Introduction

Atrial fibrillation (AF) is an abnormal rhythm of the heart (cardiac arrhythmia) where the heart beats faster than usual.¹ The irregularity of a heartbeat that lasts for more than seven days is called a persistent arrhythmia.² In almost 40% of cases, AF is symptomless and first manifests as a stroke. Hence, early diagnosis and treatment of atrial fibrillation are of great importance to prevent the occurrence of stroke.³

Classification of atrial fibrillation

Atrial fibrillation can be classified as one of 3 primary types:²

• Paroxysmal: self-limiting (it resolves by itself) and lasts for less than 7 days
• Persistent: requires medical intervention as it will last for more than 7 days
• Permanent: lasts for more than one year, even with medical intervention

Clinical evaluation

Patient history

History is important for diagnosing and identifying patients at risk of atrial fibrillation. In suspicion of atrial fibrillation, there should be a focus on these key symptoms of AF:⁴ 

• Breathlessness
• Palpitations
• Syncope or dizziness
• Chest discomfort
• Stroke or transient ischaemic attack
• Dyspnea (shortness of breath) on exertion
• Increased lower extremity swelling

History is also important to identify associated risk factors such as hypertension, smoking, alcohol intake, etc.¹

• This also includes questions regarding the following: 
• Duration and frequency of symptoms
• History of triggers
• Previously successful modes of termination
• The use of anti-arrhythmic drugs
• Antecedent cardiac diseases

Physical examination

A physical exam will involve observing or looking for the following:^{1, 3, 5}

• Examination of the pulse by palpating the radial pulse for example, which is the primary screening test for Atrial fibrillation, especially for elders above 65 years of age. Atrial Fibrillation can be identified by the irregularity in the pulse
• The heart rate of the patient generally ranges from 110/min to 140/min
• Evaluation of extremities for oedema and peripheral pulses in both upper and lower extremities
• Integumentary signs of peripheral vascular disease (PVD) include hair loss and skin breakdown

Electrocardiogram (ECG)

If any irregularity of pulse is identified in a person with suspected Atrial fibrillation with or without symptoms, a 12-Lead ECG should be taken.⁴ ECG is important in diagnosing atrial fibrillation, as it measures the electrical activity of the heart. ¹

On ECG, a medical professional will look for the following for the presence of Atrial fibrillation: ¹

• Typical narrow complex ‘irregular irregular’ pattern with no distinguishable p-wave
• Fibrillatory waves may be seen / absent
• Ventricular rate ranges between 80 and 180/min

Continuous ECG monitoring 

A Holter monitor is a type of continuous monitor which is used to continuously monitor the electrical activity of the heart for a period of 24 to 72 hours. The main advantage of the Holter monitor is the capture of ECG data for an extended period of time, rather than a typical ECG, which only captures the electrical activity of the heart for a moment of time. This continuous monitoring allows the detection and analysis of episodes of arrhythmia that might get missed otherwise. ⁶

A Holter monitor itself is a lightweight device with electrodes attached to the chest of the patient. It is connected to a recording device that may be worn on the waist or carried in a convenient pouch. The data is then downloaded from the Holter monitor, and a report is generated, which includes parameters such as total heartbeat, average heart rate, maximum and minimum heart rates, number and type of premature beats, the duration and type of different tachyarrhythmias, and ST segment changes.

By providing a complete review of a patient’s cardiac rhythm, a Holter monitor facilitates accurate diagnosis and treatment guidance. The continuous monitoring allows a specialist to assess the impact of arrhythmias and identify the high-risk patients who may benefit from different treatments.

Assessment of cardiac function with cardiac imaging

Transthoracic echocardiography 

Transthoracic echocardiography (TTE) is a rapid, non-invasive imaging technique that helps in a number of areas. It can be used to assess the structure and function of the heart. It can help identify the underlying cause of atrial fibrillation. It can also identify the risk of thromboembolism in the treatment of Atrial fibrillation.⁷

TTE for assessment of AF aetiology 

TTE identifies the conditions that can predispose someone to Atrial fibrillation, which include:⁷ 

• Left ventricular systolic dysfunction caused by ischaemic or dilated cardiomyopathy
• Left ventricular hypertrophy caused by hypertension
• Valvular heart disease, particularly rheumatic mitral stenosis
• Pericardial disease

TTE for assessment of cardiac structure and function 

TTE should include:⁷

• Quantification of chamber dimensions
• Wall thickness
• Left ventricular systolic and diastolic function
• Valvular function

Left atrial size, left ventricular wall thickness and left ventricular dysfunction are independent predictors for the development of Atrial Fibrillation

Assessment of complications 

The presence of thrombus and left ventricular systolic dysfunction predicts increased mortality.

The following are echocardiographic predictors of thromboembolism in Atrial Fibrillation:

• Valve disease
• Left ventricular systolic dysfunction
• Left atrial dilatation
• Complex aortic atheroma
• Left atrial appendage thrombus 
• Reduced LAA velocities (<20 cm/s)

Transoesophageal echocardiography 

Transoesophageal echocardiography (TOE) is indicated in those people with atrial fibrillation when there is an abnormal finding in their TTE that requires further assessment. In these people, TTE is difficult to perform, and it is essential to exclude cardiac abnormalities. TOE should always be done prior to cardioversion to minimise the risk of stroke.

Intracardiac echocardiography 

This is used for 2D visualisation of the structures and to assess the intracardiac flow. It is also used to guide therapy.

Laboratory blood tests in diagnosis

Laboratory Tests are essential to assess the cause of atrial fibrillation:¹

• Complete Blood Count (CBC) for assessment of infection
• Basic Metabolic Panel (BMP) for electrolyte imbalance
• Thyroid function test (TFT) to test for hyperthyroidism 
• Chest X-ray to evaluate any abnormality in the thorax
• Test for cardiac biomarkers and B-type natriuretic peptide (BMP) to rule out underlying cardiac disorder
• D-dimer test to evaluate for pulmonary embolism

Risk stratification

Stroke risk

Use the CHA₂DS₂-VASc score to assess stroke risk in patients with symptomatic or asymptomatic persistent atrial fibrillation. ⁴

Bleeding risk

Assess for the risk of bleeding:⁴

• Before starting anticoagulation treatment in people with atrial fibrillation
• Reviewing patients already taking anticoagulants

Use the ORBIT bleeding score to predict the absolute bleeding risk, which is more accurate. It is essential to assess the low risk for bleeding, as this increases the confidence and willingness of the patient to take the treatment.

Differential diagnosis

Differential diagnosis includes:¹

• Atrial flutter, while AF has a particular irregular rhythm with absent P-waves, atrial flutter has a regularly irregular rhythm with absent P-waves
• Atrial tachycardia
• Multifocal atrial tachycardia
• Wolf-Parkinson-White syndrome
• Atrioventricular nodal reentry tachycardia

Conclusion

Atrial fibrillation is a prevalent cardiac arrhythmia with significant clinical implications, particularly its association with stroke. Effective management depends on timely recognition, thorough diagnostic evaluation, and appropriate risk stratification to guide therapy. 

By prioritising early detection and tailored treatment, healthcare providers can reduce complications and improve long-term outcomes for patients with atrial fibrillation.