Anticoagulation in Subclinical Atrial Fibrillation and the Prevention of Stroke

May is National Stroke Awareness Month. This initiative began in May 1989 to promote public awareness and reduce the incidence and associated burden of stroke in the United States.1  Despite ongoing efforts, stroke remains a leading cause of death and long-term disability in the United States.2-4 Every year about 795,000 people in the United States have a stroke.2    

Stroke can be preventable. One of its major risk factors, atrial Fibrillation, affects as many as 2.2 million Americans.  In people over 80 years of age, atrial fibrillation remains the direct cause of 1 in 4 strokes.5-6 There are documented benefits to the administration of direct oral anticoagulants and vitamin K antagonists in new-onset atrial fibrillation (> 24-hour duration).  There is controversy on the use of these agents with asymptomatic, subclinical atrial fibrillation (SCAF), or atrial fibrillation (< 24 hour duration).7-8   Results from a meta-analysis of 50 studies suggested SCAF being commonly detected within in patients after a stroke.9   Studies also report shorter episodes of SCAF associated with a higher likelihood of subsequent longer episodes of SCAF and nearly six times higher risk of clinical atrial fibrillation.10-11

It has been well documented that the use of cardiac implantable electronic devices and wearable monitors leading to increased detection of subclinical atrial fibrillation in patients. It is argued that in efforts to reduce the stroke risk, with the detection of subclinical atrial fibrillation, clinicians may have a window of opportunity in the initiation of anticoagulation. The American Heart Association published a scientific statement on the prevalence, clinical significance, and management of subclinical atrial fibrillation. It also highlighted current gaps in knowledge and areas of controversy around the treatment of subclinical atrial fibrillation.8

With the lack of clearly defined thresholds of atrial fibrillation burden to initiate oral anticoagulation, clinicians are faced with having to weight the clinical benefits and contraindications to anticoagulation therapy for patients with SCAF.8  A population health approach, leveraging the use of the electronic medical record may present alternatives into risk stratification and therapeutic management of direct oral anticoagulants .6 Options such as the use of anticoagulation clinics may need to be explored in the case of oral anticoagulant agents that do not require routine laboratory monitoring.

 Findings from two ongoing clinical trials in patients with Cardiac Implanted Electronic Devices-detected SCAF will inform on the management of SCAF in the prevention of strokes: the ARTESiA (Apixaban for the Reduction of Thrombo-Embolism in Patients With Device-Detected Subclinical Atrial Fibrillation; NCT 01938248)41 and NOAH (Non–Vitamin K Antagonist Oral Anticoagulants in Patients With Atrial High Rate Episodes; NCT 02618577).8  Until then, it will be important for clinicians to continue working, following a patient centered approach. Factors such as patient goals and preferences, adherence, gaps in knowledge, will need to be addressed in order to support a more personalized, therapeutic approach.8


  1. Bush, George. Peters, Gerhard; Woolley, John T. (eds.). “Proclamation 5975—National Stroke Awareness Month, 1989”. The American Presidency Project. University of California at Santa Barbara.
  2. Kochanek KD, Xu JQ, Murphy SL, Arias E. Mortality in the United States, 2013. NCHS Data Brief, No. 178. Hyattsville, MD: National Center for Health Statistics, Centers for Disease Control and Prevention, Department of Health and Human Services; 2014.
  3. Mozzafarian D, Benjamin EJ, Go AS, Arnett DK, Blaha MJ, Cushman M, et al., on behalf of the American Heart Association Statistics Committee and Stroke Statistics Subcommittee. Heart disease and stroke statistics—2016 update: a report from the American Heart Association. Circulation 2016;133(4):e38–360.
  4. Virani SS, Alonso A, Benjamin EJ, Bittencourt MS, Callaway CW, Carson AP, et al. Heart disease and stroke statistics—2020 update: a report from the American Heart Associationexternal icon. Circulation. 2020;141(9):e139–e596.
  5. National Institute of Neurological Disorders and Stroke. Atrial fibrillation and stroke information. 2019.
  6. Jame S, Barnes G. Stroke and thromboembolism prevention in atrial fibrillation. Heart. 2020;106(1):10-17. doi:10.1136/heartjnl-2019-314898
  7. Healey JS, Amit G, Field TS. Atrial fibrillation and stroke: how much atrial fibrillation is enough to cause a stroke?. Curr Opin Neurol. 2020;33(1):17-23. doi:10.1097/WCO.0000000000000780
  8. Noseworthy PA, Kaufman ES, Chen LY, Chung MK, Elkind MSV, Joglar JA, Leal MA, McCabe PJ, Pokorney SD, Yao X; on behalf of the American Heart Association Council on Clinical Cardiology Electrocardiography and Arrhythmias Committee; Council on Arteriosclerosis, Thrombosis and Vascular Biology; Council on Cardiovascular and Stroke Nursing; and Stroke Council. Subclinical and device-detected atrial fibrillation: pondering the knowledge gap: a scientific statement from the American Heart Association. Circulation. 2019;140:e944–e963. doi: 10.1161/CIR.0000000000000740.
  9. Sposato LA, Cipriano LE, Saposnik G, Ruíz Vargas E, Riccio PM, Hachinski V. Diagnosis of atrial fibrillation after stroke and transient ischaemic attack: a systematic review and meta-analysis. Lancet Neurol. 2015; 14:377–387. doi: 10.1016/S1474-4422(15)70027-X
  10. Mahajan R, Perera T, Elliott AD, Twomey DJ, Kumar S, Munwar DA, Khokhar KB, Thiyagarajah A, Middeldorp ME, Nalliah CJ, et al.. Subclinical device-detected atrial fibrillation and stroke risk: a systematic review and meta-analysis. Eur Heart J. 2018; 39:1407–1415. doi: 10.1093/eurheartj/ehx731
  11. Swiryn S, Orlov MV, Benditt DG, DiMarco JP, Lloyd-Jones DM, Karst E, Qu F, Slawsky MT, Turkel M, Waldo AL; RATE Registry Investigators. Clinical implications of brief device-detected atrial tachyarrhythmias in a cardiac rhythm management device population: results from the Registry of Atrial Tachycardia and Atrial Fibrillation Episodes. Circulation. 2016; 134:1130–1140. doi: 10.1161/CIRCULATIONAHA.115.020252

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