Medications that prevent the formation of blood clots are commonly called blood thinners. Blood-thinners do not actually thin the blood, but they prevent the blood from clotting. These types of medications are given to people with an increased tendency for thrombosis (blood clot formation) inside blood vessels or to prevent the formation of further clots in those who have had them before. Blood clots that break free can travel through the bloodstream and then lodge in a vessel blocking blood flow. When a blockage occurs in a vessel to the brain, a stroke occurs. Blockage to the heart causes a heart attack. Blood thinners help prevent the serious risk of heart attack and stroke that internal clotting poses.
Since the 1980s, aspirin has been used as a preventive treatment for heart attacks and strokes. Aspirin has an anti-clotting effect and is used in long-term, low doses to prevent heart attacks, strokes and blood clot formation in people at high risk for developing blood clots. The usual dose is one baby aspirin, 81 mg, taken once a day.
For emergency treatment, one full strength aspirin [325 mg] is given during or immediately after a heart attack to reduce the risk of another heart attack or of the death of cardiac tissue. Higher doses are also used after placement of coronary stents and following some cardiac procedures.
Heparin acts by inactivating thrombin and several other clotting factors required for a clot to form. Heparin is used in the hospital intravenously in order to prevent blood clot formation and to enhance the body’s ability to break down existing blood clots. Heparin works immediately at the site used to prevent clotting.
Coumarines (Vitamin K antagonists)
Coumarines are a class of anti-clotting pharmaceuticals prescribed for more than one million Americans each year. Coumarines act by blocking the action of the Vitamin K necessary for the production of prothrombin, which is needed for blood clotting. It takes at least 48 to 72 hours for the anti-clotting effect to develop fully. The most common coumarine medication used is warfarin (also known under the brand names Coumadin, Jantoven, Marevan, and Waran). Generally, warfarin and other coumarin drugs are used to treat patients with atrial fibrillation [the heart’s two upper chambers fibrillate or beat out of normal rhythm], deep venous thrombosis [clotting in the deep leg veins] and pulmonary embolism [blood clots moving into the lungs]. Warfarin is also routinely given to patients who have artificial heart valves.
Warfarin is effective and can decrease the incidence of strokes by 2/3. However, warfarin is cumbersome to use and has numerous drug interactions with other medications. It takes constant monitoring and many patients have inadequate control.
Warfarin can cause serious bleeding. To avoid this, people who take this medication must have routine blood testing to monitor their INR, or International Normalized Ratio. This is an international measure of clotting, which attributes a value of 1.0 to people with a normal ability to clot. As the INR increases, it reflects that a person is less likely to form blood clots. Patients with atrial fibrillation must maintain an INR of 2-3 in order to effectively decrease their risk of stroke.
New anticoagulant medications [blood thinners]
Numerous new anticoagulant medications competing with coumarines have recently come on the market. They have less drug interactions with other medication and are less complicated to monitor. Over time, these new generation of anticoagulants will replace warfarin. They include Pradaxa [generic: dabigatran], Xarelto [generic: rivaroxaban] and Eliquis [generic: apixaban]. Basically, they effect only one of the later non vitamin K clotting factors, whereas, coumarines effects numerous vitamin k factors. Therefore, they have a much shorter clotting effect time than coumarines, so can be stopped for only one day if necessary and do not need constant monitoring.
Dental treatment for patients on blood thinners
Blood thinners do not affect most dental procedures. However, blood thinners can have an effect on blood clotting during dental surgery. Depending on the medication, the dosage and the extent of dental surgery, bleeding can be a concern. The low level of aspirin use for blood thinning is rarely a concern. However, stopping aspirin use the day before dental surgery is usually recommended.
Warfarin use presents the most common potential bleeding problems that dentists encounter. Stopping coumarin medication prior to dental treatment is controversial. Since it takes 48 to 72 hours for warfarin to be effective, it must be stopped 2-3 days before treatment, which puts the patient at risk for serious blood clotting complications. So, the risk-benefit has to be determined, that is, uncontrolled bleeding verses blood clot formation in the vessels.
Warfarin should not be stopped for most dental procedures including most extractions and implant placements. But with any dental surgery, a consultation with the patient’s physician and a recent INR blood test should be reviewed. Usually an INR up to 2.5 is acceptable and safe for dental surgery, thus coumarin does not need to be stopped or lowered. With a common sense approach, I ask my patients if they clot, that is, the bleeding stops, in a reasonable amount of time with direct pressure on a skin cut. During dental surgery, treatment can be done to enhance clotting, such as, the use of clotting agents, stitches, bone grafts and membranes. Bone grafts and membranes preserve bone in an extraction site as well as reduce bleeding.
A number of years ago, I saw a dental phobic 57-year–old patient Todd, who was taking warfarin for deep venous thrombosis from poor circulation in his lower legs and thighs. He was in severe pain from a split lower left molar and needed an extraction. After consulting with his physician and determining his INR was 2.2, Todd continued his normal warfarin regime. With conscious sedation, his tooth was removed, and a bone graft and membrane were placed with no bleeding complications. He was comfortable throughout the procedure with no memory of the event. Eight weeks later, a root replacement titanium implant was placed under conscious sedation with him continuing his warfarin use. Just as during his first treatment, Todd had no bleeding problems and happily had no memory of the implant procedure. 4 months later, an implant crown was fabricated and placed with the same great results.
While a risk-benefit assessment, bleeding verses clotting, must be made for each patient, dentist can perform most dental treatments safely for patients taking warfarin without the need for stopping warfarin therapy.
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George Malkemus has a Family and Cosmetic Dental Practice in Rohnert Park at 2 Padre Parkway, Suite 200. Call 585-8595, or email info@ malkemusdds.com. Visit Dr. Malkemus’ Web site at http://www.malkemusdds.com