What are the next steps for a patient with a right bundle branch block (RBBB) seen on an electrocardiogram (EKG)?

Management of Right Bundle Branch Block on ECG

For isolated, asymptomatic RBBB with normal 1:1 atrioventricular conduction, observation only is recommended—no specific treatment is indicated and permanent pacing is contraindicated as it may cause harm. 1

Initial Clinical Assessment

The next steps depend critically on three factors: presence of symptoms (syncope, presyncope, lightheadedness), associated conduction abnormalities (bifascicular block, alternating bundle branch block), and suspicion for underlying cardiac disease. 1

Obtain Focused History for:

• Syncope or presyncope (indicates potential high-grade conduction disease requiring urgent evaluation) 1
• Lightheadedness or dizziness (warrants ambulatory ECG monitoring to establish symptom-rhythm correlation) 2, 1
• Family history of sudden cardiac death or cardiomyopathy 2
• Underlying neuromuscular disease (Kearns-Sayre syndrome, Anderson-Fabry disease, Emery-Dreifuss muscular dystrophy) 1
• Acute symptoms suggesting pulmonary embolism (chest pain, dyspnea, especially if RBBB is new-onset with QR pattern in V1) 3, 4

Diagnostic Workup Algorithm

For Asymptomatic Patients with Isolated RBBB:

• No further testing required beyond observation and regular follow-up 1
• Echocardiography may be considered if structural heart disease is suspected, though RBBB has lower association with structural disease compared to LBBB 2, 1
• Avoid unnecessary permanent pacing—this is explicitly contraindicated (Class III: Harm) 1

For Symptomatic Patients (Syncope/Presyncope):

• Urgent cardiology referral for electrophysiology study (EPS) to assess HV interval 1
• Permanent pacing is indicated if EPS demonstrates HV interval ≥70 ms or frank infranodal block 1
• Ambulatory ECG monitoring (24-48 hour Holter or event monitor) to document higher-degree AV block 2, 1

For Patients with Associated Conduction Abnormalities:

• Bifascicular block (RBBB + left anterior or posterior hemiblock): Requires cardiological work-up including exercise testing, 24-hour ECG, and imaging 2
• Alternating bundle branch block: Permanent pacing is mandated due to high risk of sudden complete heart block 1
• First-degree AV block with RBBB: Careful evaluation for progressive cardiac conduction disease 1

For Suspected Structural Heart Disease:

• Transthoracic echocardiography to evaluate for cardiomyopathy, valvular disease, congenital anomalies, or right ventricular abnormalities 2
• Advanced imaging (cardiac MRI, CT, or nuclear studies) if echocardiogram is unrevealing but suspicion remains high 2
• Stress testing with imaging may be considered if ischemic heart disease is suspected 2

Special Clinical Scenarios

Acute Presentation with New RBBB:

• Consider acute pulmonary embolism, especially if accompanied by S1Q3T3 pattern or QR pattern in V1—this has high positive predictive value for massive PE 3, 4, 5
• New RBBB during acute MI with first-degree AV block: Transcutaneous pacing is indicated (Class I recommendation) 1

Athletes:

• Complete RBBB is uncommon in athletes and warrants cardiological work-up including exercise testing, 24-hour ECG, and imaging to evaluate for underlying pathological causes such as arrhythmogenic right ventricular cardiomyopathy (ARVC) 2
• Obtain ECG in siblings if bifascicular block is present 2

Neuromuscular Disease:

• Kearns-Sayre syndrome: Permanent pacing with defibrillator capability is reasonable 1
• Anderson-Fabry disease with QRS >110 ms: Permanent pacing with defibrillator capability may be considered 1

Common Pitfalls to Avoid

• Do not assume all RBBB is benign—evaluate for underlying structural heart disease, especially when new-onset 1
• Do not place permanent pacemaker for isolated asymptomatic RBBB—this exposes patients to procedural risks and device complications without benefit 1
• Do not miss alternating bundle branch block—this mandates permanent pacing due to unstable conduction 1
• Do not overlook acute PE in patients with new RBBB, particularly with QR pattern in V1 3, 4
• Distinguish incomplete RBBB from pathological patterns such as Brugada type 2, right ventricular enlargement, ARVC, and atrial septal defect 6