Patients can require warfarin for various diagnoses such as atrial fibrillation, pulmonary embolism, myocardial infarction , stroke and deep venous thrombosis.
As a vit k antagonist, warfarin decreases the coagulation of blood. The anticoagulant effect of warfarin takes 48-72 hours to develop fully,with an estimated duration of action of 2 to 5 days and a reported half life of 2.5 days . Thromboembolic events are known to occur when warfarin is discontinued in the perioperative period.Management of patients receiving long term oral anticoagulants who require dental extraction is based on assessment of risks: the risk of procedure related bleeding if anticoagulants are continued measured against the thromboembolic risks if anticoagulants are stopped.
Thromboembolic events are associated with considerable morbidity and mortality. the risk of thromboembolic events if warfarin is discontinued appears to vary from 0.02 to 1%.
Continuing warfarin during dental surgical procedures will increase the risk of postoperative bleeding requiring intervention. Bleeding complications while inconvenient do not carry the same risks as thromboembolic complication.Most cases of post operative bleeding can be managed by pressure or repacking and suturing the socket.
The activity of warfarin is expressed using international normalised ration (INR).For an individual not taking warfarin a normal coagulation profile is an INR of 1.0
Published trial data suggests that minor dental surgical procedures can be safely carried out on patients with an INR<4. The consensus from reviews on the mannagement of dental patients taking warfarin is that minor dental surgical procedures should be carried out without alteration to patients warfarin therapy if the INR is within the therapeutic range (INR 2.0 to 4.0)
The INR should be measured prior to dental procedures ideally within 24 hrs before the procedure. For patients who have a stable INR, an INR measured within 72 hrs before the procedure is acceptable.Patients presenting with an INR much higher than their normal value , even if it is less than 4.0 should have their procedure postponed and should be referred back to the clinician maintaining their anticoagulant therapy.
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