Value of the sodium-channel blocker challenge in Brugada syndrome.
AIMS
Intravenous drug challenge is frequently performed to unmask Brugada syndrome (BrS). However, its true sensitivity has never been assessed. We used the obligate BrS transmitters in families affected by BrS to evaluate the true accuracy of drug challenge.


METHODS
All consecutive patients from 2000 to 2014 who underwent drug challenge during familial screening for BrS were included in the study. Obligate BrS transmitters were defined as the presence of a descendant and non-descendant first-degree relative affected by BrS. Two physicians blinded to the clinical and genetic status reviewed the data.


RESULTS
Among 705 drug challenges performed in 149 families, 50 were performed in obligate transmitters from 42 different families. SCN5A mutations were identified in 20 families. Two obligate transmitters were not carrier of the familial mutation. Based on obligate transmitters, sensitivity was 100% for Ajmaline vs 77% for Flecainide (P=0.002). Based on the presence of the familial SCN5A mutation in all family relatives, sensitivity and specificity of sodium channel blocker challenge were respectively 78% (95/122) and 46% (68/148). During a median follow-up of 91 (26-136) months, 2 ventricular fibrillations occurred in obligate transmitters.


CONCLUSION
We demonstrated that Ajmaline challenge presents an excellent sensitivity that may rule out the diagnosis of BrS when negative. Conversely, a negative Flecainide challenge may not prevent from Brs inheritance and risk of SCD. This may lead to suggest systematic use of Ajmaline during drug challenge.
['Therasse|Dylan|D|', 'Sacher|Frederic|F|', 'Babuty|Dominique|D|', 'Mabo|Philippe|P|', 'Mansourati|Jacques|J|', 'Kyndt|Florence|F|', 'Redon|Richard|R|', 'Schott|Jean Jacques|JJ|', 'Barc|Julien|J|', 'Probst|Vincent|V|', 'Gourraud|Jean-Baptiste|JB|']
D061605:Administration, Intravenous D000328:Adult D000404:Ajmaline D053840:Brugada Syndrome D004562:Electrocardiography D005260:Female D005500:Follow-Up Studies D006801:Humans D008297:Male D008875:Middle Aged D062554:NAV1.5 Voltage-Gated Sodium Channel D011446:Prospective Studies D016037:Single-Blind Method D026941:Sodium Channel Blockers
Brugada syndrome Ajmaline Flecainide Sodium channel blocker challenge