What to do when an electrocardiogram (EKG) shows right bundle branch block (RBBB) in a patient?

Management of Right Bundle Branch Block (RBBB) on EKG

In patients with newly detected right bundle branch block (RBBB) on EKG, no specific intervention is required if the patient is asymptomatic and has no evidence of underlying structural heart disease. 1

Initial Evaluation

When RBBB is detected on EKG, the following evaluation should be performed:

1. Assess for symptoms:

   • Lightheadedness, syncope, or presyncope
   • Chest pain
   • Shortness of breath
   • Palpitations

2. Targeted cardiac evaluation:

   • Complete 12-lead ECG to document rhythm, rate, and conduction patterns
   • Evaluate for coexisting conduction abnormalities (left anterior/posterior fascicular block)
   • Check for signs of myocardial ischemia or infarction

3. Further testing based on clinical presentation:

   • If asymptomatic with isolated RBBB: No further testing is typically required
   • If symptomatic or with concerning features: Proceed with additional evaluation

Additional Evaluation for Symptomatic Patients

For patients with RBBB who are symptomatic or have concerning features:

• Transthoracic echocardiography: Reasonable if structural heart disease is suspected 1
• Ambulatory electrocardiographic monitoring: Useful when symptoms suggest intermittent bradycardia or higher-degree AV block 1
• Exercise stress testing: To evaluate for ischemic heart disease and to assess for exercise-induced conduction abnormalities 1
• Electrophysiological study (EPS): Consider in patients with symptoms suggestive of intermittent bradycardia with no demonstrated AV block on monitoring 1

Special Considerations

RBBB with Bifascicular or Trifascicular Block

In patients with RBBB plus left anterior or posterior fascicular block (bifascicular block):

• Higher risk of progression to complete heart block
• Consider ambulatory ECG monitoring to document suspected higher-degree AV block 1
• More intensive evaluation is warranted

RBBB in Specific Clinical Scenarios

• RBBB with chest pain: Consider acute myocardial infarction, particularly septal infarction, even if RBBB is the only ECG finding 2
• RBBB with pulmonary symptoms: Consider pulmonary embolism, especially if there is a QR pattern in V1 3
• RBBB in athletes: Complete cardiac evaluation with history, physical examination, ECG, echocardiogram, and stress test is recommended 1

Indications for Pacemaker Implantation

Permanent pacing is indicated in the following scenarios:

• Alternating bundle branch block (RBBB and LBBB on successive ECGs): Permanent pacing is recommended even without symptoms 1
• RBBB with syncope and positive EPS (HV interval ≥70 ms or higher-degree His-Purkinje block): Permanent pacing is indicated 1
• RBBB with symptoms and documented intermittent high-degree AV block: Permanent pacing is indicated 1

Permanent pacing is NOT indicated in:

• Asymptomatic patients with isolated RBBB and normal AV conduction 1

Follow-up Recommendations

• Asymptomatic patients with isolated RBBB: No specific follow-up required
• RBBB with bifascicular block: Consider periodic follow-up with ECG to assess for progression
• RBBB with symptoms: Follow-up based on underlying etiology and symptom resolution

Important Caveats

• Unlike LBBB, isolated RBBB is not typically associated with left ventricular systolic dysfunction 4
• QRS duration and axis deviation in RBBB do not reliably predict left ventricular function 4
• RBBB may be the first manifestation of underlying cardiac or pulmonary disease, so careful evaluation is warranted in the appropriate clinical context
• RBBB pattern during right ventricular pacing may indicate lead perforation or malposition and should prompt immediate evaluation 5