ORBIT-AF: A Bridge to More Sensible Perioperative Anticoagulation

“I’m having thyroid surgery next week. They want to know if you think it is safe for me to stop my Coumadin.”

Physicians treating patients with atrial fibrillation (AF) taking oral anticoagulation (OAC) for stroke prevention are often asked if the OAC can be safely stopped for elective surgery, and whether or not heparin bridging is needed. The answer to the question depends on a careful analysis of the risks and benefits in the individual patient. On one hand, there are patients with mechanical mitral valves who are clearly at high risk when anticoagulation is stopped. For these patients, studies such as BRUISE CONTROL have shown that some procedures, such as pacemaker and defibrillator implantation, are safer when done on uninterrupted warfarin rather than with heparin bridging.¹ Unfortunately, most surgeons expect patients to be off all anticoagulation for most elective procedures.

However, for most patients taking OAC for stroke prevention, whose annual risk of stroke is usually <5%, there is little guidance to help make a decision as to whether heparin bridging should be considered. Unlike warfarin, the newer OACs (NOACs) have a much shorter half-life. Therefore, there is little logic for heparin bridging in these patients. Nonetheless, heparin bridging is still performed perioperatively in some patients taking NOACs. 

The most recent guidelines from the American College of Chest Physicians recommend interruption of oral anticoagulation therapy and the use of bridging therapy with heparin around the time of surgery.² Heparin bridging is common practice; however, it is associated with a significant risk of iatrogenic hemorrhage. In the previous 2006 ACC/AHA/ESC AF Guidelines, there was a statement that made it clear that heparin bridging is not necessary in all patients: “anticoagulation may be interrupted for a period of up to 1 week for surgical or diagnostic procedures that carry a risk of bleeding without substituting heparin, unless they are high-risk patients (particularly those with prior stroke, TIA, or systemic embolism) or when a series of procedures requires interruption of oral anticoagulant therapy for longer periods.”³ There is even less advice on the topic in the more recent 2014 guidelines. In fact, there is only one recommendation in the current AF guidelines related to heparin bridging in patients without mechanical heart valves: “For patients with AF without mechanical heart valves who require interruption of warfarin or new anticoagulants for procedures, decisions about bridging therapy (LMWH or unfractionated heparin) should balance the risks of stroke and bleeding and the duration of time a patient will not be anticoagulated. (Level of Evidence: C).”⁴

The ORBIT-AF registry was recently published.⁵ The study was a prospective, observational registry of 7,372 outpatients with AF that evaluated how common temporary interruptions of OAC were and how often bridging was used. The found that OAC was interrupted in 30% of patients over 2 years, and usually with low-molecular-weight heparin. Bleeding was more common in patients treated with bridging (5.0% vs 1.3%, adjusted OR 3.84, P<.0001), with no reduction in the incidence of stroke. The authors concluded that “Bridging anticoagulation is used in one-quarter of anticoagulation interruptions and is associated with higher risk for bleeding and adverse events. These data do not support the use of routine bridging and additional data are needed to identify best practices around anticoagulation interruptions.”⁵

The ORBIT-AF registry should serve as a reminder that perioperative bridging with heparin has significant risks and should not be used in all patients with AF taking OAC. Perioperative management of anticoagulation cannot be done in a cookbook fashion. Instead, it should involve a careful weighing of the risks and benefits, and recognition that heparin can cause significant harm in the postoperative setting. As more data are collected, it should become clearer which patients should have their OAC interrupted without bridging, which patients should be bridged with heparin, and which procedures are better done on uninterrupted anticoagulation.

References

1. Birnie DH, Healey JS, Wells GA, et al. Pacemaker or defibrillator surgery without interruption of anticoagulation. N Engl J Med. 2013;368(22):2084-2093. Epub 2013 May 9. doi: 10.1056/NEJMoa1302946.
2. Douketis JD, Spyropoulos AC, Spencer FA, et al. Perioperative management of antithrombotic therapy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest. 2012;141(Suppl):e326S-e350S. [Erratum, Chest. 2012;141:1129.]
3. Fuster V, Rydén LE, Cannom DS, et al. ACC/AHA/ESC 2006 Guidelines for the Management of Patients with Atrial Fibrillation: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients With Atrial Fibrillation). J Am Coll Cardiol. 2006;48:e149-246.
4. January C, Wann LS, Alpert JS, et al. 2014 AHA/ACC/HRS Guideline for the Management of Patients With Atrial Fibrillation: Executive Summary: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. Circulation. 2014;130:2071-2104.
5. Steinberg BA, Peterson ED, Kim S, et al. Use and Outcomes Associated with Bridging During Anticoagulation Interruptions in Patients with Atrial Fibrillation: Findings from the Outcomes Registry for Better Informed Treatment of Atrial Fibrillation (ORBIT-AF). Circulation. 2014 Dec 12. [Epub ahead of print] doi: CIRCULATIONAHA.114.011777.