What is the most appropriate initial imaging test to evaluate a patient with atrial fibrillation?

• A. Chest X-ray
• B. Transesophageal echocardiography
• C. Transthoracic echocardiography
• D. Coronary angiography

Answer: (C)

When evaluating atrial fibrillation, you first want to look for structural heart problems that may underlie the rhythm abnormality and influence treatment. Transthoracic echocardiography fits that need best as an initial study because it is noninvasive, rapid, and provides essential information about the heart’s structure and function. It can quantify left ventricular systolic function, reveal wall-motion abnormalities that suggest ischemic disease, assess the presence and amount of valvular disease (such as mitral stenosis or regurgitation) that can contribute to AF, and measure left atrial size. Left atrial enlargement, in particular, often accompanies AF and has implications for stroke risk and management decisions, including rhythm control strategies and anticoagulation planning.

Chest X-ray offers limited detail about cardiac function and valvular pathology, so it’s not the best choice for a comprehensive initial assessment. Transesophageal echocardiography provides superior visualization of the left atrial appendage and can detect thrombus or detailed valvular pathology, but it is semi-invasive and typically reserved for specific situations, such as before cardioversion when there is concern for thrombus or when plan involves procedures like ablation. Coronary angiography is targeted toward evaluating coronary arteries and is not the first-line imaging test for evaluating AF itself.