Clopidogrel within 24 hours of surgery increases risk for transfusion, bleeding
MedWire News: Patients receiving clopidogrel within 24 hours before undergoing cardiac surgery are at increased risk for transfusion and hemorrhagic complication, Canadian researchers report in the Annals of Thoracic Surgery.
Their study showed that transfusion and bleeding complication rates were significantly higher if the last dose of clopidogrel was given within 24 hours before surgery than if withdrawn earlier, while the risk for transfusion remained higher if the drug was stopped within 48 hours before surgery.
Indeed, patients who received clopidogrel within 24 hours of surgery had more than a two-fold increased risk for transfusion and around a two-fold increased risk for hemorrhagic complications; those who received the antiplatelet drug within 48 hours had a 1.7-fold increased risk for transfusion.
To better define the relationship between the last dose of clopidogrel before cardiac surgical intervention and bleeding complications, Gregory Hirsch and colleagues from Queen Elizabeth II Health Sciences Center in Halifax, Nova Scotia, examined data for all consecutive patients (n=3779) undergoing isolated coronary artery bypass graft (CABG), isolated valve, or CABG plus valve surgery at their center between June 2004 and August 2008.
Among the 999 patients who were receiving clopidogrel before the operation, the unadjusted in-hospital rate of blood transfusion was considerably higher among those who received clopidogrel within 24 hours before surgery than the overall rate, at 59.9% compared with 34.1%, respectively. Similarly the hemorrhagic complication rate in patients who received clopidogrel within 24 hours was much higher, at 8.0%, than the overall rate of 4.1%.
After adjusting for covariables, clopidogrel administration within 24 hours before surgery was associated with a significant 2.4-fold increased in odds of intraoperative and postoperative blood transfusion (p=0.0001). Clopidogrel within 48 hours of surgery was also associated with a significantly increased risk for transfusion, at an odds ratio of 1.7 (p=0.0271).
Meanwhile treatment with clopidogrel within 24 hours was independently associated with a 2.1-fold increased odds for hemorrhagic complication (tamponade or re-exploration for bleeding; p=0.0042).
The authors conclude: “We recommend that if the clinical situation allows, for patients receiving clopidogrel, undergoing cardiac surgery should be delayed at least 24 hours.
“Also, for cardiac surgery patients, clopidogrel administration should be restricted to those with clear-cut indications for its use. For patients with a high likelihood of surgical intervention, consideration should be given to delaying clopidogrel loading until relevant diagnostic studies can be obtained that will determine the role for urgent cardiac surgical intervention.”
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By Caroline Price