Continuing Clopidogrel Use Appears Safe in Patients Undergoing Polypectomy

Chicago—A retrospective cohort study of patients taking clopidogrel who underwent elective colonoscopy at the Dallas Veterans Affairs (VA) Medical Center concluded that the cardiovascular risks associated with temporarily discontinuing treatment outweigh the risk of bleeding following polypectomy. Lead investigator Fatema S. Uddin, MD, a gastroenterologist with the University of Texas Southwestern/Dallas VA Medical Center, presented findings at the DDW meeting. She noted the results contradict American Society of Gastrointestinal Endoscopy guidelines recommending discontinuation of antithrombotic agents such as aspirin, warfarin, nonsteroidal anti-inflammatory drugs (NSAIDs), and clopidogrel several days before a high-risk elective endoscopic procedure. Dr. Uddin said approximately three quarters of Americans >60 years of age have cardiovascular disease and 20% require antithrombotic agents.

Stopping these medications can result in morbidity or death from myocardial infarction, cerebrovascular accidents, or thrombotic events. Specifically, discontinuing clopidogrel increases the risk of myocardial infarction, cerebrovascular events, and stent thrombosis. According to Dr. Uddin, stopping both aspirin and clopidogrel leads to the greatest risk of stent thrombosis. If both are discontinued, the median time to event is 7 days. In 6% of cases in which patients discontinued clopidogrel but continued taking aspirin, stent thrombosis occurred within 10 days of stopping clopidogrel. “This is relevant to us, because we would typically ask for clopidogrel to be held for 7 to 10 days prior to colonoscopy and, if polypectomy is performed, may elect to continue to hold that medication for an additional 5 to 7 days afterwards,” Dr. Uddin explained. The investigative team reviewed records for patients undergoing colonoscopy with polypectomy at the Dallas VA between July 2008 and December 2009.

After excluding patients taking warfarin, they identified a cohort of 118 clopidogrel users (median age, 64.9 years) who continued therapy and a control group of 1849 nonusers (median age, 62.4 years). Baseline characteristics differed greatly between the groups, with significantly higher rates of coronary artery disease, chronic kidney disease, and lung disease in the clopidogrel arm. Clopidogrel users were also significantly more likely to take concurrent aspirin, whereas significantly more control patients took NSAIDs. In the clopidogrel arm, 360 polypectomies were performed compared with 5671 in the control group. Patients in each group had a median of 3.1 polyps removed, most of which were <1 cm. Hemoclips were used significantly more often in clopidogrel patients (P=.0001). In the clopidogrel arm, only 1 patient—also an aspirin user—developed bleeding, which occurred 8 days after polypectomy of 7 polyps; no transfusion was needed. The bleeding rate postpolypectomy was 0.8% in the clopidogrel arm and 0.3% in the control arm, a difference that was not significant (P=.37). Due to variation in baseline characteristics between the cohorts, particularly in prevalence of diseases that increase bleeding risk, the researchers matched up 111 patients from each group for a propensity analysis.

Results were similar to the overall findings, with a 0.9% bleeding rate in the clopidogrel group and no bleeding events in the control group, which was not statistically significant (P=.99). Dr. Uddin said aside from the inherent limitations of a retrospective study, because most patients had polyps <1 cm, the findings have limited applicability to individuals with larger polyps. The more frequent use of hemoclips among clopidogrel patients might also have confounded the results. “We speculate that the cardiovascular risk of routinely discontinuing clopidogrel may well exceed any risk of postpolypectomy bleeding,” Dr. Uddin concluded. The researchers are currently conducting a prospective study to clarify the issue.