Atrial Fibrillation with Transient Left Bundle Branch Block

Underlying Cardiovascular Disease

• The European Society of Cardiology suggests that coronary artery disease is a common underlying etiology in older adults with atrial fibrillation and transient left bundle branch block, with coronary ischemia causing transient conduction disturbances 1, 2
• The American College of Cardiology recommends considering hypertension, particularly with left ventricular hypertrophy, as a strong association with both atrial fibrillation and conduction abnormalities 1, 2, 4
• The European Heart Journal notes that atrial fibrosis develops through activation of the renin-angiotensin-aldosterone system in the setting of coronary artery disease and hypertension, predisposing to atrial fibrillation development 3

Evaluation and Management

• The European Heart Journal advises that the combination of new-onset atrial fibrillation with conduction abnormalities in the setting of acute myocardial infarction portends a particularly poor prognosis, and mandates evaluation for acute coronary ischemia 1, 2, 3
• The American College of Cardiology recommends performing transthoracic echocardiography to assess for structural heart disease, left ventricular dysfunction, and valvular abnormalities in patients with atrial fibrillation and transient left bundle branch block 5
• The European Society of Cardiology suggests considering coronary angiography or stress testing to exclude obstructive coronary artery disease, particularly if chest pain or ischemic symptoms are present 1, 2