A recent study found that 7.1% of cardioembolic strokes in one institution occurred in individuals withdrawn from warfarin for a medical procedure.  As a cardioembolic mechanism is thought to be responsible for approximately one-fourth of acute ischemic strokes, such cases likely account for 1.5- 2% of all acute ischemic strokes.  These patients often have a large vessel occlusion and poor outcome.

Although provision of parenteral anticoagulant “bridge” treatment to patients withdrawn from an anticoagulant reduces the risk of a cardioembolic stroke, such treatment increases the risk of major postoperative bleeding. Similarly, withdrawal of antiplatelet medication reduces the risk of excessive perioperative bleeding but increases the risk of cerebral or coronary thrombosis.

Medical decision-making in this area must balance the risk of thromboembolism or vascular thrombosis with that of excessive bleeding. Questions that should be considered when determining the best strategy in each individual case include the following:

Which medical and dental procedures require withdrawal of antithrombotic medication?

What is the optimal timing for withdrawal and subsequent resumption of treatment with antithrombotic medication?

To which patients should parenteral anticoagulant “bridge” treatment be provided and for how long should it be continued?

Which parenteral anticoagulant should be used for “bridging,” and how should it be dosed?

What individual patient characteristics are significant in these determinations?

A task group in north Spokane developed these guidelines based on current best evidence to ensure the following:

1. Withdrawal of patients from chronic anticoagulant or antiplatelet medication only when the anticipated medical or dental procedure cannot be performed safely otherwise.
2. Use of parenteral anticoagulant “bridge” treatment only when the risk of perioperative thromboembolism justifies the risk of excessive bleeding.
3. Consistent timing of anticoagulant withdrawal, verification of restoration of coagulation preoperatively, and timing of resumption of warfarin postoperatively.
4. Consistent timing of antiplatelet medication withdrawal and resumption, considering the particular drug being used and individual patient characteristics.
5. Consistent timing and dosing of parenteral anticoagulant “bridge” treatment using low molecular weight heparin or intravenous unfractionated heparin pre- and postoperatively, considering individual patient characteristics.
6. Identification of those patients for whom preoperative insertion of a vena cava filter should be considered.
7. A consistent approach to rapid correction of anticoagulant or antiplatelet treatment for patients who will undergo or have just had urgent surgery.

It should be noted that while these guidelines reflect current best practices, they are empiric and not evidence-based.  They address the most common clinical scenarios that confront physicians. For individual patient characteristics/antithrombotic medication/surgical procedure scenarios not clearly addressed in these guidelines, refer to this publication:

Antithrombotic and Thrombolytic Therapy: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8^th edition).  CHEST 2008: 133:71-968s. http://www.chestjournal.org/content/133/6_suppl

Task Group Members

C. William Britt, Jr., M.D. -  Chair; Medical Director, Stroke Program,                       Providence Holy Family Hospital

Jennifer Taylor, Pharm.D., CACP - Manager, Providence Anticoagulation Clinic

John Ames, D.D.S. - Cascade Oral Surgery

James Valentine, D.D.S. - Oral Surgery Plus

Philip Coff, M.D. - Gastroenterology

Peter Weitzman, M.D. - Medical Director, Providence Anticoagulation Clinic;
Chief Medical Officer, Hospital Specialists, PLLC

John Peterson, M.D. - Spokane Cardiology

With this work the group honors Dr. Leroy Byrd, an outstanding person, physician and benefactor of Providence Holy Family Hospital and many other organizations.

The group acknowledges with much gratitude the contribution of Amy Wilcox, who volunteered many hours of assistance because she shared the passion for improving the care of patients receiving antithrombotic medications in Spokane.