Can an Aspirin a Day Keep Post-Atrial Fibrillation Clots Away?

Roughly 50 million Americans take daily low-dose aspirin for cardioprevention, as it is generally perceived as a safe, effective, and inexpensive OTC preventive medication for cardiovascular disease. For patients who have nonvalvular atrial fibrillation (AF), many guidelines recommend aspirin as thromboprophylaxis among those who are not considered to be high risk.

In this context, aspirin represents an “easy” or “soft” anticoagulation option. However, a new article published ahead of print in the European Heart Journal joins a growing chorus of voices suggesting that aspirin may be overused.

Written by cardiac academics from the University of Sydney in Australia, the opinion piece reviewed aspirin’s long history in cardiac prevention. The medication’s initial use grew from the results of the 1989 Physicians Health Study, which showed that aspirin reduced the risk of non-fatal myocardial infarction. However, many do not realize that the study also demonstrated increased intracranial hemorrhage and unchanged mortality in physicians who took daily aspirin.

The authors reviewed the reasons why prescribers might default to daily low-dose aspirin when a prescription anticoagulant is a more appropriate and effective choice. They also presented the evidence behind some key facts:

· As thromboprophylaxis for stroke after AF, aspirin is ineffective and has a risk of bleeding similar to prescription anticoagulants.

· Most updated guidelines now use CHA₂DS₂-VASc score for risk stratification in AF and can identify truly low-risk patients who require neither aspirin nor an anticoagulant.

· The vast majority of patients with AF have CHA₂DS₂-VASc scores that support oral anticoagulant prescription.

· Although oral anticoagulants are more costly than aspirin, economic analyses have repeatedly deemed them more cost effective.

The authors strongly recommended that current guidelines remove aspirin as an option for stroke prevention in AF patients who lack the comorbid conditions requiring its use. The United Kingdom’s National Institute for Health and Care Excellence has already made that move, and the FDA issued a statement in May 2014 indicating that current evidence does not support the general use of aspirin for primary prevention of a heart attack or stroke, though the US agency confirmed aspirin’s role in secondary prevention.