Many AFib patients at highest risk of stroke not receiving recommended oral anticoagulant therapy

Atrial fibrillation (AF) is the most common cardiac arrhythmia, with an estimated 1 in 4 lifetime risk in those older than 40 years and a projected increase in prevalence to approximately 5.6 million affected individuals by 2050 in the United States. Atrial fibrillation imparts stroke risk, and risk stratification schemes that include the CHADS2 score and, more recently, the CHA2DS2-VASc score have been developed to estimate the risk of thromboembolism (blood clot) in patients with AF based on specific risk factors. The extent to which prescription of oral anticoagulants (OACs) increases as the risk of stroke increases is not well known.

This study included 429,417 outpatients with AF enrolled in the American College of Cardiology National Cardiovascular Data Registry's PINNACLE Registry between January 2008 and December 2012. As a measure of stroke risk, the researchers calculated the CHADS2 score and the CHA2DS2-VASc score for all patients, and examined the association between increased stroke risk score and prescription of an OAC.

Prescribed treatment consisted of an OAC (45 percent of patients), aspirin only (26 percent), aspirin plus a thienopyridine (5.5 percent), or no antithrombotic therapy (24 percent). Each 1-point increase in risk score was associated with increased odds of OAC prescription compared with aspirin-only prescription. However, a plateau of OAC prescription was observed, with less than half of high-risk patients receiving an OAC prescription.

"These findings draw attention to important gaps in appropriate treatment of patients with AF at the highest risk of stroke and highlight opportunities to understand the reasons behind these gaps and insights to improve them," the authors write.