High prevalence of concealed Brugada syndrome in patients with atrioventricular nodal reentrant tachycardia.

Background: Atrioventricular nodal reentrant tachycardia (AVNRT) may coexist with Brugada syndrome (BrS).

Objectives: The present study was designed to determine the prevalence of drug-induced type 1 Brugada ECG pattern (concealed BrS) in patients presenting with clinical spontaneous AVNRT and to investigate their electrocardiographic, electrophysiological, and genetic characteristics.

Methods: Ninety-six consecutive patients without any sign of BrS on baseline electrocardiogram undergoing electrophysiological study and ablation for symptomatic, drug-resistant AVNRT and 66 control subjects underwent an ajmaline challenge to unmask BrS. Genetic screening was performed in 17 patients displaying both AVNRT and BrS.

Results: A concealed BrS electrocardiogram was uncovered in 26 of 96 patients with AVNRT (27.1%) and in 3 of 66 control subjects (4.5%) (P ≤ .001). Patients with concealed BrS were predominantly female patients (n=23 [88.5%] vs n=44 [62.9%], P = .015), had higher prevalence of chest pain (n=10 [38.5%] vs n=13 [18.6%], p=0.042), migraine headaches (n=10 [38.5%] vs n=10 [14.2%], p=0.008), and drug-induced initiation and/or worsening of duration and/or frequency of AVNRT (n=4 [15.4%] vs n=1 [1.4%], p=0.006) as compared to patients with AVNRT without BrS. Genetic screening identified 19 mutations or rare variants in 13 genes in 13 of 17 patients with both AVNRT and BrS (yield = 76.5%). Ten of these 13 genotype-positive patients (76.9%) harbored genetic variants known or suspected to cause a loss of function of cardiac sodium channel current (SCN5A, SCN10A, SCN1B, GPD1L, PKP2, and HEY2).

Conclusion: Our results suggest that spontaneous AVNRT and concealed BrS co-occur, particularly in female patients, and that genetic variants that reduce sodium channel current may provide a mechanistic link between AVNRT and BrS and predispose to expression of both phenotypes.