A New Blood Thinner for Patients with Irregular Heart Rhythm

About 250,000 Canadians suffer from irregular heart rhythm called atrial fibrillation (AF). In the U.S. there are approximately 2.3 million adults with AF. Older you are, higher the risk of developing this condition. Some heart problems and medical conditions can put you at a higher risk.

Most dangerous complication of AF is stroke. It accounts for up to 36 percent of all strokes in elderly people. The cost of looking after patients with stroke runs into millions of dollars.

To prevent this, patients with AF are converted to regular (sinus) rhythm by applying direct-current electrical shock (cardioversion), by medications or by ablation therapy. If it is difficult to sustain regular rhythm, then the patients receive blood thinners (like warfarin) on a regular basis to reduce the risk of stroke by 70 percent. Warfarin, as you may know, is a rat poison.

Main advantage of warfarin is that it is cheap and is covered by provincial drug plan. Major disadvantages are that you need frequent blood tests to make sure that the blood concentration of the drug is at a safe level to keep the blood thin but not dangerous enough to make you bleed in the brain or some other place. It is quite difficult to achieve the safe level and maintain it. The blood levels fluctuate when you eat certain kinds of foods or take other medications. So there is always some level of anxiety and uncertainly when you are on warfarin.

Now, here is the good news. In the last few weeks, the Canadian Cardiovascular Society issued new guidelines for prevention of stroke in patients with AF by recommending that patients at high risk of stroke be prescribed the new blood thinner dabigastran (Pradax) instead of warfarin. The new drug has fewer side effects and requires no blood tests. But it is not covered by provincial drug plans.

In a study published in the New England Journal of Medicine (September 17, 2009), the authors report that the rate of major bleeding was 3.36 per cent per year in the warfarin group, as compared with 2.71 per cent per year in the group receiving 110 mg of dabigastran twice a day and 3.11 per cent if you are on 150 mg dabigastran twice a day.

The rate of stroke due to bleeding in the brain was 0.38 per cent per year in the warfarin group, 0.12 per cent in the 110 mg dabigastran group and 0.10 per cent in the 150 mg dabigastran group.

The death rate was 4.13 per cent in the warfarin group, 3.75 per cent in 110 mg dabigastran group and 3.64 per cent per year in 150 mg dabigastran group.

The authors conclude by saying that if you switch over to 110 mg dabigastran twice a day from warfarin then the risk of stroke would be similar to warfarin but lower rate of major bleed.

If you switch over to 150 mg dabigastran twice a day then compared to warfarin, you will have lower risk of stroke but similar risk of major bleed as warfarin.

Dabigastran (Pradax) is made by Boehringer Ingelheim and more information is available on their website: www.boehringer-ingelheim.ca.

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