From the Guidelines
Incomplete right bundle branch block (RBBB) is a cardiac conduction abnormality that typically doesn't require specific treatment if the patient is asymptomatic, and regular cardiac follow-up is recommended. The diagnosis of incomplete RBBB is based on electrocardiogram (ECG) findings, which include an RSR' pattern in lead V1 with a QRS duration between 110 and 119 ms 1. This condition may be a normal variant, especially in young, healthy individuals, or it could represent early conduction system disease. Some key points to consider in the diagnosis and management of incomplete RBBB include:
- ECG findings: RSR' pattern in lead V1 with a QRS duration between 110 and 119 ms 1
- Asymptomatic patients: no medication or intervention is necessary, but regular cardiac follow-up is recommended 1
- Symptomatic patients: prompt medical evaluation is warranted to rule out progression of conduction disease or other cardiac issues 1
- Risk factors: patients with incomplete RBBB may have an increased risk of left ventricular systolic dysfunction, especially if they have other cardiac risk factors or symptoms 1 The most important consideration in the management of incomplete RBBB is to monitor for the development of symptoms, such as palpitations, dizziness, or syncope, which could indicate progression of conduction disease or other cardiac issues, and to provide regular cardiac follow-up to assess for any changes in the patient's condition. In terms of specific management strategies, the following may be considered:
- Regular cardiac follow-up with a primary care physician or cardiologist to monitor for any changes in the patient's condition 1
- Echocardiography to evaluate for left ventricular systolic dysfunction or other structural heart disease 1
- Ambulatory electrocardiographic monitoring to document clinically significant arrhythmias in asymptomatic patients 1
- Cardiac MRI to evaluate for subclinical cardiomyopathy or other conditions in selected patients 1
From the Research
Diagnosis of Incomplete Right Bundle Branch Block (RBBB)
- Incomplete right bundle branch block (IRBBB) is an electrocardiogram (ECG) finding that can express both benign and pathological patterns 2
- IRBBB is defined by the RSR’ pattern and a QRS width below 100 ms, which is associated with the crista supraventricularis (CSV) pattern 2
- The CSV pattern can result from posterior apex deviation, subpulmonic area delay, or late CSV activation 2
- IRBBB can appear due to higher placement of electrodes V1 and V2, pectus excavatum, or in athletes, and is considered a benign pattern unless accompanied by family history, symptoms, or left ventricular hypertrophy 2
Differentiation from Pathological Patterns
- It is necessary to differentiate IRBBB from pathological patterns such as type-2 Brugada ECG pattern, right ventricular enlargement, arrhythmogenic right ventricular cardiomyopathy, ventricular preexcitation—Wolf-Parkinson-White syndrome, and hyperkalemia 2
- Clinicians should be alert to the splitting of the second heart sound, as RBBB is a common finding in ostium secundum atrial septal defect 2
Treatment and Prognosis
- Patients with RBBB and concomitant delayed left ventricular activation may respond to cardiac resynchronization therapy (CRT) 3
- The presence of RBBB in patients with acute myocardial infarction is associated with a higher in-hospital arrhythmic risk and mortality, and a worse prognosis after discharge 4
- Complete right bundle branch block (CRBBB) is a predictor of atrial fibrillation (AF) recurrence after pulmonary vein isolation and is associated with AF development 5
- RBBB is an independent predictor of mortality in patients presenting with acute cardiac events 6