From the Guidelines
An Incomplete Right Bundle Branch Block (IRBBB) on an electrocardiogram (ECG) is generally considered a normal variant in healthy adolescents, including 14-year-old males. This finding is quite common in children and young adults and typically does not indicate any underlying heart disease or require further evaluation in the absence of symptoms or other concerning ECG abnormalities [ 1 ]. IRBBB is characterized by an RSR' pattern in lead V1 with a QRS duration less than 120 milliseconds. The physiological explanation for this finding relates to normal developmental changes in the conduction system of the heart during childhood and adolescence. As the right ventricle develops and the heart grows, there can be slight delays in right ventricular activation that do not reach the threshold of a complete bundle branch block.
Some key points to consider in the interpretation of ECG findings in adolescents include:
- Normal ECG findings in athletes, as outlined in international recommendations, include increased QRS voltage, incomplete RBBB, early repolarization, and juvenile T-wave patterns [ 1 ].
- The presence of an IRBBB in an asymptomatic adolescent without a significant family history of cardiac disease does not necessitate further evaluation [ 1 ].
- Athletic adolescents may have an even higher prevalence of IRBBB due to physiological adaptations to regular exercise [ 1 ].
- Other ECG patterns, such as the "juvenile" ECG pattern characterized by T-wave inversion in the anterior precordial leads, may also be considered normal in adolescents up to the age of 16 years [ 1 ].
In the context of real-life clinical medicine, the presence of an isolated IRBBB in a healthy 14-year-old male does not require treatment or activity restrictions, provided there are no cardiac symptoms, family history of sudden cardiac death, or other concerning findings on physical examination [ 1 ].
From the Research
Incomplete Right Bundle Branch Block (IRBBB) in a Healthy 14-Year-Old Male
- IRBBB is a common electrocardiogram (ECG) finding at all ages, more frequent in men and athletes 2.
- It is usually considered a benign pattern unless there is a family history, symptoms, or left ventricular hypertrophy 2.
- IRBBB can appear due to higher placement of electrodes V1 and V2, pectus excavatum, or in athletes, and is considered benign in these cases 2.
- However, 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.
Prevalence and Incidence of IRBBB
- The prevalence of IRBBB in the general population is around 4.6% 3.
- IRBBB is not associated with adverse outcomes, and patients with IRBBB do not have an increased risk of cardiovascular morbidity and mortality 3.
- However, patients with IRBBB who progress to complete RBBB may have a higher incidence of heart failure and chronic kidney disease 3.
Diagnosis and Interpretation of IRBBB
- The diagnosis of IRBBB requires careful interpretation of the ECG, and the interobserver agreement among physicians specialized in ECG interpretation is very good 4.
- The concordance in the diagnosis of IRBBB among primary care researchers and a cardiologist is high, with a Fleiss' kappa index of 0.71 4.
- However, the variability in the diagnosis of IRBBB is greater than that of complete RBBB 4.
Clinical Significance of IRBBB in a Healthy 14-Year-Old Male
- In the absence of any symptoms or family history of cardiovascular disease, IRBBB in a healthy 14-year-old male is likely to be a benign finding 2, 3.
- However, it is essential to exclude any underlying heart disease, and a thorough clinical examination and further evaluation may be necessary to confirm the diagnosis 2.