What is the significance of a right bundle branch block (RBBB)?

From the Guidelines

Right bundle branch block (RBBB) is a significant finding that requires comprehensive cardiac evaluation, including echocardiography, to assess for underlying structural heart disease, as it can be a marker of conditions such as coronary artery disease, cardiomyopathy, or pulmonary hypertension 1. The significance of RBBB varies depending on whether it occurs in isolation or with other cardiac conditions. Isolated RBBB in an otherwise healthy person is generally considered benign and doesn't require specific treatment. However, RBBB can be a marker of underlying heart disease.

Key Points to Consider

• RBBB can develop after cardiac surgery or procedures, and its presence is a strong independent predictor for pacemaker implantation after transcatheter aortic valve replacement (TAVR) 2.
• Patients with RBBB should undergo a comprehensive cardiac evaluation, including echocardiography to assess for structural heart disease, as the presence of RBBB on ECG increases the likelihood of left ventricular systolic dysfunction being diagnosed by echocardiogram 1.
• No specific medications are needed for isolated RBBB, but treatment focuses on any underlying conditions.
• Regular cardiac follow-up is recommended, particularly if the RBBB is new or associated with symptoms like shortness of breath, chest pain, or syncope.

Diagnostic Approach

• Electrocardiography is the primary method of diagnosing potential conduction disorders, and recording duration may vary from a 10-second ECG to continuous ambulatory recordings 1.
• Ambulatory electrocardiographic monitoring can be used to document clinically significant arrhythmias in asymptomatic patients, and most current monitoring systems will automatically store clinically abnormal rhythms in addition to patient-triggered recordings 1.

From the Research

Significance of Right Bundle Branch Block

• The presence of right bundle branch block (RBBB) with 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 3.
• RBBB is associated with more severe and extensive left ventricular myocardial damage, as well as more severe coronary artery disease (CAD) 4.
• However, other studies suggest that RBBB is not a predictor of coronary artery disease 5.
• In patients with suspected myocardial infarction, RBBB is considered a high-risk factor for mortality, but it may not be a trigger for acute angiography 6.
• RBBB is a pattern seen on the 12-lead ECG, resulting from interrupted normal electrical activity in the His-Purkinje system, and is often regarded as benign 7.

Clinical Implications

• The presence of RBBB with a QR pattern in V1 on ECG can be an independent predictor for high-risk pulmonary embolism patients who may require advanced treatments, including systemic thrombolysis or invasive embolectomy 3.
• Patients with RBBB and CAD may have more severe left ventricular wall asynergy and higher end-diastolic left ventricular pressure 4.
• The relationship between RBBB and the presence and severity of CAD is unclear, and further studies are needed to establish this association 5.
• RBBB may be associated with a higher mortality rate in patients with suspected myocardial infarction, but its role as a trigger for acute angiography is still debated 6.

ECG Findings and Diagnosis

• RBBB is characterized by a widened QRS complex and changes in the directional vectors of the R and S waves on the 12-lead ECG 7.
• The ECG findings of RBBB can be used to diagnose cardiac arrest caused by high-risk pulmonary embolism, and to identify patients who may require advanced treatments 3.
• The differential diagnosis of RBBB on ECG includes other conditions that can cause a widened QRS complex, such as left bundle branch block and ventricular tachycardia 7.