Investigation for Atrial Fibrillation

Laboratory Studies

• CBC- Complete Blood Count (looking for anemia, infection)
• Electrolytes and BUN/creatinine levels (looking for electrolyte disturbances or renal failure)
• Cardiac enzymes - CK and/or troponin level (to investigate myocardial infarction as a primary or secondary event)
• May include a D-dimer if the patient has risk factors to merit a pulmonary embolism workup
• Thyroid function studies (looking for thyrotoxicosis)
• Digoxin level may be obtained when appropriate (to look for subtherapeutic levels and/or toxicity). It is generally considered safe to administer digoxin to a patient with atrial fibrillation on digoxin for rate control without waiting for a level to return from the laboratory when the patient presents with atrial fibrillation with rapid ventricular response (RVR).
• Toxicology testing or ethanol level – Acute intoxication

Imaging Studies

• Chest radiographic findings are usually normal. Look for radiographic evidence of CHF as well as signs of lung or vascular pathology (pulmonary embolism, pneumonia).
• If patients have a positive D-dimer result, they may require chest CT angiography to rule out pulmonary embolus.
• Echocardiography may be used to evaluate for valvular heart disease, left and right atrial size, left ventricular (LV) size and function, left ventricular hypertrophy (LVH), and pericardial disease.
• Transthoracic echocardiogram (TTE)
• Evaluate for valvular heart disease
• Evaluate atrial and ventricular chamber and wall dimensions
• Estimate ventricular function and evaluate for ventricular thrombi
• Estimate pulmonary systolic pressure (pulmonary hypertension)
• Evaluate for pericardial disease
• Transesophageal echocardiogram (TEE)
• Evaluate for left atrial (LA) thrombus (particularly in the LA appendage)
• Computed tomography (CT) or magnetic resonance imaging (MRI): If atrial fibrillation ablation is planned, then 3-dimensional imaging technologies (CT scan or MRI) are often helpful to evaluate atrial anatomy. Imaging data can be processed to create anatomic maps of the left atrium and pulmonary veins.

Other Tests

• Six-minute walk test or exercise test
• Six-minute walk or exercise testing can help assess the adequacy of rate control.
• Exercise testing can exclude ischemia prior to treatment of patients with Class Ic drugs and can be used to reproduce exercise-induced atrial fibrillation.
• Holter monitoring or event recording: Helpful to establish diagnosis and evaluate rate control.