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Atrial Fibrillation and CHA2DS2-VASc Scores of 0 or 1 | Journal Scan
Study Questions:
What are the clinical outcomes of different antithrombotic strategies for atrial fibrillation (AF) patients with a CHA2DS2-VASc score of 0 or 1?
Methods:
Using nationwide Danish records, 39,400 patients discharged between 1998 and 2012 with incident nonvalvular AF and a CHA2DS2-VASc score of 0 or 1 were examined through the end of 2013. Comorbidities, stroke, and bleeding events were identified through claims data and stratified based on treatment type (none, aspirin, or warfarin). Event rates, including stroke, bleeding, and death, were based on an intention-to-treat analysis.
Results:
Event rates were low for untreated AF patients (CHA2DS2-VASc = 0 for men, 1 for women) at 0.47 strokes/100 person-years and 0.97 bleeds/100 person-years. The presence of a single additional stroke risk factor (CHA2DS2-VASc = 1 for men, 2 for women) in untreated AF patients increased the stroke rate to 1.24/100 patient-years and the bleeding rates to 1.97/100 person-years. Presence of a single stroke risk factor was associated with increased hazard ratios (HRs) for stroke (2.65, 95% confidence interval [CI], 2.33-3.01) and bleeding (1.95, 95% CI, 1.77-2.14) in AF patients without antithrombotic treatment. When compared to no antithrombotic treatment, use of aspirin was associated with an HR of 1.40 (95% CI, 1.10-1.78) for stroke and HR of 1.36 (95% CI, 1.14-1.62) for bleeding in AF patients without any stroke risk factors. Similar HRs for the comparison of warfarin to no treatment were 1.54 (95% CI, 1.27-1.87) and 1.51 (95% CI, 1.32-1.76) for stroke and bleeding, respectively. Use of aspirin did not confer any reduction in stroke risk as compared to no treatment in AF patients without stroke risk factors (HR, 1.40; 95% CI, 1.10-1.78) or in AF patients with a single additional stroke risk factor (HR, 1.09; 95% CI, 0.93-1.27). The risk of death was reduced in AF patients with a single additional risk factor (HR, 0.70; 95% CI, 0.64-0.91), but not for AF patients without risk factors (HR, 1.03; 95% CI, 0.88-1.20) for the comparison of warfarin to no treatment.
Conclusions:
The authors concluded that lowest-risk AF patients (CHA2DS2-VASc = 0 for men, 1 for women) have a truly low risk of stroke and bleeding without any benefit of antiplatelet or anticoagulant therapy. The authors also concluded that AF patients with one additional stroke risk factor (CHA2DS2-VASc = 1 for men, 2 for women) have a reduction in death risk with the use of warfarin despite no significant reduction in stroke risk.
Perspective:
In this large, national study of Danish patients with AF, the authors demonstrate that use of any antithrombotic therapy (aspirin or warfarin) provides no benefit in the lowest risk patient group (CHA2DS2-VASc = 0 for men, 1 for women). However, they also demonstrate the benefit of warfarin therapy for patients with a single additional risk factor (CHA2DS2-VASc = 1 for men, 2 for women), particularly for reducing the risk of death. While many practitioners feel that use of aspirin is ‘sufficient’ for younger, otherwise healthy patients at lowest risk for stroke, the authors demonstrate that aspirin therapy may be harmful or inferior to warfarin therapy. Despite the limitations of a nonrandomized, observational design, this study highlights the important nuances of utilizing the CHA2DS2-VASc score for determining appropriate therapy in AF patients. These findings are more consistent with the recommendations of the European Society of Cardiology AF guidelines than the American College of Cardiology/American Heart Association/Heart Rhythm Society AF guidelines, which suggest consideration of no treatment, use of aspirin, or use of anticoagulation in patients with a CHA2DS2-VASc score of 1. Clinicians should calculate a CHA2DS2-VASc score for all nonvalvular AF patients and strongly consider the use of anticoagulation in patients with any stroke risk factors other than gender.
Keywords: Anti-Arrhythmia Agents, Anticoagulants, Arrhythmias, Cardiac, Aspirin, Atrial Fibrillation, Comorbidity, Fibrinolytic Agents, Hemorrhage, Intention to Treat Analysis, Mortality, Risk, Risk Factors, Stroke, Warfarin, Secondary Prevention
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