High clopidogrel response increases post-off-pump CABG bleeding risk
MedWire News: Patients who have a high level of clopidogrel-induced platelet inhibition are at increased risk for bleeding after off-pump coronary artery bypass graft (OPCABG) surgery, study findings indicate.
This risk persists even when the current clinical protocol of a 5-day delay between clopidogrel discontinuation and surgery date is followed.
It is well known that platelet inhibitory response varies greatly among different patients, the study authors, led by Jae-Kwang Shim from Yonsei University Health System in Seoul, South Korea, write in the Journal of the American College of Cardiology.
They add that their study showed that significantly more patients in the third tertile for platelet inhibitory response to clopidogrel required blood transfusion after OPCABG than those in the first and second tertiles.
In an accompanying editorial Gilles Montalescot (Hôpital Pitié-Salpêtrière, Paris, France) and colleagues commented: "This finding suggests that recommendations of an average delay of discontinuation of antiplatelet therapy before surgery (ie, 5 days for clopidogrel) is not appropriate at the individual level."
Shim and team measured blood loss for the first 24 hours post-surgery and transfusion rates to hospital discharge among 100 patients who received clopidogrel 1 to 5 days before OPCABG.
All patients were arranged in tertiles according to percentage of platelet inhibitory response to clopidogrel, measured by modified thromboelastography.
Patients in the first tertile had a response level range of 15.0%-43.4%, those in the second tertile had a response level of 43.6%-75.9%, and those in the third tertile had a response level of 76.5%-100.0%.
The researchers found that post-OPCABG blood loss increased across tertiles, with a mean blood loss of 623, 682, and 914 ml among patients in the first, second, and third tertiles, respectively (p=0.001).
Multivariate analysis revealed an 11-fold increased risk for blood transfusion among patients in the third tertile, compared with all other tertiles (p=0.001). No other tertiles were associated with an increased bleeding risk, irrespective of clopidogrel discontinuation date.
Furthermore, receiver-operator characteristic curve analysis demonstrated an optimal cutoff platelet inhibitory response level of 70% for predicting increased risk for blood transfusion (p<0.001), with a sensitivity and specificity of 77.8% and 75.0%, respectively.
The researchers conclude: "The findings of the current study might implicate a potential role of modified thromboelastography in deciding the timing of OPCABG in patients who need continued antiplatelet therapy without forfeiting the ischemic benefit."
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By Lauretta Ihonor