Warfarin may reduce stroke in post intracranial hemorrhage

By David Douglas

NEW YORK (Reuters Health) - Warfarin may reduce stroke risk in certain atrial fibrillation (AF) patients with a history of intracranial hemorrhage (ICH), compared to antiplatelet or no antithrombotic therapies, a study suggests.

In a March 11 online paper in Circulation, Dr. Tze-Fan Chao of Taipei Veterans General Hospital and colleagues noted that several non-vitamin K antagonist oral anticoagulants (NOACs) have been shown to be at least as effective as warfarin and much less likely to cause ICH.

However, the situation in patients with a history of ICH, who have been excluded from trials, has been unclear. To investigate, the team examined data on almost 13,000 patients with a history of ICH and a CHA2DS2-VASc score of 2 or more.

In all, 8,211 had no antithrombotic therapy, 3,552 received antiplatelet agents, and 1,154 got warfarin during a mean follow-up of 3.3 years.

The annual ICH rate in warfarin users was 5.9%, with antiplatelet agents it was 5.3%, and with no treatment, 4.2%. The corresponding rates for ischemic stroke were 3.4%, 5.2% and 5.8%.

Thus, although stroke risk was lower in warfarin users, the ICH rate was higher. Therefore, the investigators wrote, "Since the risk of further ICH is high, the risk-benefit ratio with warfarin use for stroke prevention should be carefully weighed for this special AF population."

In fact, Dr. Chao told Reuters Health by email, "Given the high risk of further ICH among AF patients with prior ICH, warfarin should be reserved for patients with a CHA2DS2-VASc score of 6 or more. The use of non-vitamin K antagonist oral anticoagulants may lower the threshold to a CHA2DS2-VASc score to 2 or more, which is similar to that of general AF population."

Antiplatelet therapy, the researchers concluded, should not be used in AF patients with a history of ICH.

Commenting on the findings by email, Dr. Christian T. Ruff, of Brigham and Women's Hospital, Boston, told Reuters Health that this is an important study as it addresses a very difficult-to-manage patient population. "There are very little rigorous data on how to best manage these patients, and this is a large and carefully done analysis."

Dr. Ruff, who conducts research in the field, added that among important points are, "Antiplatelet agents have no role in the care of these patients. Many physicians use aspirin, or other antiplatelet agents, in these patients because they believe it to be safer than warfarin and at least somewhat effective in reducing stroke. These data suggest that antiplatelet agents do not reduce the risk of stroke and cause as much ICH as warfarin."

He also pointed out, "There is a tradeoff in using anticoagulants such as warfarin in these patients. You will significantly decrease their risk of stroke but also increase their risk of ICH. An individualized approach to each patient is necessary. Anticoagulating patients at high risk of stroke (as assessed by common clinic risk scores) makes the most sense."

He concluded, "Limitations of this analysis are that it is an Asian population and may not be generalizable to all populations (Asians have much higher rates of ICH in general than other populations) and we don't have information on the performance of NOACs, a new class of anticoagulants that cause at least 50% less ICH than warfarin."

The National Science Council in Taiwan partially supported this research. One coauthor reported consulting for several companies.

SOURCE: http://bit.ly/1pwW2zM

Circulation 2016.

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