Top Things to Know: Subclinical and Device Detected Atrial Fibrillation Pondering the Knowledge Gap
Published: November 07, 2019
- Each year, 16.9 million people worldwide have a stroke, and in 20-40% of those cases, the cause is unknown. Of these unexplained strokes, about 10-30% may be due to undetected atrial fibrillation (AF).
- Better detection and understanding of subclinical atrial fibrillation (SCAF) may assist in determining the best screening and treatment for it and could prevent many strokes.
- This scientific statement explores the evidence regarding the prevalence, clinical significance and management of atrial arrhythmias detected by implantable and wearable cardiac devices.
- AF has traditionally been defined by detection of the arrhythmia using a 12-lead electrocardiogram (ECG) and has been diagnosed independent of the duration of the arrhythmia or any associated symptoms.
- With the advent of continuous rhythm monitoring using cardiac implanted devices (CIEDs) with automated atrial rhythm detection, a new category of atrial arrhythmias are defined as atrial high rate episodes (AHREs); atrial events that meet programmed or other defined atrial high rate criteria.
- Predictors of SCAF are discussed in this paper along with the relationship to stroke, the association with embolic stroke of undetermined source (ESUS), progression to clinical AF, and the relationship between AF and heart failure (HF).
- Optimal primary prevention in SCAF is still uncertain for many patients. There are many unanswered questions related to SCAF such as the benefit of anticoagulation when the risk of stroke is low to intermediate and the management of risk factors to prevent AF progression. Ongoing clinical trials may inform management of these patients.
- In the absence of clear information, shared decision making with patients about specific management is critical when information is shared between the clinician and patient.
- Several factors should be considered if SCAF is detected: first, electrocardiograms should be reviewed to confirm SCAF, exclude false positive results from CIEDs, and quantify the longest continuous episode and the highest daily burden (since stroke risk increases with longer durations and higher burden). Clinicians should assess traditional stroke risk factors such as age, diabetes hypertension and HF.
- At this time, the data is incomplete, so it seems reasonable to defer anticoagulation for patients with no stroke risk factors or those who have very brief AHREs but consider anticoagulation for longer episodes in patients who have stroke or TIA or other stroke risk factors.
Citation
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 [published online ahead of print November 7, 2019]. Circulation. doi: 10.1161/CIR.0000000000000740.