Aspirin Doubles Heart Attack Risk in Patients with Atrial Fibrillation

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aspirinIf you’re taking an aspirin a day in the hopes it will reduce your risk of a heart attack or stroke, a new study indicates your strategy may backfire. The study found that people with abnormal heart rhythm who take aspirin daily have nearly double the risk of having a heart attack compared to people who take the blood thinner drug warfarin.

Ironically, many people chose to take aspirin over the anticoagulant drug warfarin (Coumadin®), since warfarin has many serious side effects such as severe bleeding or bleeding from the gums, intense headaches, stomach and joint pain, and vomiting blood.  Aspirin was thought to be safer.

In the study, researchers from Southampton University in the United Kingdom and Maastricht University in the Netherlands examined prescription history and health records and heart problems in 30,000 patients with atrial fibrillation, a condition that leads to an irregular and often rapid heart rate. Of those subjects, 15,400 used aspirin, 13,098 used a class of drugs known as vitamin K antagonists such as warfarin, 1,266 took a new class of drugs known as direct oral anticoagulants (DOACs), and 382 were treated with a mixture of different agents. Researchers followed the subjects taking DOACs for a year and people taking the vitamin K antagonists and aspirin for three years.

The study, published in the British Journal of Clinical Pharmacology, found that people who took aspirin were at higher risk of having a heart attack compared to the patients treated with other drugs. Patients treated with aspirin were 1.9 times more likely to have an acute heart attack compared to those subjects on warfarin.

According to lead study author Leo Stolk from Maastricht University, “Oral anticoagulant treatment with vitamin K antagonists (VKAs) has been the cornerstone for the prevention of stroke in patients with atrial fibrillation for decades. We identified an … increased risk of [heart attacks] among current and past aspirin users in comparison with VKAs. There also exists doubt about the usefulness of aspirin in atrial fibrillation. In new guidelines aspirin is no longer included.”

The study also found similar risks with the DOAC drugs. This new class of drugs doubled the risk of a heart attack.

The results support new guidance statements that warn against aspirin use by patients with atrial fibrillation.

These recommendations have changed from the past, when general practitioners and heart specialists prescribed aspirin as a matter of practice since it was thought to thin the blood and prevent blood clots responsible for strokes. However, newer evidence indicates aspirin may cause bleeding in the stomach and in some cases bleeding in the brain that can result in a stroke.

Source: Stolk LM, de Vries F, Ebbelaar C, de Boer A, Schalekamp T, Souverein P, Ten Cate-Hoek A, Burden AM. Risk of myocardial infarction in patients with atrial fibrillation using vitamin K antagonists, aspirin or direct acting oral anticoagulants. Br J Clin Pharmacol. March 22, 2017. doi: 10.1111/bcp.13264.