There is increasing use of warfarin and antiplatelet agents in the aging population for various indications. These patients are often referred for endoscopy for investigation of abdominal pain, dyspepsia, change of bowel habit, family history of bowel cancer, positive faecal occult blood, anaemia, polyp surveillance etc.
There is also clear data from the CAPRIE (1) and the CURE (2) trials of increased incidence of gastrointestinal bleeding from the use of Clopidogrel and Aspirin. Some of these patients present for endoscopy with anaemia and some with frank bleeding. The pivotal question then is how do we manage antithrombotic agents (ATA) in the periendoscopic period without increasing risk of thromboemblism and without increasing risk of bleeding from the endoscopic procedure itself? Let us examine the evidence.
Determination of what we do with antithrombotic therapy (ATA) prior to gastrointestinal endoscopy must stem from correct assessment of patient’s thromboembolic risk and inherent risk of the procedure itself. Tables 1 and 2 categorize these risks for the patient and for the procedure respectively.
Patient’s Thromboembolic risk
Deep vein thrombosis.
Thromboembolic event in last 6 months.
Valvular heart disease with prior thromboembolism.
Endoscopic bleeding risk
Thromboembolic risk: Risk of thromboembolism, in low risk patients (with uncomplicated AF, no previous strokes, bioprosthetic heart valves, bare metal coronary stents a year after insertion etc.,) who interrupt warfarin for 4-7 days without bridging with low molecular weight heparin (LMWH), is low(1-2per 1000 patients). Risk, however, is higher (3%) in elderly patients with AF specially women, patients with prior strokes, poor left ventricular function, hyperlipidaemia, hypertension, family history of vascular disease, mechanical mitral valve etc. Recent study(3) indicate low (0.5%) risk of thromboembolism in low to intermediate risk patients who interrupt warfarin, without bridging with LMWH, for colonoscopy.
Risk of procedure related haemorrhage: Table 2 refers to low and high risk endoscopy procedures. With normal haemostasis, bleeding risk for high risk procedures is 5% for laser photocoagulation, 4% for gastric polypectomy, 2.5% for sphincterotomy, 0.4-3.4% for colonoscopic polypectomy and removal of ≥ 1cm polyps. Even bridging therapy with LMWH can be associated with increased risk of bleeding.
Risk reduction in the periendoscopic period: It is apparent from the above discussion that the risk of thromboembolism and the risk of procedure determines what one does with antithrombotic agents (ATA) of the patient. I practise the following:
- I treat most endoscopic procedures as potentially high risk given that, in most cases, one can not predict whether polyps would be found ,whether angioectasia would need to be coagulated or whether a stricture would need to be dilated until you are in the midst of the procedure. Therefore, I either stop ATA for low risk patients or bridge with LMWH for high risk patients.
- For low risk patients, I stop Clopidogrel 8-9 days before or Warfarin 6 days prior to procedure and recommence as soon as safe after the procedure depending on whether polypectomy etc., has been performed.
- For high risk patients, I bridge withdrawal of ATA with LMWH discontinuing LMWH 24 hours prior to procedure as per recommendation of some expert haematologists.
- I recommence Clopidogrel or Warfarin as soon as safe after the procedure, depending on polypectomy etc., in high risk patients, with or without LMWH bridge for a few more days.
- After removal of large polyps, I delay reintroduction of Clopidogrel or Warfarin for 2-3 days while continuing LMWH in the high risk patient in the interim.
- In the high risk patient, the concept of a diagnostic colonoscopy one day, while continuing ATA, followed by a therapeutic colonoscopy on another day (after managing ATA) depending on whether polyps/angioectasia etc. were found in the first colonoscopy, is often rejected by the patients given the arduous nature of bowel preparations.
- Issues regarding risk of coronary stent occlusion off Clopidogrel is complex. Experts maintain that risk of stent occlusion drops substantially after the first 3 months on dual antiplatelet treatment. For bare metal stents in place for a year, Clopidogrel probably can be discontinued for 7-10 days for the endoscopy to take place. For drug eluting stents, the suggestion is to continue Clopidogrel indefinitely! I defer these issues to patient’s cardiologist.
- Although aspirin and NSAIDs are considered low risk for endoscopic procedures, where large polyps are removed, aspirin can be an issue in post polypectomy bleeding. I prefer to discontinue aspirin for 5 days prior to colonoscopies.
- Above discussion outlines the issues in general with regard to ATA. Management of ATA (Clopidogrel and Warfarin), prior to endoscopy, needs to be individualised and hence recommend a prior consultation with the endoscopist.References:
1.CAPRIE steering committee:Lancet,1996;348:1329-39.
2.Clopidogrel….N Engl J Med 2001;345:494-502.
3.Garcia DA et al Arch Intern Med.2008;168:63-9.
Further reading: Abraham NS: Anticoagulation and antiplatelet management: Syllabus: Endoscopic practice 2008,ASGE,131-136.