Difference of Class III Drug Effects after ICD Shock in Brugada Syndrome

Abstract

Purpose: To compare drug effects on the spatial and transmural dispersion of repolarization (SDR and TDR) just after ICD shock between amiodarone (AMD) and nifekalant (NIF) in patients with Brugada syndrome (BS). Methods: We enrolled 22 consecutive patients with BS with ICD, and divided them into 2 groups: AMD group (N=12) and NIF group (N=10). We recorded 87-lead body surface ECGs before (CONTROL) and after only drug administration, and just after ICD shocks with and without drug. Corrected QT interval (QTc), QT peak interval (cQTp), and TDR (cTDR; QTc-cQTp) were measured. As an index of SDR, the dispersion of QTc (QTc-D) in 87 leads was measured. Results: Compared with CONTROL, QTc-D in both groups was significantly deteriorated by ICD shocks (AMD group; 85±12, 105±19 ms1⁄2, and NIF group; 79±10, 96±7 ms1⁄2, respectively, p<0.05). QTc-D with drug did not differ between with and without ICD shocks (AMD group; 91±19, 94±15 ms1⁄2, and NIF group; 80±13, 79±14 ms1⁄2, respectively). AMD did not increase cTDR. cTDR after drug with and without ICD shock in NIF group were larger than those in AMD group (NIF group; 148±24, 144±28 ms1⁄2, and AMD group; 123±29, 123±25 ms1⁄2, respectively, p<0.05). Conclusion: Both drugs suppressed the deterioration of SDR by ICD shocks. AMD may be more useful to suppress instability of repolarization just after ICD shocks.