 weeks after surgery, and then decreased to baseline levels. For TKR patients, AMI risk was also increased during the first 2 weeks, but did not differ from controls after the first two weeks. The absolute six-week risk of AMI was 0.51% in THR patients and 0.21% in TKR patients. The study was published early online on July 23, 2012, in the Archives of Internal Medicine.

“This study demonstrated an increased risk of AMI during the first two weeks after THR (25-fold) and TKR (31-fold) surgery compared with matched controls,” concluded lead author Arief Lalmohamed, PharmD, of Utrecht University and colleagues. “The risk of AMI sharply decreased after this period, although it remained significantly elevated in the first six weeks for THR patients. The association was strongest in patients 80 years or older, whereas we could not detect a significantly increased risk in patients younger than 60 years.”

In THR or TKR patients, the risk of AMI may be decreased or increased shortly after surgery. On one hand, the surgery itself may result in ischemic complications caused by marrow embolization. On the other hand, antithrombotic agents are commonly used in these patients during hospitalization and have the potential to decrease the risk of AMI.

Related Links:
Utrecht University
Aarhus University Hospital