NEW YORK (Reuters Health) – Exposure to thienopyridines before cardiac surgery is associated with increased risk of postop stroke, rebleeding and mortality, without any reduction in MI risk, according to the results of a systematic review of the literature on the topic. “Our findings support the current AHA/ACC guidelines to withhold clopidogrel for at least 5 days before elective cardiac surgery,” the Canadian authors comment in their report in the American Journal of Medicine online.They could not reach definite conclusions regarding noncardiac surgery, but add, “We believe it is not unreasonable to extend this caution to patients undergoing elective noncardiac surgery because all of the trends were in the same direction as for the main analysis.” Dr. Finlay A. McAlister and colleagues at the University of Alberta in Edmonton note that increasing numbers of patients are on antiplatelet therapy with clopidogrel or a similar drug. While withholding aspirin before a surgical procedure is associated with an increased risk of ischemic events, they explain, it’s unclear whether maintaining or discontinuing preoperative thienopyridines affects outcomes.To investigate, the researchers identified 37 studies in which patients exposed to a thienopyridine within 5 days before surgery were compared with patients without such exposure — including those who had the drug withheld before surgery as well as those with no previous exposure to a thienopyridine. Only six of the studies involved noncardiac surgery.From the pooled data the authors found that rates of postoperative MI were not significantly different in the two patient groups, at 3.4% in those exposed to thienopyridines in the 5 days before surgery compared to 3.0% among unexposed patients (odds ratio 0.98).However, there were significant differences between the exposed and non-exposed groups in the risk of postop stroke (1.9% vs 1.4%, OR 1.54), re-operation to control bleeding (4.3% vs 1.8%, OR 2.62), and all-cause mortality (3.7% vs 2.6%, OR 1.38), the report indicates. The team explains that 97% of the data in their meta-analysis came from cardiac surgery trials, and there were insufficient data to draw definite conclusions about outcomes of noncardiac surgery.In discussing the results, Dr. McAlister and colleagues note that a 5-day cutoff was used specifically in their analysis in order to test the validity of the AHA/ACC recommendation. “However, as complete recovery of platelet function can take up to 7 days in healthy volunteers,” they point out, “those control patients who stopped thienopyridines between 5 and 7 days before surgery may have still had active metabolites in their systems, thus biasing our results to the null (suggesting that, if anything, we have underestimated the harm arising from thienopyridine exposure).”Reference:

Preoperative Thienopyridine Use and Outcomes after Surgery: A Systematic Review

Am J Med 2012.