Is vitamin K antagonist (VKA) interruption necessary perioperatively? In a recent presentation, James Douketis, MD, first author of the Perioperative Management of Antithrombotic Therapy guidelines for the American College of Chest Physicians,¹ said warfarin can be safely continued for:

Take-aways In patients who need VKA interruption before surgery, guidelines published by the American College of Chest Physicians recommend stopping VKA about 5 days before surgery. In those patients requiring VKA interruption, the guidelines suggest resuming VKA about 12–24 hours after surgery. In patients with a mechanical heart valve, atrial fibrillation, or venous thromboembolism who are at high risk for thromboembolism, bridging is recommended.

• minor dental procedures
• minor skin procedures
• cataract surgery
• pacemaker or implantable cardioverter-defibrillator placement
• cardiac catheterization ± PCI

To determine whether warfarin interruption is needed, the guidelines recommend thromboembolic risk stratification to determine need for bridging (TABLE).

So, who does require VKA interruption before surgery? The 2012 guidelines have changed the timing for perioperative bridging in several settings. They recommend stopping VKAs 5 days before surgery instead of a shorter time before surgery (Grade 1B). In patients with a mechanical heart valve (MHV), atrial fibrillation (AF), or venous thromboembolism at high risk for thromboembolism, the guidelines suggest bridging anticoagulation instead of no bridging during VKA interruption (Grade 2C); in patients at low risk, the recommendation is for no bridging (Grade 2C).

While minor dental procedures don’t require warfarin discontinuation, what about other dental procedures? The guidelines suggest continuing VKAs with an oral prohemostatic agent or stopping VKAs 2–3 days before the procedure instead of alternative strategies (Grade 2C).

In moderate- to high-risk patients who are receiving acetylsalicylic acid (ASA) and require noncardiac surgery, the guidelines suggest continuing ASA around the time of surgery instead of stopping ASA 7–10 days before surgery (Grade 2C). In patients with a coronary stent who require surgery, the guidelines recommend deferring surgery >6 weeks after BMS placement and >6 months after DES placement instead of undertaking surgery within these time periods (Grade 1C); in patients requiring surgery within 6 weeks of BMS placement or within 6 months of DES placement, the recommendation is to continue antiplatelet therapy perioperatively instead of stopping therapy 7-10 days before surgery (Grade 2C).

Perioperative Bridging

In patients who receive bridging with therapeutic-dose low-molecular weight heparin (LMWH), the guidelines suggest giving the last pre-operative dose about 24 hours before surgery instead of 12 hours before (Grade 2C). For patients being bridged on LMWH and high bleeding risk surgery, the recommendation is to resume therapeutic-dose LMWH 48–72 hours after surgery instead of 23 hours or less after surgery (Grade 2C).

In the TABLE above, notice that in one setting there is evidence for not bridging in patients with a MHV who need surgery. A ‘no bridging’ approach has been studied only in patients with bileaflet mechanical aortic valves.² In this setting no bridging was associated with fewer strokes (0.5%) than LMWH bridging (0.8%) or unfractionated heparin bridging (3.1%). There were lower rates of major bleeding, too, with no bridging (2.4%, 3.7%, and 6.1% respectively). The authors of that study concluded that post-procedural heparin use should be reserved for patients with the highest thromboembolic risk (mitral mechanical heart valve, multiple MHVs, MHV with prior stroke or AF), waiting at least 48 hours before initiating.

What about resuming therapy? For patients who need VKA interruption before surgery, the American College of Chest Physicians suggest resuming VKA about 12–24 hours after surgery instead of later resumption (Grade 2C).

Overall, Dr. Douketis admitted, evidence for bridging is not compelling, but there is a need for more evidence before recommendations can be made to not bridge. Or, to put it another way, bridging anticoagulation is a foggy picture that needs clarifying. A number of randomized clinical trials are ongoing that are assessing bridging versus no bridging strategies.

TABLE: Perioperative Bridging
High Risk (consider bridging)	Moderate Risk (case by case)
Atrial fibrillation recent (<3 months) stroke/TIA CHADS2 5-6 rheumatic heart Mechanical heart valve ball or tilting disc valve mitral valve recent (<6 months) stroke/TIA Venous thromboembolism recent (<3 months) VTE severe thrombophilia	Atrial fibrillation CHADS2 = 3-4 Mechanical heart valve bileaflet aortic valve + risk factors Venous thromboembolism VTE 3-12 months prior or cancer
	Low Risk (consider NOT bridging)
	Atrial fibrillation CHADS2 0-2 Mechanical heart valve bileaflet aortic valve without risks Venous thromboembolism VTE >12 months ago
TIA = transient ischemic attack; VTE = venous thromboembolism Source: Douketis JD, et al. Chest. 2012;141:e326

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References

1. Douketis JD, Spyropoulos AC, Spencer FA, et al.; American College of Chest Physicians. Chest. 2012;141(2 Suppl):e326S-50S.
2. Daniels PR, McBane RD, Litin SC, et al. Thromb Res. 2009;124:300-5.

To listen to an interview with James Douketis, MD, about noncardiac surgeries in prosthetic valve patients, visit youtube.cswnews.org. The interview was conducted by Adolph M. Hutter, Jr., MD.

Keywords: Vitamin K, Stroke, Cardiac Catheterization, Warfarin, Venous Thromboembolism, Defibrillators, Implantable, Stents

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