Higher risk of heart attack with DOACs
People with atrial fibrillation are more prone to myocardial infarction if they’re on direct-acting oral anticoagulants rather than warfarin, a large UK study shows.
Two DOACs, dabigatran and rivaroxaban, more than doubled the risk of MI compared with warfarin in a population of over 30,000 people with an atrial fibrillation diagnosis and follow-up of up to nine years.
The retrospective study adjusted for a range of potential confounders, including sex, BMI, smoking and alcohol, and history of heart or liver disease along with medication to treat these conditions.
The researchers from the University of Southampton and Maastricht University in the Netherlands also found higher MI risks with aspirin compared with warfarin.
Aspirin has been widely used for low-risk patients with atrial fibrillation, although the latest guidelines no longer recommend it.
Related: Spotlight on anticoagulant antidotes
The study, the first to focus on MI risks with DOACs and warfarin, looks set to reignite a debate around the issue, particularly with dabigatran.
The higher risk of MI with dabigatran was first noticed in the original RE-LY trial that led to the drug’s approval. In that trial, dabigatran users had a 38% higher risk of MI than warfarin, although the numbers were too small to be significant.
However, a meta-analysis of RE-LY and six other randomised trials of dabigatran continued to show an increased risk compared with warfarin, with or without the RE-LY data.
The authors of the current study say the differences in MI risk are probably due to the protective effects of warfarin in the pathology of angina pectoris, rather than DOACs actually increasing adding to the risk.
They say the protective effects of warfarin in MI is relatively well known, but the current findings argue strongly against them being a class effect of anticoagulants in general.
“More research should be ongoing as use of direct acting oral anticoagulants increases in the population,” they write in the British Journal of Clinical Pharmacology.
Read the study here.