Dataset Information

Effect of Flecainide on Multifocal Ectopic Purkinje-Related Premature Contractions in an R814W SCN5A Carrier.

ABSTRACT: Multifocal ectopic Purkinje-related premature contraction (MEPPC) is an autosomal dominant SCN5A channelopathy characterized by frequent multiform premature ventricular contractions originating from the His-Purkinje system. We present a patient with an MEPPC phenotype whose genetic testing identified a pathogenic SCN5A (HGNC:10593) variant amenable to precision antiarrhythmic therapy with flecainide.

SUBMITTER: Ahamed H

PROVIDER: S-EPMC10920139 | biostudies-literature | 2024 Mar

REPOSITORIES: biostudies-literature

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Publications

Effect of Flecainide on Multifocal Ectopic Purkinje-Related Premature Contractions in an R814W SCN5A Carrier.

Ahamed Hisham H Gopi Arun A

JACC. Case reports 20240123 5

Multifocal ectopic Purkinje-related premature contraction (MEPPC) is an autosomal dominant SCN5A channelopathy characterized by frequent multiform premature ventricular contractions originating from the His-Purkinje system. We present a patient with an MEPPC phenotype whose genetic testing identified a pathogenic SCN5A (HGNC:10593) variant amenable to precision antiarrhythmic therapy with flecainide. ...[more]

PMID: 38464806

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Project description:BackgroundWe identified a novel SCN5A variant, E171Q, in a neonate with very frequent ectopy and reduced ejection fraction which normalized after arrhythmia suppression by flecainide. This clinical picture is consistent with multifocal ectopic Purkinje-related premature contractions (MEPPC). Most previous reports of MEPPC have implicated SCN5A variants such as R222Q that neutralize positive charges in the S4 voltage sensor helix of the channel protein NaV1.5 and generate a gating pore current.Methods and resultsE171 is a highly conserved negatively-charged residue located in the S2 transmembrane helix of NaV1.5 domain I. E171 is a key component of the Gating Charge Transfer Center, a region thought to be critical for normal movement of the S4 voltage sensor helix. We used heterologous expression, CRISPR-edited induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs), and molecular dynamics simulations to demonstrate that E171Q generates a gating pore current, which was suppressed by a low concentration of flecainide (IC50 = 0.71±0.07 µM). R222Q shifts voltage dependence of activation and inactivation in a negative direction but we observed positive shifts with E171Q. E171Q iPSC-CMs demonstrated abnormal spontaneous activity and prolonged action potentials. Molecular dynamics simulations revealed that both R222Q and E171Q proteins generate a water-filled permeation pathway that underlies generation of the gating pore current.ConclusionPreviously identified MEPPC-associated variants that create gating pore currents are located in positively-charged residues in the S4 voltage sensor and generate negative shifts in the voltage dependence of activation and inactivation. We demonstrate that neutralizing a negatively charged S2 helix residue in the Gating Charge Transfer Center generates positive shifts but also create a gating pore pathway. These findings implicate the gating pore pathway as the primary functional and structural determinant of MEPPC and widen the spectrum of variants that are associated with gating pore-related disease in voltage-gated ion channels.

Project description:The prolongation of the QT interval represents the main feature of the long QT syndrome (LQTS), a life-threatening genetic disease. The heterozygous SCN5A V411M mutation of the human sodium channel leads to a LQTS type 3 with severe proarrhythmic effects due to an increase in the late component of the sodium current (INaL). The two sodium blockers flecainide and ranolazine are equally recommended by the current 2015 ESC guidelines to treat patients with LQTS type 3 and persistently prolonged QT intervals. However, awareness of pro-arrhythmic effects of flecainide in LQTS type 3 patients arose upon the study of the SCN5A E1784K mutation. Regarding SCN5A V411M individuals, flecainide showed good results albeit in a reduced number of patients and no evidence supporting the use of ranolazine has ever been released. Therefore, we ought to compare the effect of ranolazine and flecainide in a SCN5A V411M model using an in-silico modeling and simulation approach. We collected clinical data of four patients. Then, we fitted four Markovian models of the human sodium current (INa) to experimental and clinical data. Two of them correspond to the wild type and the heterozygous SCN5A V411M scenarios, and the other two mimic the effects of flecainide and ranolazine on INa. Next, we inserted them into three isolated cell action potential (AP) models for endocardial, midmyocardial and epicardial cells and in a one-dimensional tissue model. The SCN5A V411M mutation produced a 15.9% APD90 prolongation in the isolated endocardial cell model, which corresponded to a 14.3% of the QT interval prolongation in a one-dimensional strand model, in keeping with clinical observations. Although with different underlying mechanisms, flecainide and ranolazine partially countered this prolongation at the isolated endocardial model by reducing the APD90 by 8.7 and 4.3%, and the QT interval by 7.2 and 3.2%, respectively. While flecainide specifically targeted the mutation-induced increase in peak INaL, ranolazine reduced it during the entire AP. Our simulations also suggest that ranolazine could prevent early afterdepolarizations triggered by the SCN5A V411M mutation during bradycardia, as flecainide. We conclude that ranolazine could be used to treat SCN5A V411M patients, specifically when flecainide is contraindicated.

Dataset Information

Effect of Flecainide on Multifocal Ectopic Purkinje-Related Premature Contractions in an R814W SCN5A Carrier.

Publications

Effect of Flecainide on Multifocal Ectopic Purkinje-Related Premature Contractions in an R814W SCN5A Carrier.

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