Follow-Up Tests After Diagnosis of Bundle Branch Block (BBB)
For patients with newly detected bundle branch block (BBB), a comprehensive evaluation should be performed including transthoracic echocardiography, ambulatory electrocardiographic monitoring if symptomatic, and consideration of advanced imaging or electrophysiological studies based on specific clinical scenarios. 1
Initial Evaluation
Left Bundle Branch Block (LBBB)
- Transthoracic echocardiography is recommended for all patients with newly detected LBBB to exclude structural heart disease 1
- In patients with LBBB where structural heart disease is suspected but echocardiogram is unrevealing, advanced imaging (cardiac MRI, CT, or nuclear studies) is reasonable 1
- In selected asymptomatic patients with LBBB in whom ischemic heart disease is suspected, stress testing with imaging may be considered 1
Right Bundle Branch Block (RBBB) and Other Conduction Disorders
- Transthoracic echocardiography is reasonable in patients with intraventricular conduction disorders other than LBBB if structural heart disease is suspected 1
- RBBB is generally associated with lower risk compared to LBBB but should still be evaluated for underlying cardiac pathology 1
Follow-Up for Symptomatic Patients
- In symptomatic patients with conduction system disease where atrioventricular block is suspected, ambulatory electrocardiographic monitoring is useful 1
- For patients with symptoms suggestive of intermittent bradycardia (lightheadedness, syncope) with conduction system disease identified by ECG and no demonstrated atrioventricular block, electrophysiological study (EPS) is reasonable 1
- In patients with syncope and bundle branch block who are found to have an HV interval ≥70 ms or evidence of infranodal block at EPS, permanent pacing is recommended 1
Follow-Up for Asymptomatic Patients
- In selected asymptomatic patients with extensive conduction system disease (bifascicular or trifascicular block), ambulatory electrocardiographic recording may be considered to document suspected higher degree of atrioventricular block 1
- Asymptomatic patients with isolated conduction disease and 1:1 atrioventricular conduction do not require permanent pacing 1
- Regular follow-up is important as LBBB is associated with increased risk of developing heart failure and cardiovascular mortality even in asymptomatic patients with normal left ventricular function 2, 3
Special Considerations
Specific Patient Populations
- In patients with alternating bundle branch block, permanent pacing is recommended 1
- In patients with neuromuscular diseases and BBB, additional evaluation and potential permanent pacing should be considered 1
- In athletes with BBB, a cardiological work-up including exercise testing, 24-hour ECG, and imaging is recommended to evaluate for underlying pathological causes 1
Genetic Considerations
- ECG screening should be considered for siblings of young patients with bifascicular block patterns 1
- In patients with lamin A/C gene mutations and LBBB, permanent pacing with additional defibrillator capability may be reasonable 1
Monitoring and Long-term Follow-up
- Regular clinical and ECG follow-up is recommended for all patients with BBB, with frequency determined by the presence of symptoms and underlying heart disease 1
- Patients with LBBB should be monitored for development of heart failure, as LBBB is associated with a 2.85-fold increased risk of new-onset heart failure even in previously asymptomatic individuals 2
- Long-term follow-up is particularly important for patients with LBBB, as it carries a higher risk of progression to cardiovascular events compared to RBBB 4, 3
Pitfalls and Caveats
- Do not assume all BBB patterns are benign, especially LBBB, which is more strongly associated with underlying structural heart disease 1
- Avoid missing intermittent or rate-dependent BBB by using appropriate duration of ambulatory monitoring 1
- Remember that LBBB can interfere with the interpretation of stress tests for ischemia detection, requiring imaging modalities for accurate assessment 1, 5
- Be aware that BBB may be the first manifestation of progressive cardiac conduction disease, cardiomyopathy, or other structural heart disease 1, 3