Management of Incomplete Right Bundle Branch Block
Incomplete right bundle branch block (RBBB) typically requires no specific treatment and can be managed with observation only in asymptomatic patients without evidence of underlying cardiac disease.
Definition and Prevalence
- Incomplete RBBB is defined by the same QRS morphology criteria as complete RBBB but with a QRS duration between 110 and 119 ms 1
- RBBB (both complete and incomplete) is uncommon in the general population, occurring in less than 2% of athletes' ECGs and may represent a potential marker of underlying cardiovascular disease 1
- Incomplete RBBB is more common in men and athletes 2
Initial Assessment
- Evaluate for associated symptoms such as syncope, presyncope, dizziness, fatigue, or exercise intolerance 3
- Assess for underlying structural heart disease through cardiac imaging (echocardiography) 3
- Determine if incomplete RBBB is isolated or associated with other conduction abnormalities (e.g., left anterior or posterior hemiblock, first-degree AV block) 3
Management Approach for Asymptomatic Patients
- No specific treatment is required for asymptomatic patients with isolated incomplete RBBB 3, 4
- Regular follow-up with ECG monitoring is recommended to detect potential progression to complete RBBB or more complex conduction disorders 4
- Incomplete RBBB is not associated with adverse outcomes in patients without cardiovascular disease 5
Management for Special Circumstances
- If incomplete RBBB progresses to complete RBBB, patients should be monitored more closely as they may have a higher incidence of heart failure and chronic kidney disease 5
- Athletes with incomplete RBBB who have no symptoms and no evidence of structural heart disease can participate in all competitive athletics 1
- Differentiate incomplete RBBB from pathological patterns such as Brugada ECG pattern, right ventricular enlargement, arrhythmogenic right ventricular cardiomyopathy, and Wolf-Parkinson-White syndrome 2
When Further Evaluation is Needed
- Further cardiac evaluation is warranted if:
- Symptoms are present (syncope, presyncope, exercise intolerance) 3
- There are abnormal findings on physical examination 2
- There is a family history of premature cardiac disease or sudden cardiac death 1
- Incomplete RBBB is accompanied by other conduction abnormalities 3
- Incomplete RBBB is newly developed in the setting of acute coronary syndrome 6
Additional Testing When Indicated
- Echocardiography to exclude structural heart disease, particularly atrial septal defect which can be associated with RBBB 2, 7
- Exercise stress testing to assess for exercise-induced conduction abnormalities 1
- 24-hour ECG monitoring if symptoms suggest intermittent higher-degree blocks 1
- Electrophysiologic studies are rarely necessary but may be considered in highly selected cases with concerning symptoms 1
Key Points to Remember
- The RSR' pattern with QRS width below 100 ms may represent a normal crista supraventricularis pattern rather than true incomplete RBBB 2
- Incomplete RBBB can appear due to higher placement of ECG electrodes V1 and V2 or in patients with pectus excavatum 2
- In athletes, incomplete RBBB is generally considered a benign finding unless there are concerning symptoms, family history, or left ventricular hypertrophy 2