A Practical Guide to Atrial Fibrillation (AF) for Junior Doctors

Atrial fibrillation (AF) is one of the most common arrhythmias you’ll encounter in the emergency department. While it can present in various ways, understanding how to take a targeted history, perform the necessary physical exam, and determine the appropriate investigations and management plan is essential for all junior doctors. In this blog post, we'll break it down systematically, making it easy to navigate through the assessment and management of AF.

Taking a History

A detailed history is crucial in diagnosing AF, understanding its severity, and determining the best treatment approach. When you encounter a patient with a suspected AF, keep the following questions in mind:

·       Presenting complaint:

·       Ask about symptoms such as palpitations, breathlessness, chest pain, dizziness, or fatigue.

·       Did the symptoms come on suddenly or gradually? A sudden onset might suggest paroxysmal AF or a more acute precipitant like pulmonary embolism or acute coronary syndrome (ACS).

·       How long has the patient been symptomatic? This helps in determining the duration of the AF episode, which has implications for management (e.g., anticoagulation and rhythm control).

·       Risk factors:

·       Investigate the patient's history of conditions that predispose them to AF:

·       Hypertension, heart failure, ischemic heart disease, valvular heart disease (especially mitral stenosis), hyperthyroidism, and diabetes.

·       Inquire about any previous history of stroke or transient ischemic attack (TIA).

·       Ask about any family history of arrhythmias or cardiovascular disease.

·       Medications:

·       Review the patient's current medications, especially anticoagulants (e.g., warfarin, apixaban, rivaroxaban), and any pro-arrhythmic drugs (e.g., digoxin, beta-blockers).

·       Check if the patient has any contraindications to anticoagulation or history of non-compliance.

·       Social history:

·       Alcohol consumption (heavy drinking or binge drinking can trigger AF).

·       Smoking and recreational drug use (e.g., cocaine or stimulants).

·       Symptoms of other conditions:

·       Ask about symptoms of hyperthyroidism (e.g., weight loss, tremors) or acute coronary syndrome (e.g., chest pain radiating to the arm, jaw, or back).

Examination

On physical examination, look for signs that can confirm the diagnosis and give clues to the underlying cause of AF:

·       General inspection:

·       Is the patient in respiratory distress? Severe breathlessness or signs of heart failure (e.g., raised jugular venous pressure (JVP), peripheral edema) can point to a more acute or decompensated presentation.

·       Observe for signs of thyroid disease (e.g., exophthalmos or a goiter).

·       Pulse:

·       Check for an irregularly irregular pulse, which is the hallmark of AF. The pulse will be rapid and variable, with no distinct pattern of regularity.

·       Measure the heart rate – AF can present with a rate ranging from 100 to 160 bpm, but patients can also have slow ventricular responses.

·       Auscultation:

·       Auscultate the heart for an absent "P" wave and a rapid, irregularly irregular rhythm.

·       Listen for signs of heart failure, such as an S3 gallop (which may suggest left ventricular dysfunction).

·       Respiratory exam:

·       Listen for signs of pulmonary edema (crackles, wheezing, or signs of pleural effusion).

·       Peripheral exam:

·       Check for signs of stroke, especially if the patient has been in AF for some time. Neurological signs (e.g., hemiparesis, facial droop) could indicate an embolic event.

Investigations

Now, let’s look at the key investigations to confirm the diagnosis, assess the severity of AF, and guide management.

·       ECG (Electrocardiogram):

·       This is the cornerstone of diagnosis. Look for an irregularly irregular rhythm with absent P waves, and an irregular ventricular response. The baseline will be chaotic.

·       In cases of AF with rapid ventricular response, consider whether this is contributing to hemodynamic instability or symptoms like chest pain and breathlessness.

·       Blood tests:

·       Full blood count – Check for anemia (which can precipitate AF).

·       Thyroid function tests – Hyperthyroidism can cause or exacerbate AF.

·       Renal function tests and electrolytes – Electrolyte imbalances (e.g., low potassium or magnesium) can trigger AF.

·       D-dimer – In case of suspicion of pulmonary embolism or deep vein thrombosis as the underlying cause.

·       Chest X-ray:

·       This can help assess heart size (to identify heart failure or structural heart disease) and check for lung pathology (e.g., pneumonia or pulmonary edema).

·       Echocardiogram:

·       Not always needed in the ED setting, but an urgent echocardiogram may be needed if the patient is unstable or if you suspect structural heart disease (valvular pathology, atrial enlargement, or left ventricular dysfunction).

Management Plan

Management of AF can be divided into acute management and long-term management. The approach depends on the severity of symptoms, the duration of the episode, and the patient's underlying risk factors.

·       Acute management (Rate vs. Rhythm control):

·       Rate control:

·       For stable patients with AF and a ventricular rate >100 bpm, beta-blockers (e.g., metoprolol) or calcium channel blockers (e.g., diltiazem) are commonly used.

·       If the patient has heart failure with reduced ejection fraction (HFrEF), digoxin may be more appropriate, though it’s less commonly used nowadays due to potential toxicity and poor control.

·       Rhythm control:

·       If the AF is new-onset and the patient is stable, chemical cardioversion can be attempted with amiodarone or flecainide(if no contraindications like structural heart disease). However, electrical cardioversion may be needed in patients who are symptomatic or if pharmacologic attempts fail.

·       If the AF is longstanding, rhythm control may still be attempted in certain patients, but rate control is often preferred in the elderly or those with heart failure.

·       Anticoagulation:

·       Assess the patient's CHA2DS2-VASc score to evaluate stroke risk. Patients with a score of 2 or more should be offered anticoagulation, usually with DOACs (e.g., apixaban, rivaroxaban) or warfarin if the patient is at higher risk of embolism.

·       For patients with recent onset AF (<48 hours) and low risk of thromboembolism, anticoagulation may not be immediately necessary. However, if the AF is >48 hours or if the onset is unclear, anticoagulation is needed prior to cardioversion.

·       Hospital Admission:

·       Admission to hospital should be considered for patients with:

·       Unstable vital signs (e.g., hypotension, shock, or significant symptoms).

·       Uncontrolled AF despite treatment.

·       Associated complications (e.g., stroke, heart failure).

·       New-onset AF with no clear reversible cause.

·       Discharge Planning:

·       Ensure the patient is stable, anticoagulated appropriately (with follow-up arranged), and has a clear plan for outpatient management (e.g., rate control and anticoagulation).