What is the diagnosis and treatment for Right Bundle Branch Block (RBBB)?

From the Guidelines

Patients with RBBB should undergo a thorough cardiac evaluation to determine if there's an underlying heart condition causing the RBBB, but generally do not require specific treatment if asymptomatic. RBBB stands for Right Bundle Branch Block, which is a cardiac conduction abnormality where electrical impulses are delayed or blocked as they travel through the right bundle branch of the heart. This condition is often discovered incidentally on an electrocardiogram (ECG) and may not require specific treatment if you're asymptomatic, as several studies from the 1970s demonstrated no benefit from prophylactic pacing in asymptomatic patients with conduction disorders, including RBBB 1.

Key Considerations

• The diagnosis is made when an ECG shows a QRS complex duration of 120 milliseconds or greater, with specific patterns in leads V1 and V6.
• While isolated RBBB in an otherwise healthy person generally has a good prognosis, it's worth monitoring with regular check-ups as it can sometimes indicate progressive cardiac disease.
• If you have RBBB along with symptoms like shortness of breath, fatigue, or chest pain, these symptoms would be treated based on the underlying cause rather than the RBBB itself.
• Certain conditions, such as Kearns-Sayre syndrome or Anderson Fabry disease, may have a high incidence of atrioventricular block and sudden cardiac death, and may require more aggressive management, including permanent pacing 1.

Management Approach

• According to the 2018 ACC/AHA/HRS guideline, patients with RBBB and high-risk features, such as syncope or alternating BBB, should receive a pacemaker, as they are at high risk of developing complete atrioventricular block 1.
• For patients with LVEF 36-50%, LBBB, QRS >150 ms, and Class II or greater HF symptoms, cardiac resynchronization therapy (CRT) may be considered, as it has been shown to improve clinical and echocardiographic responses in these patients 1.

From the Research

RBBB Overview

• RBBB stands for Right Bundle Branch Block, a condition where there is a blockage in the right bundle branch of the heart's electrical conduction system 2, 3.
• The presence of RBBB can be associated with coronary artery disease (CAD), but its prognostic implication is unclear 3.

Relationship with Coronary Artery Disease

• A study found that patients with RBBB and CAD did not differ significantly from those with CAD without conduction disturbances in terms of age, New York Heart Association functional class, or incidence of previous myocardial infarction 2.
• However, another study suggested that RBBB is not a predictor of coronary artery disease, and there was no significant association between the presence of RBBB and the magnitude of Gensini score 3.
• A more recent study found that RBBB or bifascicular block does not appear to offer any clinical utility when evaluating patients with suspected acute myocardial infarction 4.

Clinical Outcomes

• Patients with RBBB and acute myocardial infarction may have worse prognosis compared to those with isolated ST segment elevation 5.
• However, after multivariate adjustment, mortality was similar in patients with left bundle branch block and lower in patients with right bundle branch block, respectively, when compared to ST segment elevation 5.
• The presence of RBBB with concomitant ST-elevation was associated with increased mortality 5.

Comparison with Left Bundle Branch Block

• Left bundle branch block (LBBB) is associated with more severe left ventricular dysfunction and worse clinical outcomes compared to RBBB 6, 5.
• Patients with LBBB had a higher frequency of congestive heart failure, cardiomegaly, and impaired left ventricular function compared to those with RBBB 6.