Treatment of Right Bundle Branch Block (RBBB)
Asymptomatic isolated RBBB requires no treatment—observation only is recommended, as permanent pacing is contraindicated and may cause harm. 1, 2
Initial Assessment and Risk Stratification
Determine symptom status and associated conduction abnormalities:
- Obtain 12-lead ECG to confirm RBBB (QRS ≥120 ms, rSR' pattern in V1-V2, S waves greater than R waves in leads I and V6) and identify additional conduction disorders 1, 3
- Assess specifically for syncope, presyncope, lightheadedness, dizziness, fatigue, or exercise intolerance 1, 3
- Perform transthoracic echocardiography if structural heart disease is suspected, particularly in symptomatic patients 4, 1
- Note that RBBB is less commonly associated with structural disease compared to LBBB 4, 2
Treatment Algorithm Based on Clinical Presentation
Asymptomatic Isolated RBBB (Most Common Scenario)
No treatment is indicated—this is a Class III (Harm) recommendation for permanent pacing. 1, 2
- Regular follow-up with ECG monitoring to detect progression to more complex conduction disorders 1, 2
- Isolated RBBB without symptoms or other cardiac abnormalities is generally benign 2
Symptomatic RBBB or RBBB with Additional Conduction Abnormalities
For patients with syncope:
- Obtain ambulatory ECG monitoring (24-hour to 14-day duration) to establish symptom-rhythm correlation and detect intermittent higher-degree AV block 4, 1, 3
- Proceed to electrophysiology study (EPS) to measure HV interval if other testing is unrevealing 1, 3
- Permanent pacing is definitively indicated (Class I) if EPS demonstrates HV interval ≥70 ms or evidence of infranodal block 1, 3, 2
For RBBB with bifascicular block (left anterior or posterior hemiblock):
- Careful evaluation for progressive cardiac conduction disease is required 1, 3
- Consider electrophysiologic study to evaluate atrioventricular conduction 3
- ECG screening of siblings is recommended if bifascicular block is present in a young athlete 3
For alternating bundle branch block:
Special Clinical Scenarios
Acute myocardial infarction with new RBBB and first-degree AV block:
- Transcutaneous pacing capability should be available (Class I recommendation) 3, 2
- Temporary transvenous pacing may be considered (Class IIb) 3, 2
Neuromuscular diseases:
- Permanent pacing is reasonable (Class IIa) for Kearns-Sayre syndrome with conduction disorders 3, 2
- Permanent pacing may be considered (Class IIb) for Anderson-Fabry disease with QRS >110 ms 3, 2
Heart failure with RBBB:
- Patients with non-LBBB QRS morphology, including RBBB, may not derive significant benefit from cardiac resynchronization therapy (CRT) 3
- However, those demonstrating left ventricular mechanical dyssynchrony by speckle-tracking radial strain or interventricular mechanical delay may benefit from CRT 3
Advanced Imaging Considerations
When to pursue cardiac MRI:
- Obtain cardiac MRI in selected patients when sarcoidosis, connective tissue disease, myocarditis, or other infiltrative cardiomyopathies are suspected clinically, even with normal echocardiography 3
- Studies show cardiac MRI detects subclinical abnormalities in 33-42% of patients with conduction disease and normal echocardiograms 3
Critical Pitfalls to Avoid
Do not pace asymptomatic isolated RBBB:
- This is explicitly contraindicated (Class III: Harm) due to lack of benefit and exposure to procedural risks and device complications 2
Do not misdiagnose ventricular tachycardia as SVT with RBBB aberrancy:
- This is especially dangerous in patients with structural heart disease 1
Do not assume all RBBB patterns are benign: