What is the management approach for a patient with right bundle branch block?

Management of Right Bundle Branch Block (RBBB)

The management of right bundle branch block (RBBB) should focus on identifying underlying causes and assessing risk of progression to higher-degree conduction disorders, with permanent pacing recommended only for specific high-risk presentations such as syncope with HV interval ≥70ms or alternating bundle branch block.

Definition and Prevalence

• RBBB is characterized by QRS duration ≥120 ms in adults, an rSR' pattern in leads V1-V2, and S waves of greater duration than R waves in leads I and V6 1
• RBBB is detected in approximately 1-2.5% of the general population and may be an isolated finding or associated with underlying cardiovascular disorders 1

Initial Evaluation

Clinical Assessment

• Evaluate for symptoms such as syncope, presyncope, dizziness, fatigue, or exercise intolerance, which may indicate more significant conduction system disease 1
• Assess for risk factors of structural heart disease or pulmonary embolism, as RBBB may be associated with these conditions 2
• Document the presence of any bifascicular block (RBBB plus left anterior or posterior fascicular block), which carries a higher risk of progression to complete heart block 3, 1

Diagnostic Testing

• In patients with newly detected LBBB, a transthoracic echocardiogram is recommended to exclude structural heart disease (Class I recommendation) 3
• For RBBB, transthoracic echocardiography is reasonable if structural heart disease is suspected 3
• In symptomatic patients with conduction system disease where atrioventricular block is suspected, ambulatory electrocardiographic monitoring is useful (Class I recommendation) 3

Management Algorithm Based on Clinical Presentation

Asymptomatic RBBB

• In asymptomatic patients with isolated RBBB and normal 1:1 atrioventricular conduction, permanent pacing is not indicated (Class III: Harm recommendation) 3
• Regular follow-up with ECG monitoring is recommended to assess for progression of conduction disease 1

RBBB with Syncope or Presyncope

• In patients with syncope and bundle branch block who have an HV interval ≥70 ms or evidence of infranodal block on electrophysiology study, permanent pacing is recommended (Class I recommendation) 3
• Ambulatory electrocardiographic monitoring should be used to document clinically significant arrhythmias in these patients 3
• The presence of bundle branch block in a patient with syncope is a predictor for abnormal conduction properties identified at electrophysiology study 3

RBBB with Specific High-Risk Features

• In patients with alternating bundle branch block (QRS complexes with alternating LBBB and RBBB morphologies), permanent pacing is recommended (Class I recommendation) 3
• For patients with Kearns-Sayre syndrome and conduction disorders, permanent pacing is reasonable, with additional defibrillator capability if appropriate 3
• In patients with Anderson-Fabry disease and QRS prolongation >110 ms, permanent pacing may be considered 3

Special Considerations

Bifascicular Block

• Patients with bifascicular block (RBBB plus left anterior or posterior fascicular block) are at higher risk for progression to complete heart block 3, 1
• The prognostic value of the HV interval is significant - progression rate to AV block at 4 years was 4%, 2%, and 12% for patients with HV intervals of <55 ms, 55-69 ms, and ≥70 ms respectively 3
• Patients with an HV interval of 100 ms have an even higher progression rate of 24% 3

Medication Considerations

• Certain medications are contraindicated in patients with RBBB plus left hemiblock (bifascicular block):
  • Flecainide is contraindicated in patients with RBBB when associated with a left hemiblock, unless a pacemaker is present 4
  • Flecainide can slow cardiac conduction and produce dose-related increases in PR, QRS, and QT intervals 4
• Be cautious with medications that may further impair cardiac conduction in patients with RBBB 1

RBBB and Brugada Syndrome

• RBBB with ST-segment elevation in leads V1-V3 may indicate Brugada syndrome, which is associated with risk of sudden death 5
• Patients with this ECG pattern should be referred for specialized cardiac evaluation, as implantable defibrillators may be indicated 5

Follow-up Recommendations

• Regular ECG monitoring is recommended to assess for changes in conduction patterns or QRS duration 1
• Watch for symptoms of worsening cardiac conduction, including dizziness, syncope, or palpitations 1
• In patients with bifascicular block, closer monitoring is warranted due to the higher risk of progression to complete heart block 3, 1

Prognosis

• Isolated RBBB without structural heart disease generally has a good prognosis 6
• In a follow-up study of RBBB patients, 94% had no evidence of cardiovascular disease at initial diagnosis, and only 6% developed new cases of coronary heart disease during follow-up 6
• Progressive electrical dysfunction in the form of complete heart block is rare in isolated RBBB 6