From the Guidelines
RBBB on ECG is indicative of STEMI if ST-elevation is present, while ST-segment depression in lead I, aVL, and V5-6 is indicative of NSTE-ACS, and patients with RBBB and acute chest pain should await the result of the hs-cTn T/I measurement at presentation. The ECG changes in RBBB include a widened QRS complex (greater than 120 milliseconds), an RSR' pattern in lead V1, and wide S waves in leads I and V6, which occur due to delayed right ventricular depolarization 1. RBBB can be a normal variant in healthy individuals or may indicate underlying heart disease such as coronary artery disease, cardiomyopathy, or congenital heart defects.
Key Points to Consider
- Isolated RBBB typically requires no specific treatment, but patients should undergo evaluation for underlying cardiac conditions, especially if the RBBB is newly discovered 1.
- The clinical significance of RBBB depends on the presence of associated symptoms and underlying heart disease rather than the conduction abnormality itself.
- More than 50% of patients presenting with acute chest pain and RBBB to the emergency department will ultimately be found to have a diagnosis other than MI, and should await the result of the hs-cTn T/I measurement at presentation 1.
Evaluation and Management
- Evaluation for underlying cardiac conditions may include echocardiography, stress testing, or other cardiac imaging.
- The result of the hs-cTn T/I measurement at presentation should be integrated into the decision regarding immediate coronary angiography 1.
- Novel ECG algorithms using digital ECG data are in development, and it is advisable to perform ECG interpretation using remote technologies at the pre-hospital stage 1.
From the Research
ECG Changes in RBBB
- RBBB is characterized by a widened QRS complex and changes in the directional vectors of the R and S waves on a 12-lead ECG 2.
- The normal sequence of activation is altered in RBBB, resulting in a characteristic appearance on the ECG 2.
- RBBB can be associated with increased cardiovascular morbidity and mortality, particularly in patients with heart diseases like acute coronary syndromes (ACS) 3.
Diagnostic Challenges and Prognosis
- The prognostic implications of RBBB in the general population and in patients with heart diseases are still conflicting 3.
- RBBB in ACS patients is considered a STEMI equivalent, but further differentiation is necessary in this group 3.
- The presence of RBBB can affect the diagnostic accuracy of STEMI criteria, and patients with RBBB may require additional diagnostic procedures 3, 4.
- RBBB can be associated with poor outcomes compared to non-BBB and LBBB patients, particularly in high-risk patients for ST-elevation myocardial infarction (STEMI) 3.
Prevalence and Significance
- The prevalence of RBBB in patients with suspected ACS is around 3%, and it is associated with elevated mortality 3.
- Exercise-induced RBBB is a rare occurrence during routine clinical exercise testing and appears to be benign 5.
- RBBB can be associated with more severe and extensive left ventricular myocardial damage, as well as more severe coronary artery disease (CAD) 6.