The large, long-term study showed that while stroke risk scores increased, patients at the greatest risk were still being under-prescribed based on current guidelines.
“Despite a well-known association of AF with stroke, we found a significant lack of oral anticoagulant prescribed to reduce blood clots in high-risk patients. This is a wake-up call,” lead author Jonathan C. Hsu, MD, a cardiologist and assistant clinical professor of medicine at UC San Diego School of Medicine, said in a statement. “As the number of stroke cases in AF patients increase annually in the United States, our findings draw attention to a treatment gap in a demographic who may need these therapies the most.”
The 4-year study included 429 417 patients (mean age 71.3 (12.9) years, 55.8% male) with AF from the American College of Cardiology National Cardiovascular Data Registry’s PINNACLE (Practice Innovation and Clinical Excellence) Registry. The CHADS2 and CHA2DS2-VASc scores served as measures of stroke risk in all patients.
Among the participants, treatment included oral anticoagulant (44.9%; 90.3% on warfarin), aspirin only (25.9%), aspirin plus a thienopyridine (5.5%) or no antithrombotic therapy (23.8%). Each 1-point increase in both the CHADS2 and CHA2DS2-VASc scores was associated with increased odds of oral anticoagulant compared to aspirin-only prescription (CHADS2: adjusted odds ratio, 1.158; 95% CI, 1.144-1.172; P < .001), (CHA2DS2-VASc: adjusted odds ratio, 1.163; 95% CI, 1.157-1.169; P < .001).
Prevalence of oral anticoagulant prescriptions did not exceed 50% even in high-risk patients whose CHADS2 and CHA2DS2-VASc scores exceeded 3 or 4, respectively.
“Physicians may be avoiding additional therapy in certain patients taking antiplatelet medications because of the increased risk of bleeding associated with the oral anticoagulants,” said Dr Hsu. “It may be thought of as too dangerous for these sicker patients, but we still know that in most of these patients the benefits of blood thinning to reduce the risk of stroke outweigh the risks of bleeding.”
Hsu JC, Maddox TM, Kennedy KF, et al. Oral Anticoagulant Therapy Prescription in Patients With Atrial Fibrillation Across the Spectrum of Stroke Risk – Insights From the NCDR PINNACLE Registry. JAMA Cardiol. 2016; doi: 10.1001/jamacardio.2015.0374.