Initial Management of Right Ventricular Conduction Delay

Initial Diagnostic Evaluation

• The American College of Cardiology recommends obtaining a 12-lead ECG to document the conduction pattern and screen for structural heart disease in patients with right bundle branch block (RBBB) 2
• A comprehensive assessment is necessary to determine if symptoms correlate with the conduction abnormality in patients with RBBB 3, 4

Key ECG Criteria for Complete RBBB

• The following ECG criteria are used to diagnose complete RBBB: QRS duration ≥120 ms, rsr', rsR', rSR, or rarely qR pattern in leads V1 or V2, S wave duration greater than R wave or >40 ms in leads I and V6, and normal R peak time in leads V5 and V6 but >50 ms in lead V1 2, 5

Risk Stratification Based on Clinical Presentation

• The American College of Cardiology recommends that permanent pacing should NOT be performed in asymptomatic patients with isolated RBBB and 1:1 atrioventricular conduction (Class III: Harm recommendation) 1
• Electrophysiology study (EPS) to measure HV interval is recommended in symptomatic patients with syncope and RBBB, and permanent pacing is warranted if HV interval ≥70 ms or evidence of infranodal block (Class I recommendation) 1

Screening for Underlying Structural Disease

• RBBB does not markedly increase the likelihood of underlying structural heart disease or left ventricular systolic dysfunction, unlike left bundle branch block 3, 4
• Echocardiography is recommended in patients with new onset RBBB in the setting of acute symptoms, associated symptoms suggesting heart failure, or concern for specific cardiomyopathies 2, 3, 5

Special Considerations

• The American College of Cardiology recommends that permanent pacing with defibrillator capability is reasonable in patients with Kearns-Sayre syndrome and any conduction disorder, including RBBB, if meaningful survival >1 year is expected (Class IIa) 1

Common Pitfalls to Avoid

• Permanent pacemakers should not be implanted in asymptomatic RBBB patients based solely on QRS duration, as this constitutes inappropriate therapy 1
• RBBB should not be assumed to indicate the same structural heart disease risk as LBBB, as the latter has a much stronger association with cardiomyopathy 3, 4
• Symptoms should be ensured to temporally correlate with documented bradycardia before attributing them to the conduction delay 3, 4