Net Clinical Benefit for Anticoagulation, Aspirin, or No Therapy in Low-Risk AF

Jul 21, 2015
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Authors:
Lip GY, Skjøth F, Rasmussen LH, Nielsen PB, Larsen TB.
Citation:
Net Clinical Benefit for Oral Anticoagulation, Aspirin, or No Therapy in Nonvalvular Atrial Fibrillation Patients With 1 Additional Risk Factor of the CHA2DS2-VASc Score (Beyond Sex). J Am Coll Cardiol 2015;66:488-490.
Summary By:
Geoffrey D. Barnes, MD, MSc, FACC

Study Questions:

What is the net clinical benefit (NCB) of aspirin or warfarin as compared to no antithrombotic therapy among atrial fibrillation (AF) patients at low risk for stroke?

Methods:

Using the nationwide Danish cohort database, patients with incident AF diagnosed between 1998 and 2012 were identified. Patients were included if the CHA2DS2-VASc score was 1 (for men) or 2 (for women) at the time of hospital discharge and categorized based on antithrombotic therapy into a warfarin, aspirin, or no therapy cohort. The primary endpoint was NCB, defined as a weighted sum of rate difference between those treated and those not treated (or treated with lesser antithrombotic medications). Events were given weights of 1 for ischemic stroke, 2.44 for intracranial hemorrhage, 0.67 for major bleeding, and 0.86 for myocardial infarction, as identified by hazard ratios from the entire Danish AF cohort with 1-year follow-up.

Results:

In low-risk AF patients, warfarin therapy was associated with a NCB of 1.68 (95% confidence interval [CI], 0.55-2.81) as compared to no therapy, and 2.22 (95% CI, 0.59-3.85) as compared to aspirin. Aspirin therapy was associated with a NCB of -0.54 (95% CI, -1.84 to 0.75) as compared to no therapy.

Conclusions:

The authors concluded that warfarin therapy is associated with a positive advantage and NCT as compared to no therapy or aspirin therapy in AF patients with a single risk factor for stroke other than gender.

Perspective:

This study attempts to integrate benefits and harms of antithrombotic therapy in AF patients with only a single risk factor for stroke by performing a NCB analysis. While the weights used in this analysis lack complete justification, they appear similar to weights from prior NCB studies. The authors also acknowledge that this study was limited to warfarin therapy, and therefore, caution is needed when extrapolating the findings to direct oral anticoagulants given their lower rates of intracranial hemorrhage, but modestly increased risk of gastrointestinal bleeding rates.

Keywords: Anticoagulants, Arrhythmias, Cardiac, Aspirin, Atrial Fibrillation, Fibrinolytic Agents, Intracranial Hemorrhages, Myocardial Infarction, Primary Prevention, Risk Factors, Stroke, Warfarin


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