Investigations & potential roles
Chest radiography
Exclude concomitant lung disease, heart failure, baseline in patients receiving amiodarone.
Ambulatory electrocardiography (Holter monitor, event monitor, loop monitor)
Document AF, exclude alternative diagnosis (atrial tachycardia, atrial flutter, AVNRT/AVRT, ventricular tachycardia), symptom–rhythm correlation, assess ventricular rate control.
Treadmill exercise test
Investigation of patients with symptoms of coronary artery disease, assessment of rate control.
Transesophageal echocardiography
Rule out left atrial appendage thrombus, facilitate cardioversion in patients not receiving oral anticoagulation, more precise characterization of structural heart disease (mitral valve disease, atrial septal defects, cortriatriatum, etc).
Electrophysiological study
Patients with documented regular supraventricular tachycardia (ie, atrial tachycardia, AVNRT/AVRT, atrial flutter) that is amenable to catheter ablation.
Serum calcium and magnesium
In cases of suspected deficiency (ie, diuretic use, gastrointestinal losses), which could influence therapy (ie, sotalol.)
Sleep study (ambulatory oximetry or polysomnography)
In patients with symptoms of obstructive sleep apnea or in select patients with advanced symptomatic heart failure.
Ambulatory blood pressure monitoring
In cases of borderline hypertension.
Genetic testing
In rare cases of apparent familial AF (particularly with onset at a young age) with additional features of conduction disease, Brugada syndrome, or cardiomyopathy.

AVNRT/AVRT, atrioventricular nodal reentrant tachycardia/atrioventricular reentrant tachycardia.