From the Guidelines
Sinus rhythm with Right Bundle Branch Block (RBBB) on an EKG is generally a benign finding that does not require specific treatment if the patient is asymptomatic, but it warrants evaluation for underlying causes and regular follow-up to monitor for any changes in cardiac function. According to the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1, RBBB is defined by a QRS duration ≥120 ms, an rsr', rsR, rSR, or rarely a qR pattern in leads V1 or V2, and an S wave of greater duration than the R wave or >40 ms in leads I and V6. Key characteristics of RBBB include:
- QRS duration ≥120 ms
- Specific patterns in lead V1 (rsr', rsR, rSR, or qR)
- S wave characteristics in leads I and V6 While RBBB can occur in healthy individuals, it may also be associated with underlying conditions such as hypertension, coronary artery disease, pulmonary embolism, or congenital heart disease. The guideline 1 emphasizes the importance of evaluating for underlying causes, especially if the RBBB is new, and considering a cardiac workup including echocardiography to assess for structural heart disease. Regular follow-up with a healthcare provider is recommended to monitor for any changes in cardiac function or development of symptoms that might indicate progression to more serious conduction abnormalities.
From the Research
Sinus Rhythm with RBBB on EKG
- A sinus rhythm with Right Bundle Branch Block (RBBB) on an electrocardiogram (EKG) can be an indicator of various cardiac conditions, including coronary artery disease and myocardial infarction 2.
- The presence of RBBB in patients with ST-elevation myocardial infarction (STEMI) is associated with increased morbidity and mortality, and may indicate more extensive myocardial involvement 2.
- Exercise-induced RBBB is a rare occurrence during routine clinical exercise testing, and its prognostic significance is still a topic of debate, with some studies suggesting it may be benign 3.
- Chronic complete RBBB is often associated with comorbidities such as hypertension, diabetes, coronary artery disease, and valvular heart disease, and is commonly found in patients with significant obstructive coronary artery disease 4.
- The presence of RBBB in patients with acute congestive heart failure is a powerful predictor of mortality, with a two-fold increase in mortality compared to patients without RBBB 5.
Clinical Implications
- Patients with sinus rhythm and RBBB on EKG should be evaluated for underlying cardiac conditions, including coronary artery disease and myocardial infarction 2, 4.
- The presence of RBBB in patients with STEMI or acute congestive heart failure should prompt aggressive management and close monitoring, as these patients are at higher risk of adverse outcomes 2, 5.
- Further research is needed to fully understand the prognostic significance of exercise-induced RBBB and its implications for clinical practice 3.