Flecainide challenge in pediatric Brugada syndrome: adding further data to this diagnostic tool

Abstract

BACKGROUND: Brugada syndrome (BrS) is a rare, aggressive and inherited cardiac disease leading to potentially lethal ventricular arrhythmias and sudden cardiac death in young subjects with structurally normal hearts. Its diagnosis requires a Brugada type 1 electrocardiographic pattern, characterized by a coved-type ST-segment elevation in at least one of the right precordial leads. In order to unmask the concealed pattern, the administration of sodium channel blockers drugs (ajmaline, flecainide or procainamide) is stablished as diagnostic test. Little is known about pediatric BrS, as most affected patients are adults. HYPOTHESES & OBJECTIVES: This cross-sectional study describes the diagnostic approach of pediatric patients with suspected BrS on whom a flecainide challenge has been performed. METHODS: A registry of the standard diagnostic management of 180 anonymized pediatric patients with suspected BrS was described, including their demographics, clinical characteristics, all diagnostic tests performed and their results. It was analyzed in comparison with their flecainide challenge result. RESULTS: 180 pediatric patients were included: 112 were asymptomatic and were studied for either familiar screening (71 patients, with five positive flecainide challenges) or ECG abnormalities (41, and 23 had a positive result, with a p-value<0.001). A total of 28 asymptomatic patients had a positive test (25%). The remaining 68 patients were symptomatic (unexplained syncope, febrile seizures or episodes of aborted SCD) and 14 had positive flecainide challenges (21%), without significant associations. The analysis of age and gender with the result of their flecainide test showed p-values of <0.001 and 0.003, respectively. Also, having family history of BrS or positive genetic tests for SCNA5A showed p-values<0.001. Some adverse effects during flecainide challenges were registered: transient photopsies (37), transient pelvic warm sensations (48) and one case of cardiac electromechanical dissociation. CONCLUSIONS: To our knowledge, this is the largest study of children undergoing flecainide challenge for suspicion of BrS. Most patients were asymptomatic and to diagnose them can be challenging. Basal and febrile ECGs had diagnostic relevance. Also, genetic-related parameters showed an association but without a clear pattern. Symptoms did not show any association with reaching the diagnose. Analyzing age and gender parameters, it might be better to repeat the test after 15 years old, not before this age, due to the hormonal role. A total of 42 patients (23% of the 180 patients studied) were finally diagnosed of BrS thanks to a flecainide challenge, but it is believed that using ajmaline would improve the diagnostic efficiency. However, some acute adverse effects were registered (including a life-threatening arrhythmia), thus it is not a risk-free diagnostic tool