From the Guidelines
RBBB is a cardiac conduction abnormality that may not require specific treatment if asymptomatic, but further cardiac evaluation is recommended to rule out underlying heart conditions, especially if risk factors or symptoms are present, as suggested by the 2019 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1.
Definition and Diagnosis
RBBB stands for Right Bundle Branch Block, a condition where electrical impulses are delayed or blocked as they travel through the right bundle branch of the heart. It is often found incidentally on an electrocardiogram (ECG) and appears as a widened QRS complex (greater than 120 milliseconds) with a characteristic RSR' pattern in the right precordial leads (V1-V3).
Clinical Significance
The presence of RBBB itself doesn't typically require medication unless there's an associated condition. However, patients with RBBB may be at risk for underlying heart conditions, such as coronary artery disease, heart failure, pulmonary embolism, or congenital heart defects. According to the 2021 ESC guidelines for the management of acute coronary syndromes, patients with RBBB presenting with chest pain should undergo further evaluation, including hs-cTn T/I measurement at presentation, to rule out myocardial infarction 2.
Management
Further cardiac evaluation, such as an echocardiogram, stress test, or other cardiac imaging, is recommended to rule out underlying heart conditions, especially if risk factors or symptoms are present 1. In patients with syncope and RBBB, an electrophysiological study (EPS) can be used to evaluate atrioventricular conduction and identify the presence and extent of infranodal disease, and permanent pacing may be recommended for patients with syncope and HV intervals ≥70 ms or frank infranodal block 1.
From the Research
Definition and Prevalence of RBBB
- RBBB occurs in 0.2% to 1.3% of people and is considered a benign finding 3
- However, some studies have suggested increased risk of cardiovascular morbidity and mortality 3, 4
Association with Cardiovascular Disease
- RBBB is associated with increased risk of all-cause mortality, cardiovascular-related mortality, and lower exercise tolerance in patients without prior diagnosis of cardiovascular disease 3
- RBBB is considered a marker of early cardiovascular disease and merits further prospective evaluation 3
- In patients with suspected acute coronary syndromes, RBBB is associated with elevated mortality and may require immediate transfer to the cardiac catheterization laboratory 4
Electrocardiographic Features
- Typical electrocardiographic appearances of RBBB include prolongation > 0.12 s of the QRS complex, RR' or rR' or Rr' appearances in V1, and widened S waves in the leads exploring the left ventricle 5
- A delay in the appearance of the intrinsic deflection > 0.08 s may also be observed in the right precordial leads, and negative T waves with ST depression may be seen in V1 and sometimes in V2 5
Site of Block within the Right Bundle
- Conduction disturbance in the peripheral portion of the right bundle branch is observed in 80.5% of cases, suggesting that peripheral block is much more common than proximal block in adults 6
- The site of block within the right bundle can be divided into four groups: proximal block, peripheral block, diffuse block, and non-specific block 6