Diagnosis of AF
Reports suggest AF is an underdiagnosed condition,5 particularly common in older populations and in those with heart failure. 20123
Atrial Fibrillation might be suspected in individuals presenting with common symptoms of the condition, including heart palpitations, fatigue, dizziness, light-headedness, and dyspnoea.
A diagnosis of AF is often made by pulse palpation, in which the pulse is classically described as being ‘irregularly irregular’. Confirmation of AF requires a rhythm recording displaying the electrical activity of the heart using an documentation using an electrocardiogram (ECG or EKG ), showing the typical pattern of AF: completely irregular RR intervals, an absence of P waves, and coarse or fine fibrillation waves at baseline.
How to diagnose?
A diagnosis of Atrial Fibrillation (AF or AFib) is often made by pulse palpation, in which the pulse is classically described as being ‘irregularly irregular’. A systematic review concluded that pulse rate is 94% sensitive and 72% specific for diagnosis (positive likelihood ratio = 3.4; negative likelihood ratio = 0.08).1 Confirmation of AF requires a rhythm recording displaying the electrical activity of the heart using an electrocardiogram (ECG or EKG ), showing the typical pattern of AF: completely irregular RR intervals, an absence of P waves, and coarse or fine fibrillation waves at baseline. An episode lasting at least 30 seconds is diagnostic.2,3 This is traditionally carried out using a standard 12-lead ECG or continuous ambulatory ECG monitoring. ECG changes can be subtle and interpretation should be performed by a competent clinical practitioner to ensure accuracy.
A normal test result however does not completely rule out the presence of AF, as the ECG may not capture paroxysmal arrhythmia. In these cases, a Holter monitor (24-hour recording) or an event monitor (7–30 day recording) may be required to measure the patient’s heart rhythm over a prolonged period of time.1
The history and physical examination of the patient are focused on identifying risk factors (e.g. excessive alcohol consumption), comorbidities, and physical findings of AF. A patient’s medical history should consider the following items:1,3
- Cardiac and non-cardiac aetiologies
- Onset and duration of arrhythmia, aggravating and alleviating factors, and severity of associated symptoms
- Presence of common AF symptoms (e.g. fatigue)
- Comorbidities (e.g. thyroid disease)
- Use of any new medications or supplements
- Use of illicit drugs, alcohol, or diet pills
A physical examination is required to exclude valvular heart disease, thyrotoxicosis (presence of excess thyroid hormone), and heart failure. It should assess:1,3
- Blood pressure
- Heart rate
- Presence of cardiac murmurs (e.g. aortic stenosis)
- Evidence of heart failure (pulmonary rales, S3 gallop, peripheral pulses, and jugular venous distension)
Initial blood tests should include a complete blood count, an electrolyte panel, thyroid-stimulating hormone and liver and kidney function tests.1
A chest radiograph is recommended to exclude pulmonary disease and heart failure and assess the blood level of thyroid stimulating hormone to exclude thyrotoxicosis. Transthoracic echocardiography should be used to detect underlying structural disease (e.g. valvular disease) and assess LV size and function (systolic and diastolic), atrial size and right heart function.2,3
Additional testing may be needed depending on the patients’ history and risk factors. These may include stress echocardiography, nuclear perfusion imaging, or cardiac catheterisation to evaluate for ischemia or coronary artery disease; drug screening in selected cases and a sleep study if sleep apnoea is suspected.1
Both systemic and opportunistic screening increase the rate of detection of new AF cases compared to routine practice in patients >65years. Opportunistic screening demands less effort from GPs.4 European guidelines have recommended opportunistic screening by pulse taking or ECG in patients over 65 years since 2012.3
1. Gutierrez E, Blanchard D (2016) Diagnosis and Treatment of Atrial Fibrillation. Am Fam Physician 15;94(6):442-452. 2. Lip GYH, et al. (2016) Atrial Fibrillation. Nature Reviews, Disease Primers. Vol. 2. doi:10.1038/nrdp.2016.16 . Published online 31 March 2016. 3. Kirchhof P, Benussi S, Kotecha D, Ahlsson A, Atar D et al. (2016) 2016 ESC Guidelines for the management of atrial fibrillation developed in collaboration with EACTS. Eur Heart J 37 (38): 2893-2962. 4. Mairesse GH, et al. (2017) Screening for atrial fibrillation: a European Heart Rhythm Association (EHRA) consensus document endorsed by the Heart Rhythm Society (HRS), Asia Pacific Heart Rhythm Society (APHRS), and Sociedad Latinoamericana de Estimulación Cardíaca y Electrofisiología (SOLAECE). Europace. 2017 Oct 1;19(10):1589-1623. doi: 10.1093/europace/eux177. 5. Morillo CA, Banjeree A, Perel P, Wood D, Jouven X (2017) Atrial fibrillation: the current epidemic. Journal of Geriatric Cardiology (2017) 14: 195-203
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