Sodium-channel blocker challenge in the familial screening of Brugada syndrome: safety and predictors of positivity

Dylan Therasse (1) , Frédéric Sacher (2) , Bertrand Petit (3) , Dominique Babuty (4) , Philippe Mabo (5) , Raphael Martins (6) , Laurence Jesel (7) , Philippe Maury (8) , Jean Luc Pasquie (9) , Jacques Mansourati , Jean Marc Dupuis , Florence Kyndt (1) , Aurélie Thollet (1) , Beatrice Guyomarch (1) , Julien Barc (1) , Jean Jacques Schott (1) , Hervé Le Marec (1) , Richard Redon (1) , Vincent Probst (1) , Jean-Baptiste Gourraud (1)

1 ITX - ITX - unité de recherche de l'institut du thorax
2 IHU-LIRYC
3 CHR La réunion
4 CHU Trousseau [Tours]
5 Service de cardiologie et maladies vasculaires [Rennes] = Cardiac, Thoracic, and Vascular Surgery [Rennes]
6 LTSI - Laboratoire Traitement du Signal et de l'Image
7 CHU Strasbourg - Centre Hospitalier Universitaire [Strasbourg]
8 CHU Toulouse - Centre Hospitalier Universitaire de Toulouse
9 CHU Montpellier

Background - Sodium-channel blocker challenge (SCBC) is frequently performed to unmask Brugada syndrome. Objective - We aim to identify predictors of positivity and complications of SCBC in the setting of familial screening of Brugada syndrome. Methods - All consecutive patients from 2000 to 2014 who benefit from a sodium-channel blocker and belong to a family with at least 2 subjects affected by the syndrome were enrolled and followed prospectively. Data were reviewed by 2 physicians blinded to the clinical and genetic status. Results - Of the 672 SCBCs performed in 137 families, 337 (50%) were positive. Multivariate analysis identified ajmaline (odds ratio [OR] 2.98; 95% CI 1.65-4.91) and a significant S wave in lead DII (OR 3.11; 95% CI 2.12-4.58), DIII (OR 2.75; 95% CI 1.78-4.25), or V (OR 3.71; 95% CI 2.54-5.44) as predictors of a positive SCBC (P < .0001). Eleven patients (1.6%) presented complications (10 ventricular arrhythmias and 1 atrial flutter), but no deaths occurred. Familial history of complications (OR 41; lower quartile, upper quartile 10, 203; P < .0001), young age (P = .04), and decreased electrocardiographic conduction parameters at baseline (P = .04) were predictors of complications. QRS enlargement during SCBC was not associated with complications. During a median follow-up of 106 months (lower quartile, upper quartile 54, 143 months), 11 life-threatening arrhythmias occurred. Conclusion - SCBC in the screening of familial Brugada syndrome is safe. The risk of complication is considerably increased in the case of familial history of complicated SCBC, in young patients, and in the presence of decreased electrocardiographic conduction parameters. However, QRS enlargement during the test is not directly related to complications and should not be used to prematurely stop the test unless leading to false-negative results.

Mots clés: Flecainide; Sodium-channel blocker challenge; Brugada syndrome; Complication; Ajmaline

Domaines: Ingénierie biomédicale; Cardiologie et système cardiovasculaire

Dylan Therasse, Frédéric Sacher, Bertrand Petit, Dominique Babuty, Philippe Mabo, et al.. Sodium-channel blocker challenge in the familial screening of Brugada syndrome: safety and predictors of positivity. Heart Rhythm, 2017, 14 (10), pp.1442-1448. ⟨10.1016/j.hrthm.2017.06.031⟩. ⟨hal-01650124⟩