192 Prevalence and significance of right bundle branch block in young individuals; the experience of a nationwide cardiac screening programme

BackgroundThere is limited information on the clinical significance of complete right bundle branch block (CRBBB) in young asymptomatic individuals. We sought to determine the prevalence and prognostic significance of CRBBB by reporting on clinical outcomes of a nationwide cardiac screening programme for young individuals in the United Kingdom.MethodsBetween 2007 and 2018, 104,369 consecutive individuals, aged 14 to 35 years, underwent voluntary cardiac screening (mean age 20.2 ± 6.2 years, 62% male, 89% white, 91% non-athletes). Initial evaluation consisted of a health questionnaire (HQ), electrocardiogram (ECG) and clinical consultation. Selective on-site transthoracic echocardiography (TTE) was available at the discretion of the consulting physician. Secondary cardiac evaluation was recommended for individuals with abnormal findings. CRBBB was classified as ‘isolated’ or ‘non-isolated’ based on the absence or presence, respectively, of concomitant cardiovascular symptoms, relevant family history and other ECG abnormalities (Table 1). Follow-up data were obtained via telephone consultations.ResultsOne hundred and fifty-four (0.1%) individuals were identified with CRBBB (Figure 1). The mean QRS duration was 131 ± 12 ms. CRBBB was more prevalent in males compared to females (0.22% vs. 0.06%, p < 0.05) and in athletes compared to non-athletes (0.26% vs. 0.14%, p < 0.05). There was no significant difference in terms of age or ethnicity. The majority (n=110; 74%) of individuals presented with isolated CRBBB. Of the 39 (26%) individuals with non-isolated CRBBB, 3 (2%) had CRBBB with associated symptoms and 36 (24%) had CRBBB and additional ECG finding (Table 2).On-site TTE and or follow-up was available for 149 (97%) individuals. On-site TTE identified 4 individuals with atrial septal defects (ASD). During a mean follow-up period of 7.3 ± 2.7 years, a further 3 individuals were identified with CRBBB-related conditions, including 1 with Brugada syndrome, 1 with progressive cardiac conduction disease (PCCD) and 1 with atrial fibrillation (AF).A total of 7 (4%) individuals were identified with CRBBB-related conditions; including 4 (3%) with ASD, 1 (0.7%) with Brugada syndrome, 1 (0.7%) with PCCD and 1 (0.7%) with AF. An additional 2 (1%) individuals were identified with non-CRBBB-related cardiac conditions which could be considered incidental findings; including 1 (0.7%) with mitral valve prolapse, and 1 (0.7%) aortic coarctation.The prevalence of CRBBB-related c