What is the appropriate work‑up for a patient with suspected atrial fibrillation?

Workup for Atrial Fibrillation

The workup for atrial fibrillation requires immediate 12-lead ECG documentation, followed by a structured evaluation including detailed history, physical examination, transthoracic echocardiography, and laboratory testing (electrolytes, thyroid function, renal/hepatic function, and complete blood count), with stroke risk assessment using CHA₂DS₂-VASc scoring to guide anticoagulation decisions. 1, 2

Immediate Assessment

Hemodynamic Stability First

• Assess for hypotension, altered mental status, chest pain, acute heart failure, or signs of shock requiring immediate electrical cardioversion 2
• Document vital signs including heart rate, blood pressure, respiratory rate, and oxygen saturation 2
• Evaluate for syncope, presyncope, or severe symptoms requiring urgent intervention 2

ECG Documentation

• Obtain 12-lead ECG immediately to confirm the diagnosis and identify signs of structural heart disease (myocardial infarction, LV hypertrophy, bundle branch block, ventricular pre-excitation, cardiomyopathy, or ischemia) 3, 1, 2
• If arrhythmia not captured on initial ECG, use 24-hour Holter monitor for frequent episodes or event recorder for infrequent episodes 1, 4

Essential History

Symptom Characterization

• Assess symptom severity using EHRA score (European Heart Rhythm Association classification) 3, 1
• Document palpitations, chest pain, dyspnea, fatigue, lightheadedness, or syncope 1, 4
• Determine if rhythm feels regular or irregular during episodes 3
• Identify precipitating factors: exercise, emotion, alcohol intake, caffeine, stress, or medications 3, 4
• Establish frequency, duration, and timing of episodes (nocturnal episodes suggest vagally-mediated AF; daytime episodes during activity suggest adrenergically-mediated AF) 3, 4

Establish AF Duration and Type

• Determine time of onset to classify as: first diagnosed, paroxysmal (self-terminating within 7 days), persistent (>7 days or requiring cardioversion), long-standing persistent (≥1 year), or permanent 3, 1
• The 48-hour time point is clinically critical—after this, spontaneous conversion likelihood is low and anticoagulation must be considered 3

Comorbidity Assessment

• History of hypertension, coronary heart disease, heart failure, peripheral vascular disease, cerebrovascular disease, stroke, diabetes, or chronic pulmonary disease 3
• Alcohol abuse habits 3
• Family history of AF 3

Physical Examination

Cardiac Findings

• Irregular pulse, irregular jugular venous pulsations, variation in first heart sound intensity, or absence of fourth heart sound previously heard during sinus rhythm 1
• Signs of valvular heart disease, myocardial abnormalities, or heart failure 1
• Elevated jugular venous pressure, pulmonary rales, or peripheral edema suggesting congestive heart failure 4

Laboratory Testing

Essential Labs

• Serum electrolytes (potassium, magnesium) 1, 2
• Thyroid function tests (TSH, free T4) 1, 2, 5
• Renal function (creatinine, eGFR) 1, 2
• Hepatic function 1, 2
• Complete blood count 1, 2, 4

Imaging

Transthoracic Echocardiography

• Perform in all patients to detect structural heart disease, assess LV and valvular function, evaluate right ventricular pressure, and measure atrial size 3, 1, 2, 5
• Urgent echocardiogram required for hemodynamically compromised patients 3
• Transthoracic echo cannot exclude thrombus in the left atrial appendage 3

Transesophageal Echocardiography (TOE)

• Consider if AF duration >48 hours or duration uncertain and cardioversion planned, to rule out intracardiac thrombus 3
• May be difficult in patients in acute distress and may not be available in emergency settings 3

Stroke Risk Assessment

CHA₂DS₂-VASc Scoring

• Calculate stroke risk using validated CHA₂DS₂-VASc score to guide anticoagulation decisions 1, 4, 5
• Anticoagulation recommended for estimated stroke risk ≥2% per year 6

Common Pitfalls to Avoid

• Do not delay anticoagulation assessment when AF duration exceeds 48 hours due to increased thromboembolism risk 1, 2
• Do not fail to distinguish ventricular tachycardia from supraventricular tachycardia with aberrancy, as this leads to inappropriate treatment 2, 4
• Do not dismiss complex ventricular ectopy in elderly patients as benign without appropriate evaluation 2, 4
• Do not normalize heart rate in compensatory tachycardias when cardiac function is poor, as cardiac output can be dependent on rapid heart rate 4

Immediate Referral Indications

• Immediate cardiology referral if palpitations associated with syncope, presyncope, or chest pain 2, 4
• Heart rate >150 bpm with symptoms of instability (acute altered mental status, ischemic chest discomfort, acute heart failure, hypotension, or shock) 4
• Hemodynamically unstable patients including those with decompensated heart failure 5