223 Fast or slow infusion rate for ajmaline challenge in suspicion of Brugada Syndrome?

Na channel blockade challenge is the cornerstone of the diagnosis of Brugada Syndrome (BS). Since the second conference of consensus, the infusion rate of ajmaline during Na channel blockade challenge consist in 1mg/kg during 5 minutes. In clinical practice, infusion rate of ajmaline differs between centers; in fact, there's no data that compare two infusion rates during ajmaline challenge. Fast infusion rate is used in centers having experience of ajmaline in the diagnostic management of conductive diseases. Slow infusion rate is advocated by others owing to a risk of pro arrhythmia.Aim of the studyThe aim of the study is to compare the results and the safety of a fast and of a slow infusion rate during ajmaline challenge in suspicion of BS.Methods32 patients (M=26, F=6; 41±12 years) who had an ajmaline challenge according to a type 2 (69%) or 3 ECG (31%), mainly for a familial screening (37,5%), were prospectively included. They underwent 2 ajmaline challenges on separate days. Ajmaline (1mg/kg) was infused either during a rate of 1mg/s or during 10 minutes. Primary end point was the result of the challenge. Secondary end points were the occurrence of ventricular arrhythmia and the magnitude of ECG modifications.ResultsNo differences were observed between the two protocols as regards positive and negative results. No Ventricular Tachycardia occurred. No differences were observed on the occurrence of isolated ventricular ectopic beats (p=.5). Heart rate increased more during slow test (15.5% vs 11%, p=.04). Variations of corrected QT, PR interval, QRS duration and J wave elevation were similar in both challenges.ConclusionFast and slow infusion rate of ajmaline afforded the same results. Ventricular ectopic beats occurred with the same incidence in both tests. In clinical practice, we could reduce the time procedure of the ajmaline challenge, as concerns type 2 or 3 Brugada Syndrome ECG, particularly for a familial screening