Summary of Evidence-Based Guideline Update: Prevention of Stroke in Nonvalvular Atrial Fibrillation. Report of the Guideline Development Subcommittee of the American Academy of Neurology

Study Questions:

To update the 1998 American Academy of Neurology (AAN) practice parameter for stroke prevention in atrial fibrillation (AF), the investigators posed the following: How often do various monitoring strategies identify AF in patients with cryptogenic stroke? Which therapies reduce stroke risk and severity with the least risk of hemorrhage?


The investigators identified relevant articles published between 1998 and 2013.


The most common technique to identify AF in patients with cryptogenic stroke was Holter monitoring. Longer monitoring was associated with a higher rate of AF detection. Other findings included:

• Novel oral anticoagulants (NOACs; dabigatran, rivaroxaban, and apixaban) are as good or better than warfarin in prevention of thromboembolism, with a lower risk of intracranial hemorrhage (ICH), but with a higher (or similar for Apixaban) risk of gastrointestinal bleeding.

• Warfarin is superior to dual antiplatelet therapy with aspirin (ASA) plus clopidogrel, but is associated with a higher risk of ICH.

• Clopidogrel plus ASA is superior to ASA alone in patients who are not candidates for warfarin, but at a higher risk of bleeding.

• Low-dose ASA plus warfarin probably increases hemorrhagic risk.

• Bleeding risk of ASA is similar to that of apixaban.

• Warfarin is more effective than ASA in the elderly (i.e., ages >75 years), with similar rates of extracranial bleeding.


The authors proposed the following recommendations among others:

1. A longer monitoring period (>1 week) is more likely to identify undiagnosed AF in patients with cryptogenic stroke as compared to a shorter duration (e.g., 24 hours).

2. It is reasonable to withhold oral anticoagulation in AF patients without additional risk factors. Either ASA or no therapy may be appropriate for such patients.

3. Oral anticoagulation should be offered to the elderly, given the favorable risk/benefit ratio.

4. Patients doing well on warfarin should remain on warfarin. Those who are dissatisfied with warfarin or at relatively high risk for ICH should be considered for therapy with NOACs.


These findings and recommendations by the AAN should be familiar to professionals in cardiovascular medicine. In addition, an implantable loop recorder may be associated with a higher yield of undiagnosed AF in patients with unexplained stroke than conventional monitoring. Appendage occlusion devices are effective in stroke prevention in patients who are not thought to be candidates for oral anticoagulation.

Clinical Topics: Anticoagulation Management, Arrhythmias and Clinical EP, Anticoagulation Management and Atrial Fibrillation, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Novel Agents

Keywords: Morpholines, Platelet Aggregation Inhibitors, Thiophenes, Warfarin, Ticlopidine, Risk Factors, Prostheses and Implants, Thromboembolism, beta-Alanine, Benzimidazoles, Cesium Radioisotopes, Electrocardiography, Ambulatory, Pyridones, Risk Assessment, United States, Odds Ratio, Stroke, Pyrazoles, Blood Coagulation, Intracranial Hemorrhages, Atrial Fibrillation, Strontium Radioisotopes, Hemorrhage

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