From the Guidelines
Right Bundle Branch Block (RBBB) is a cardiac conduction abnormality that may not require specific treatment if asymptomatic, but underlying heart conditions should be evaluated and monitored. RBBB is characterized by a widened QRS complex (greater than 120 milliseconds) with a distinctive RSR' pattern in lead V1 and a wide S wave in leads I and V6. According to the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1, patients with RBBB or intraventricular conduction delay on ECG also have increased risk of left ventricular systolic dysfunction compared with those with completely normal ECGs.
Key Considerations
- Echocardiography can identify various structural cardiac abnormalities underlying conduction disturbance, including cardiomyopathy, valvular heart disease, congenital anomalies, tumors, infections, infiltrative processes, immunologically mediated conditions, and diseases of the great vessels and pericardium 1.
- An EPS may provide acute diagnostic information, avoiding the potential risks of delayed diagnosis with outpatient monitoring strategies, but has variable sensitivity depending on the presentation and does impart a small procedural risk 1.
- In patients with RBBB, echocardiography is recommended to evaluate for underlying heart conditions, and further cardiac evaluation including stress testing may be warranted if symptoms like syncope are present.
Evaluation and Management
- Ambulatory electrocardiographic monitoring can be used to document clinically significant arrhythmias in asymptomatic patients as well 1.
- Cardiac MRI may be considered in selected patients with LBBB and normal left ventricular function by echocardiography where sarcoidosis, connective tissue disease, myocarditis, or other dilated cardiomyopathies are suspected on clinical grounds 1.
- Regular cardiac follow-up is recommended to monitor for any progression of conduction disease.
Clinical Context
- The significance of RBBB varies depending on the clinical context - it can be benign in healthy individuals but may indicate increased risk in those with existing heart disease.
- In patients with syncope and RBBB, permanent pacing has been recommended for those with HV intervals ≥70 ms or frank infranodal block 1.
From the Research
Definition and Prevalence of RBBB
- Right bundle branch block (RBBB) is a common electrocardiographic abnormality, with a prevalence of 8% in the general population without cardiovascular events 2.
- RBBB can be complete (cRBBB) or incomplete (iRBBB), with cRBBB being associated with an increased risk of all-cause mortality and cardiovascular events 2.
Association with Cardiovascular Morbidity and Mortality
- Complete RBBB (cRBBB) is associated with an increased risk of cardiovascular morbidity and mortality, including heart failure and chronic kidney disease 2, 3.
- The presence of RBBB in patients with anterior wall ST-segment elevation myocardial infarction (AW-STEMI) is a significant independent predictor of poor prognosis, including higher rates of acute heart failure, complete heart block, and 30-day in-hospital mortality 3.
Diagnosis and Differentiation
- Incomplete RBBB (iRBBB) can be challenging to diagnose and differentiate from other electrocardiographic patterns, such as type-2 Brugada ECG pattern, right ventricular enlargement, and arrhythmogenic right ventricular cardiomyopathy 4.
- The presence of a QR pattern in V1 on the electrocardiogram (ECG) has a high positive predictive value for diagnosing cardiac arrest caused by high-risk pulmonary embolism 5.
Treatment and Management
- Cardiac resynchronization therapy (CRT) can be used to improve ventricular function and heart failure in patients with RBBB and congenital heart disease 6.
- Targeted resynchronization in systemic and subpulmonary right ventricles can be used to improve ventricular function and heart failure in patients with RBBB 6.