Experts on atrial fibrillation (AF) who are members of the AF-SCREEN International Collaboration summarized the evidence regarding strategies for identifying new AF after stroke in a white paper published in Circulation.
The white paper authors noted that AF increases the risk for thromboembolism and can be used as a marker for atrial myopathy. Signs of atrial myopathy may be helpful for guiding AF monitoring, particularly in cases of ischemic stroke of uncertain cause. The authors also provided definitions of atrial arrhythmias, AF and of different stroke types, including cryptogenic stroke and embolic stroke of undetermined source (ESUS).
Current evidence recommends that patients who have experienced a stroke be given electrocardiograms (ECGs) verified by a health professional experienced in ECG rhythm interpretation in an effort to detect AF.
Current Understanding of ESUS
ESUS refers to a cryptogenic stroke without competing causes or incomplete diagnostic evaluation and is characterized by a non-lacunar brain infarction without hemodynamically relevant stenosis. Based on current evidence from clinical trials, it is unclear whether patients who have experienced an ESUS will benefit from oral anticoagulation (OAC) therapy. According to the authors, patients who fulfill ESUS criteria should not be treated with novel OACs (NOACs) — a treatment not supported by evidence in this population — or withheld from prolonged ECG monitoring. In certain populations with ESUS (ie, with atrial enlargement or of advanced age), patients may benefit from treatment with a NOAC vs aspirin, as supported by results from the NAVIGATE ESUS and RE-SPECT ESUS (Clinicaltrials.gov identifiers: NCT02313909 and NCT02239120, respectively) trials. The definition of ESUS may need revision and subtypes should be further specified, according to the white paper authors.
Transient Ischemic Attack (TIA)
When new AF is detected by ECG monitoring after a stroke or TIA, an expert consensus of the AF-SCREEEN collaboration recommends OAC therapy. Such an approach is thought to reduce the risk for subsequent stroke or systemic embolism, particularly in patients with additional risk factors for stroke. The white paper also describes evidence suggesting that continuous poststroke ECG monitoring should be performed for ≥72 hours in patients with ischemic stroke or TIA, a longer period than the 24-hour Holter ECG monitoring recommendation minimum.
Increasing AF Detection Yield
Several factors for increasing AF detection yield are mentioned, including the presence of cardiac imaging markers and blood biomarkers (ie, natriuretic peptides), as well as excessive atrial ectopy. Increased levels of C-reactive protein and troponin may also be helpful for detecting AF after stroke and determining which patients may benefit from more prolonged and/or intensive poststroke ECG monitoring. Age, demographics, heart failure, and stroke severity may also facilitate the identification of patients who should receive more intensive monitoring.
Harms Associated With Monitoring
The authors also highlighted potential harms associated with monitoring for AF after stroke, which are often due to OAC overtreatment that may increase the risk of bleeding. The authors recommend a risk-benefit assessment of OAC therapy for the treatment of AF after stroke.
AF monitoring is also associated with an increased use of tests and healthcare resources. Bulky devices such as that used for Holter ECG monitoring can be uncomfortable and may affect patient compliance. Many patients have reported preferring more compact devices that do not interfere with activities of daily living. Smart watches with an ECG rhythm strip may improve patient compliance; however, studies need to be conducted to examine the accuracy and validity of these devices for AF detection.
Knowledge Gaps and Conclusions
Several knowledge gaps for detecting AF after stroke remain, including the nature of methods for determining the persistence and recurrence rate of paroxysmal AF in the acute phase of stroke. The authors noted that additional validated cost-efficient methods for poststroke AF monitoring should be developed and used by healthcare systems with limited resources.
According to the white paper authors, guidelines on ECG monitoring for AF after stroke are vague in terms of length and type of monitoring. Although many national and international organizations provide recommendations for monitoring, these lack a thorough and standardized consensus for detecting AF after stroke. “Further evidence is needed to establish risk-stratified ECG monitoring strategies that are safe, effective, and cost-effective,” noted the authors.
Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Schnabel RB, Haeusler KG, Healey JS, et al. Searching for atrial fibrillation poststroke: a white paper of the AF-SCREEN International Collaboration. Circulation. 2019;140(22):1834-1850.