Colonoscopic Polypectomy in Patients Receiving Anticoagulation Therapy: Some Like It Cold

Abstract

Despite best efforts, medical and surgical interventions have inherent risks, and colonoscopy is no exception. Although colonoscopic complications (such as bleeding) are uncommon among persons with average risk, the chances of them occurring increase when polypectomy is performed, particularly in patients receiving antithrombotic medications. Polypectomy risk may be influenced further by tool selection, removal technique (by fluid injected submucosally beneath the polyp, electrical current, or both), technical proficiency, and periprocedural antithrombotic management decisions. Many professional societies advocate temporary withdrawal of oral anticoagulants and case-by-case decision making regarding heparin bridging (HB) on the basis of a patient s estimated risk for thromboembolic events. A fundamental question for gastroenterologists is whether discontinuation of antithrombotic treatment (with or without HB), which exposes patients to thromboembolic risk, is justifiable for all patients receiving anticoagulants who are undergoing colonoscopy solely on the basis that polypectomy might be performed. Furthermore, HB is cumbersome, and recent evidence suggests that it is not as beneficial as once believed and may actually be harmful. For example, discontinuation of warfarin therapy without HB for elective procedures was shown to be noninferior to HB in preventing thromboembolic events and reducing hemorrhage risk. Heparin bridging also has been linked to a higher rate of postpolypectomy bleeding (odds ratio, 12) (1, 2). Therein lies a quandary for colonoscopists. What is the safest way to remove colon polyps (thus preventing progression to carcinoma) in persons receiving antithrombotic medications? The aforementioned HB data have led physicians to increasingly limit HB to patients at highest risk for thromboembolism and to simply withdraw anticoagulants without HB for all others. However, what if HB is effective in preventing thromboembolism in some patients? Is it fair to expose any patient to thromboembolic risk, regardless of how infrequently thromboembolism might occur? An attractive alternative strategy of continuing antithrombotic therapy without interruption could minimize the incidence of thromboembolic complications while eliminating the need for HB altogether. However, until recently, data on the safety of this strategy in the setting of colonoscopic polypectomy were lacking. Traditionally, colonic polypectomy has been performed with snares (wire lassos that encircle, grasp, and resect polyp tissue) to which an electrical current (heat) is applied, with the notion that electrocoagulation is required to transect tissue, prevent bleeding, and fulgurate microscopic residual polyp that may have escaped resection. These proposed advantages of hot snare polypectomy (HSP) might not be as influential as once believed (3). In fact, concern regarding delayed postpolypectomy bleeding (DPPB) after HSP has driven interest in heat-free techniques that might prevent DPPB and be performed safely without withdrawing oral anticoagulants. A growing body of literature confirms that cold snare polypectomy (CSP), which is snare resection without electrical current, reduces DPPB for polyps with a diameter of 10 mm or less and supports using CSP routinely for these small polyps (4, 5). Recent nonrandomized trials found a very low rate of DPPB (0% in several studies) even for larger polyps (10 to 20 mm) (6). Is CSP safe for patients receiving antithrombotic medications? Can CSP be performed safely without these medications being withdrawn, or must they be discontinued temporarily? Most CSP data come from research in patients not receiving anticoagulants; therefore, these questions remain unanswered. The advent of such techniques as CSP and improvements in endoscopic hemostatic capabilities afford endoscopists opportunities to challenge traditional antithrombotic management paradigms. The study by Takeuchi and colleagues (7) compared bleeding risk attributable to 2 polypectomyanticoagulation combinations: a more traditional strategy of HSP with HB (HB+HSP) versus a novel approach of CSP with continuous administration of oral anticoagulants (CA+CSP). The study found a 7.3% risk reduction in significant postcolonoscopy bleeding after CA+CSP to remove polyps 10 mm and smaller. To our knowledge, this is the first study that directly compares CA+CSP with HB+HSP and adds support to other research suggesting the safety of CSP in patients receiving antithrombotic agents. In one such CSP study, 266 polyps that were 10 mm or smaller were removed from patients receiving antithrombotics (anticoagulant or antiplatelet medication; several agents in some cases); no patients had DPPB. However, prophylactic hemostatic clips were applied to the polypectomy site more often in the group receiving antithrombotics (8). A similar phenomenon occurred in the trial by Takeuchi and colleagues (7): Post-CSP clips were placed prophylactically according to the endoscopist s discretion, without protocol rules governing when clips should be applied. Previous studies of prophylactic clipping of small polypectomy defects failed to demonstrate a reduction in DPPB (9, 10), but its effect in patients who continue antithrombotic therapy remains less clear. Thus, variability in clip application is still a potential confounder of CSP studies and an important question that this study did not address adequately. Aside from DPPB, another concern regarding CSP is that by eliminating electrical current, immediate intraprocedural postpolypectomy bleeding (IPPB) may occur, especially in patients receiving anticoagulants. Intraprocedural postpolypectomy bleeding is a risk factor for incomplete resection (adherent blood obscures remnant polyp tissue, preventing it from being resected). In one recent study, IPPB after CSP occurred much more often in patients receiving antithrombotic medications than in those who were not (9.8% vs. 4.1%, respectively; odds ratio, 2.98) (8). In contrast, Takeuchi and colleagues comparison of HB+HSP and CA+CSP showed no cases of poorly controlled IPPB in either group and similar rates of minor IPPB, findings that may reassure clinicians interested in using CA+CSP. This trial had several other limitations that warrant mention. The lack of blinding introduced opportunities for bias. Furthermore, the study was not powered to fully characterize either class-specific risks for postpolypectomy bleeding in patients using warfarin versus those receiving direct oral anticoagulants or the rate of residual adenoma (incomplete polyp resection), which are important considerations in clinical practice. It also did not compare outcomes of CA with either CSP or HSP with those of simply holding anticoagulation without HB, a strategy commonly used for persons perceived to have a low thromboembolic risk. In summary, this study adds to emerging evidence that small colorectal polyps may be resected safely with CSP while oral anticoagulation continues and provides the first comparative evidence that this strategy may be safer than HB+HSP. The results warrant confirmatory studies, preferably with blinding to the use of anticoagulation and assessment of several additional factors: incomplete polyp resection, the effect of prophylactic hemostatic actions (such as clipping), and the applicability of CA+CSP to removal of larger polyps and to use of other classes of antithrombotic medications (such as thienopyridines).