Prognosis of asymptomatic patients who underwent a sodium channel blocker challenge
J Gourraud, P Petit, V Cotard, A Thollet, N Behar, J Mansourati, B Pierre, F Sacher, G Clerici, V ProbstAbstract
Background
Brugada syndrome (BrS) is an inherited arrhythmia syndrome with an increased risk of of syncope and SCD. To rule out the diagnosis, sodium channel blocker (SCB) is used in routine practice, but its value is matter to debate due to an uncertain risk-benefit balance. The aim of this study is to specify the prognosis of asymptomatic patients who underwent a SCB challenge.
Methods
Consecutive patients from families affected with BrS and who underwent a SCB challenge were recruited in a multicentric prospective registry in France (15 centers) between 1994 and 2025.
Results
A total of 2456 patients (1324 males (54%), mean age 41 [28-54] years) were enrolled including 2132 (87%) after ajmaline challenge and 324 (13%) after flecainide challenge. Two hundred and fifty patients (16%) were carriers of a pathogenic/likely pathogenic variant in SCN5A gene.
SCB challenge was positive in 1170 patients (SCBC+ group) and negative in 1286 (SCBC- group). Patients of SCBC+ group were older (45 [33 - 56] years vs 38 [24 – 53], p<0,001) and presented ECG with longer PR (120 vs 110 ms, p<0,001), longer QRS (120 vs 110 ms, p<0,001) and longer QTc interval (400 vs 390 ms) at baseline.
Mean follow-up were 7,4 [3,3-12,4] years (6,5 [2,9-11,9] in SCBC+ group vs 8,9 [4,5-13,1] in SCBC- group, p<0,001). During the follow-up, 85 patients (3,5%) died without significative difference between the two groups (47 (4%) for SCBC+ group vs 38 (3%) for SCBC- group, p=0,2). Age at death were similar (68 [60-79] for SCBC+ group vs 63 [52-84] SCBC- group).
In patients with a minimal follow-up of 1 year (1241 patients, 858 SCBC+, 383 SCBC-) 16 (1,3%) lethal arrhythmic events were identified. A SCD was reported for 9 (1,05%) patients and appropriate ICD therapy for 7 (0,8%) patients. The annual rate of event was 0,22%/year for SCBC+ group. No arrhythmic events was identified after a negative SCBC.
Conclusion
Asymptomatic Brs patients have a good prognosis with an annual event rate of 0,22%/year. No lethal arrhythmic event was reported after a negative SCBC suggesting a potential role in arrhythmic risk stratification.