What is the treatment approach for right bundle branch block (RBBB)?

Treatment Approach for Right Bundle Branch Block (RBBB)

Asymptomatic Right Bundle Branch Block (RBBB) generally requires no specific treatment, as it has a low risk of progression to high-degree AV block and good prognosis when isolated.

Evaluation and Diagnosis

• RBBB is characterized by:

  • rSR' configuration in right-oriented leads
  • QRS duration ≥0.12 seconds
  • Secondary ST-segment and T-wave changes in right precordial leads

• Initial evaluation should include:

  • 12-lead ECG to confirm RBBB pattern
  • Transthoracic echocardiogram to exclude structural heart disease
  • Assessment for underlying cardiac conditions (coronary artery disease, cardiomyopathy)

Treatment Algorithm

1. Asymptomatic RBBB

• No treatment required - permanent pacing is NOT indicated for asymptomatic RBBB 1
• Regular follow-up with clinical evaluation every 3-6 months and annual ECG is recommended for patients with bifascicular block (RBBB with left anterior fascicular block) and first-degree AV block 1
• Periodic ambulatory monitoring may be considered to detect asymptomatic conduction abnormalities in patients with bifascicular block 1

2. Symptomatic RBBB with Syncope or Presyncope

• Pacing is strongly indicated (Class I, Level B) in patients with:
  • Syncope + RBBB + positive electrophysiological study showing HV interval ≥70 ms 1
  • Syncope + RBBB + second/third-degree His-Purkinje block during incremental atrial pacing 1
  • Documented intermittent second or third-degree AV block 2

3. RBBB with Advanced Conduction Abnormalities

• Permanent pacemaker implantation is indicated for:
  • RBBB with intermittent second or third-degree AV block 2
  • RBBB with severe conduction disturbance below AV node (HV >100 ms or intra/infra-Hisian block during rapid atrial pacing) 2
  • Alternating bundle branch block (indicates disease in all three fascicles) 2

4. RBBB with Heart Failure

• Standard heart failure medications are recommended to attenuate adverse remodeling 1
• Cardiac resynchronization therapy may be considered in specific cases with reduced ejection fraction

Special Considerations

RBBB in Acute Settings

• In patients presenting with chest pain and RBBB:
  • ST-elevation is indicative of STEMI
  • ST-segment depression in lead I, aVL, and V5-6 is indicative of NSTE-ACS 2
  • More than 50% of patients presenting with acute chest pain and RBBB will ultimately have a diagnosis other than MI 2

Monitoring and Follow-up

• Only 1-2% of patients with asymptomatic bundle branch block progress to AV block per year 1
• Cardiac pacing has not been proven to reduce mortality in asymptomatic bundle branch block 1
• Patients with bifascicular block (RBBB + left anterior fascicular block) have a higher risk of progression to complete heart block compared to isolated RBBB 1

Prognosis

• Isolated RBBB generally has a good prognosis if asymptomatic 1
• RBBB with normal myocardial perfusion has good prognosis (annual cardiac death rate <1%) 1
• RBBB with perfusion defects has significantly worse prognosis (annual cardiac death rate ~6.4%) 1

Pitfalls and Caveats

• Do not confuse RBBB with other causes of wide QRS complex, especially ventricular tachycardia
• QRS width >0.14 seconds with RBBB pattern may suggest ventricular tachycardia rather than supraventricular tachycardia with aberrancy 2
• In patients with neuromuscular disease and any degree of fascicular block, cardiac pacing may be indicated due to unpredictable progression of AV conduction disease 2
• Calcium channel blockers should be used with extreme caution in broad complex tachycardias with RBBB pattern, as they may cause hemodynamic deterioration if the rhythm is ventricular tachycardia 3