What is the management approach for patients with Right Bundle Branch Block (RBBB)?

Management of Right Bundle Branch Block (RBBB)

For patients with isolated Right Bundle Branch Block (RBBB) and normal atrioventricular conduction, observation without permanent pacing is recommended in the absence of symptoms. 1

Assessment and Initial Evaluation

• A 12-lead ECG is essential to document rhythm, rate, and conduction patterns in patients with suspected RBBB 1
• RBBB is diagnosed by:
  • QRS duration ≥120 ms in adults
  • rSR' pattern in lead V1 and/or V2
  • S wave duration greater than R wave or >40 ms in leads I and V6
  • Normal R peak time in leads V5 and V6 but >50 ms in lead V1 1
• Incomplete RBBB has the same morphology but with QRS duration between 110-119 ms 1
• Transthoracic echocardiography is reasonable if structural heart disease is suspected 1

Risk Stratification

• Unlike LBBB, exercise-induced RBBB has not been associated with increased risk of death and cardiac events 1
• However, recent evidence suggests RBBB may not be entirely benign:
  • Patients with RBBB without known cardiovascular disease have increased risk of all-cause mortality and cardiovascular-related mortality 2
  • RBBB has been associated with increased risk of ischemic stroke, independent of other comorbidities 3

Management Algorithm

1. Symptomatic Patients

• For patients with syncope and RBBB:

  • If HV interval ≥70 ms or evidence of infranodal block on electrophysiology study (EPS), permanent pacing is recommended (Class I) 1
  • If symptoms suggest intermittent AV block, follow AV block diagnostic algorithm 1
  • EPS is reasonable in patients with symptoms suggestive of intermittent bradycardia with conduction system disease identified by ECG but no demonstrated AV block (Class IIa) 1

• For patients with alternating bundle branch block (QRS complexes with alternating LBBB and RBBB morphologies):

  • Permanent pacing is recommended (Class I) due to high risk of developing complete AV block 1

2. Asymptomatic Patients

• For asymptomatic patients with isolated RBBB and 1:1 AV conduction:

  • Permanent pacing is not indicated (Class III: Harm) 1
  • Observation is recommended 1

• For asymptomatic patients with extensive conduction system disease (bifascicular or trifascicular block):

  • Ambulatory electrocardiographic monitoring may be considered to document suspected higher degree of AV block (Class IIb) 1

3. Special Populations

• In patients with Kearns-Sayre syndrome and conduction disorders:

  • Permanent pacing is reasonable, with additional defibrillator capability if appropriate and meaningful survival >1 year is expected (Class IIa) 1

• In patients with Anderson-Fabry disease and QRS prolongation >110 ms:

  • Permanent pacing, with additional defibrillator capability if needed, may be considered if meaningful survival >1 year is expected (Class IIb) 1

Monitoring Considerations

• Cardiac rhythm monitoring is useful to establish correlation between heart rate/conduction abnormalities and symptoms 1
• The type of monitoring should be based on frequency and nature of symptoms:
  • 24-72 hour Holter monitoring for frequent symptoms
  • Event monitors or implantable loop recorders for infrequent symptoms 1

Pitfalls and Caveats

• RBBB with absent S waves in leads I and aVL may indicate concomitant LBB delay (bilateral bundle-branch delay), which carries higher risk 4
• RBBB can sometimes be mistaken for ventricular tachycardia, particularly in patients with congenital heart disease like Tetralogy of Fallot 1
• In patients with RBBB presenting with broad complex tachycardia without history of ischemic heart disease, calcium channel blockers may be effective, but caution is warranted as some patients may have ventricular tachycardia 5
• New-onset RBBB in the setting of acute myocardial infarction requires careful evaluation for potential development of complete heart block 1