Antithrombotic therapy does not reduce the risk of stroke in patients with low-risk atrial fibrillation (AF), with untreated patients appearing to have a better outcome, according to a large community-based study presented at the American College of Cardiology’s 66th Annual Scientific Session. The risk of bleeding associated with antithrombotic therapy outweighs the benefits, the authors concluded.
To define the long-term effect of antithrombotic therapy on stroke risk reduction, the researchers analyzed 56,723 patients diagnosed with AF who were considered low-risk for stroke (defined as a CHADS2 score of 0-1). The mean age of the population was 67 years and 56.6 percent was male. Antithrombotic therapy (initiated within 6 months of AF diagnosis) consisted of:
- warfarin: 1,164 patients
- clopidogrel: 1,802 patients
- aspirin: 9,683 patients
The authors compared the rates of all-cause mortality, cerebrovascular accident (CVA), transient ischemic attack (TIA), and major bleeding among patients receiving either antiplatelet (clopidogrel, aspirin) or warfarin therapies.
The authors demonstrated that low-risk AF patients who received antithrombotic therapy experienced higher rates of stroke and significant bleeding. At five-year follow-up, 4.6 percent of aspirin-prescribed patients experienced a stroke, compared with 2.3 percent of patients not receiving aspirin. Also, 17.6 percent of those using aspirin experienced significant bleeding, compared with 11.5 percent of patients not receiving aspirin (p<0.0001). Among warfarin-prescribed patients, 5.7 percent experienced a stroke versus 2.6 percent of those not receiving warfarin. Bleeding risk was also higher, with 22.3 percent of warfarin-prescribed patients experiencing significant bleeding, compared with 12.3 percent of those not receiving warfarin (p<0.0001).
The researchers concluded that anticoagulation and antiplatelet therapies do not lower stroke risk in low-risk AF patients, and also increase the risk of other adverse events. Limitations may include the population sample and lack of randomization.
Source: Golive A, May H, Bair T, et al. Long term outcomes and risk stratification in atrial fibrillation patients with low risk Chads2 ≤1 with antithrombotic therapy. Abstract 1134M-17. Presented at the American College of Cardiology’s 66th Annual Scientific Session. March 17, 2017; Washington, DC.