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Hip or knee replacement surgery quadruples heart attack risk

Patients should be blocked from having a hip or knee replacement if they have had a heart attack in the preceding year, as it greatly increases their risk of a second cardiovascular event, concludes a new study.

Danish researchers looked 95,227 patients who underwent total hip or total knee replacements and compared them with matched controls.

Two weeks after hip replacement surgery, patients were 25 times more likely than matched controls to suffer an acute myocardial infarction. The same period after knee surgery, patients were 30 times more likely than matched controls to have a myocardial infarction.

When compared with patients who underwent hernia surgery, hip and knee replacement patients had a significant 21-fold higher risk of acute myocardial infarction (MI) two weeks after surgery.

When extending the analysis to a post-surgery period of six weeks, they found that although patients who had a knee replacement saw their risk of heart attack return to baseline after two weeks, patients who had a hip replacement still demonstrated a fivefold increased risk during the same period, compared with matched controls.

A previous heart attack was associated with a six-week post-operative risk of a recurrent event four times greater than that of matched controls in both groups. This risk decreased as the time between previous MI and surgery increased.

The authors also discovered a strong effect modification by age. In patients who had a hip replacement that were younger than 60 years, there was no significantly increased risk of MI compared with the over-80s, in whom this risk was 25 times greater compared with younger age groups.

The researchers from Utrecht University in the Netherlands concluded: ‘Our data suggests elective total hip replacement surgery should be contraindicated in patients with a previous acute MI in the preceding 12 months before surgery.'

Arch Intern Med 2012, online 23 July


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