From the Guidelines
New onset right bundle branch block (RBBB) in patients with ischemic heart disease (IHD) is a significant finding that warrants prompt cardiac assessment and may indicate worsening coronary artery disease, necessitating more aggressive management of the underlying IHD. When RBBB appears newly in a patient with known IHD, it requires evaluation for acute coronary syndrome or myocardial infarction, including a 12-lead ECG, cardiac biomarkers (troponin), and echocardiography 1. The development of RBBB in IHD patients may indicate involvement of the right coronary artery, which supplies the right bundle branch. Management depends on the clinical context - if associated with acute myocardial infarction, immediate reperfusion therapy is indicated following standard ACS protocols, as outlined in the 2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS guideline for the diagnosis and management of patients with stable ischemic heart disease 1. If found incidentally without symptoms, closer monitoring and optimization of anti-ischemic therapy is appropriate, including antiplatelet agents (aspirin 75-100mg daily), statins, beta-blockers, and ACE inhibitors as indicated by the patient's overall cardiac status. RBBB itself doesn't typically require specific treatment, but its appearance may necessitate more aggressive management of the underlying IHD. The significance of new RBBB lies in its association with increased mortality in IHD patients, as it reflects more extensive myocardial damage and potential for conduction system deterioration that could progress to complete heart block in some cases, with studies showing a 64% increased odds ratio of in-hospital death in patients with RBBB compared to those without BBB 1. Key considerations in managing patients with new onset RBBB and IHD include:
- Prompt cardiac assessment to evaluate for acute coronary syndrome or myocardial infarction
- Optimization of anti-ischemic therapy, including antiplatelet agents, statins, beta-blockers, and ACE inhibitors
- Consideration of reperfusion therapy if associated with acute myocardial infarction
- Closer monitoring for signs of conduction system deterioration or complete heart block.
From the Research
Significance of New Onset Right Bundle Branch Block (RBBB) in Patients with Ischemic Heart Disease (IHD)
- New onset RBBB in patients with acute myocardial infarction (AMI) is associated with a higher risk of long-term mortality, ventricular arrhythmia, and cardiogenic shock, but a lower risk of heart failure 2.
- The presence of RBBB may lead to the misdiagnosis of transmural ischemia and mask the early diagnosis of ST-elevation myocardial infarction 2.
- Patients with new-onset RBBB have a higher incidence of cardiogenic shock and in-hospital mortality compared to those with left bundle branch block (LBBB) 3.
- New-onset RBBB is likely to be caused by critical lesions of the left anterior descending artery (LAD) and is associated with a worse prognosis 4.
- Atypical RBBB is an independent predictor of in-hospital major adverse cardiovascular events (MACE) and 1-year mortality in patients with AMI combined with new onset RBBB 5.
Clinical Characteristics and Outcomes
- Patients with new-onset atypical RBBB have more serious clinical symptoms and clinical prognosis compared to those with typical RBBB 5.
- The evolution of typical RBBB to atypical RBBB may be avoided by immediate opening of the infarct-related vessel, leading to a better prognosis 5.
- Appropriate perioperative management of medications and clear communication between healthcare providers can reduce the incidence of perioperative cardiac events in patients with IHD 6.
Revascularization Therapies
- Revascularization therapies should be considered when persistent ischemic symptoms occur in patients with RBBB, especially new-onset RBBB 2.
- Primary percutaneous coronary intervention (PCI) may lead to resolution of the conduction delay on the discharge ECG and improve outcomes in patients with AMI and RBBB 3.