Antiplatelet Therapy

The evidence supporting antiplatelet therapy for stroke prevention in patients with AF is extremely limited. Aspirin is the most common antiplatelet therapy, but no studies, with the exception of the Stroke Prevention in Atrial Fibrillation (SPAF-1) trial, have shown a benefit of aspirin alone in preventing stroke in patients with AF.1 A meta-analysis found a 19% reduction in stroke with aspirin vs no therapy, but this finding was not statistically significant and was driven by the positive findings of the SPAF-1 trial.7 Aspirin may be considered for patients with a CHA2DS2-VASc score of 1, but it is less effective than warfarin or DOACs for preventing strokes.1,7,18

The combination of clopidogrel and aspirin has also been studied. In clinical trials, it reduced the relative risk of stroke by 28% compared with aspirin alone, but it also increased the risk of major bleeding by 57%.1 Combination clopidogrel plus aspirin has been shown to be inferior to warfarin for stroke prevention.1 Antiplatelet therapy should not be used in combination with anticoagulation therapy due to the increased risk of major bleeding.6

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Case Presentation, Continued: Shared Decision-Making and Management Plan

Following consultation with his primary care provider, shared decision-making is instituted with Frank to discuss oral anticoagulation options. Considerations covered include the risks and benefits of the proposed therapy, cost, type of follow-up needed, and any lifestyle limitations or quality-of-life concerns that may affect this choice.8

Frank does not think that the frequent monitoring required with warfarin will fit with his lifestyle. He chooses to start dabigatran 150 mg twice daily. Ongoing monitoring should be performed at follow-up visits to check for treatment adherence, thromboembolism, bleeding, side effects, and co-medications.19 Hemoglobin and renal and liver function should be monitored at regular intervals with the frequency depending on the patient’s history and CrCl values.19 In Frank’s case, blood sampling should be performed every 6 months because his CrCl is between 30 and 60 mL/min.

The next year, Frank’s creatinine clearance was found to have decreased to 28 mL/min. He has had no adverse events related to his treatment with dabigatran.

Summary

Patients with AF are at increased risk of stroke, but many people may not experience any symptoms. These patients may not be diagnosed with AF until a healthcare provider checks their heart rate or listens to their heart during a routine checkup. Patients diagnosed with NVAF should be assessed for stroke risk and bleeding risk to determine if antithrombotic therapy is appropriate, and clinicians should discuss both the risk of stroke and the risk of bleeding with patients. If oral anticoagulant therapy is appropriate, several options are now available for consideration including warfarin, the direct thrombin inhibitor dabigatran, and the direct factor Xa inhibitors apixaban, edoxaban, and rivaroxaban. When selecting an antithrombotic therapy, factors that should be considered and discussed with the patient include the risks and benefits of the therapy and the feasibility of adherence (including cost, type of follow-up required, and quality of life). Patients should return for ongoing review of their treatment on a regular basis.

Charles P. Vega, MD, is clinical professor of family medicine; director of the Program in Medical Education for the Latino Community (PRIME-LC); and associate dean for diversity and inclusion at the University of California-Irvine School of Medicine.

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