Prevalence of Inadequate Therapeutic Anticoagulation for Afib Preceding Ischemic Stroke Examined

A retrospective study reported in JAMA confirmed an association between decreased stroke severity and anticoagulation therapy in patients with atrial fibrillation (AF) who were hospitalized for ischemic stroke. Additionally, inadequate pre-stroke anticoagulation was found to be prevalent in such patients.¹

Based on research showing that vitamin K antagonists and non-vitamin K antagonist oral anticoagulants (NOACs) decrease stroke risk, current guidelines from the American Heart Association recommend their use in high-risk patients with AF.² However, other results demonstrate inadequate use of anticoagulation therapy in US physician practices and hospitals.^3.4   

Previous data also suggest that, along with reducing stroke risk, warfarin may decrease the severity of a stroke if it does occur, although these findings preceded the era of NOACs.⁵ Noting the need for current data on the topic, the researchers in the new study investigated links between preceding antithrombotic therapy and outcomes in 94,474 AF patients who were hospitalized for acute ischemic stroke at 1622 US hospitals.

The main outcomes were stroke severity at the time of admission, per the National Institutes of Health Stroke Scale, and in-hospital mortality. Functional outcome at hospital discharge was the secondary outcome.

In line with earlier findings, the analysis revealed inadequate pre-stroke anticoagulation therapy in this patient group:

• 7.6% of patients were receiving therapeutic warfarin, and 8.8% were receiving NOACs
• 83.6% of patients were not receiving therapeutic anticoagulation: 30.3% received no antithrombotic treatment, 13.5% received subtherapeutic warfarin, and 39.9% received antiplatelet therapy only
• 83.5% of high-risk patients, as indicated by a pre-stroke CHA2DS2-VASc score of ≥2, were not receiving therapeutic anticoagulation

After multivariable adjustment for potential confounders such as age, sex, race/ethnicity, medical history, and the use of certain medications, lower odds of moderate or severe stroke were observed with the use of therapeutic warfarin (adjusted odds ratio [OR]: 0.56; 95% CI, 0.51-0.60), NOACs (OR: 0.65; 95% CI, 0.61-0.71), or antiplatelet therapy (OR: 0.88; 95% CI, 0.84-0.92) compared with no antithrombotic therapy

After multivariable adjustment, lower in-hospital mortality was associated with the use of therapeutic warfarin (OR: 0.75; 95% CI, 0.67-0.85), NOACs (OR: 0.79; CI, 0.72-0.88), and antiplatelet therapy (OR: 0.83, 95% CI, 0.78-0.88) vs no antithrombotic therapy.

In addition, patients receiving antithrombotic treatment were more likely to have better functional outcomes as indicated by a modified Rankin Scale (mRS) score of 0-1 or 0-2 at discharge.

“Based on results from pivotal anticoagulation trials and the prevalence of inadequate therapeutic anticoagulation observed in our study, a substantial number of strokes may be due to underuse of or inadequate anticoagulation in AF,” the investigators concluded.

Disclosures: The authors report numerous disclosures, which are detailed in the paper.

References

1. Xian Y, O’Brien EC, Liang L, et al. Association of preceding antithrombotic treatment with acute ischemic stroke severity and in-hospital outcomes among patients with atrial fibrillation. JAMA. 2017;317(10):1057-1067.
2. Meschia JF, Bushnell C, Boden-Albala B, et al. Guidelines for the primary prevention of stroke: a statement for healthcare professionals from the American Heart Association/American Stroke Association. Stroke. 2014;45(12):3754-3832. doi:10.1161/STR.0000000000000046
3. Dlott JS, George RA, Huang X, et al. National assessment of warfarin anticoagulation therapy for stroke prevention in atrial fibrillation. Circulation. 2014;129(13):1407-1414. doi:10.1161/CIRCULATIONAHA.113.002601
4. Waldo AL Becker RC, Tapson VF, Colgan KJ; NABOR Steering Committee. Hospitalized patients with atrial fibrillation and a high risk of stroke are not being provided with adequate anticoagulation. J Am Coll Cardiol. 2005; 46(9):1729-36. doi:10.1016/j.jacc.2005.06.077
5. Hylek EM, Go AS, Chang Y, et al. Effect of intensity of oral anticoagulation on stroke severity and mortality in atrial fibrillation. N Engl J Med. 2003;349(11):1019-1026.