1
|
Stutzman MJ, Gao X, Kim M, Ye D, Zhou W, Tester DJ, Giudicessi JR, Shannon K, Ackerman MJ. Functional characterization and identification of a therapeutic for a novel SCN5A-F1760C variant causing type 3 long QT syndrome refractory to all guideline-directed therapies. Heart Rhythm 2023; 20:709-717. [PMID: 36731785 DOI: 10.1016/j.hrthm.2023.01.032] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 01/23/2023] [Accepted: 01/24/2023] [Indexed: 02/01/2023]
Abstract
BACKGROUND Pathogenic variants in the SCN5A-encoded Nav1.5 sodium channel cause type 3 long QT syndrome (LQT3). We present the case of an infant with severe LQT3 who was refractory to multiple pharmacologic therapies as well as bilateral stellate ganglionectomy. The patient's novel variant, p.F1760C-SCN5A, involves a critical residue of the Nav1.5's local anesthetic binding domain. OBJECTIVE The purpose of this study was to characterize functionally the p.F1760C-SCN5A variant using TSA-201 and patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). METHODS Whole-cell patch clamp was used to assess p.F1760C-SCN5A associated sodium currents with/without lidocaine (Lido), flecainide, and phenytoin (PHT) in TSA-201 cells. p.F1760C-SCN5A and CRISPR-Cas9 variant-corrected isogenic control (IC) iPSC-CMs were generated. FluoVolt voltage dye was used to measure the action potential duration (APD) with/without mexiletine or PHT. RESULTS V1/2 of inactivation was right-shifted significantly in F1760C cells (-72.2 ± 0.7 mV) compared to wild-type (WT) cells (-86.3 ± 0.9 mV; P <.0001) resulting in a marked increase in window current. F1760C increased sodium late current 2-fold from 0.18% ± 0.04% of peak in WT to 0.49% ± 0.07% of peak in F1760C (P = .0005). Baseline APD to 90% repolarization (APD90) was increased markedly in F1760C iPSC-CMs (601 ± 4 ms) compared to IC iPSC-CMs (423 ± 15 ms; P <.0001). However, 4-hour treatment with 10 μM mexiletine failed to shorten APD90, and treatment with 5μM PHT significantly decreased APD90 of F1760C iPSC-CMs (453 ± 6 ms; P <.0001). CONCLUSION PHT rescued electrophysiological phenotype and APD of a novel p.F1760C-SCN5A variant. The antiepileptic drug PHT may be an effective alternative therapeutic for the treatment of LQT3, especially for variants that disrupt the Lido/mexiletine binding site.
Collapse
Affiliation(s)
- Marissa J Stutzman
- Department of Cardiovascular Medicine, Division of Heart Rhythm Services, Windland Smith Rice Genetic Heart Rhythm Clinic, Mayo Clinic, Rochester, Minnesota; Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, Minnesota; Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota
| | - Xiaozhi Gao
- Department of Cardiovascular Medicine, Division of Heart Rhythm Services, Windland Smith Rice Genetic Heart Rhythm Clinic, Mayo Clinic, Rochester, Minnesota; Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, Minnesota; Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota
| | - Maengjo Kim
- Department of Cardiovascular Medicine, Division of Heart Rhythm Services, Windland Smith Rice Genetic Heart Rhythm Clinic, Mayo Clinic, Rochester, Minnesota; Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, Minnesota; Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota
| | - Dan Ye
- Department of Cardiovascular Medicine, Division of Heart Rhythm Services, Windland Smith Rice Genetic Heart Rhythm Clinic, Mayo Clinic, Rochester, Minnesota; Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, Minnesota; Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota
| | - Wei Zhou
- Department of Cardiovascular Medicine, Division of Heart Rhythm Services, Windland Smith Rice Genetic Heart Rhythm Clinic, Mayo Clinic, Rochester, Minnesota; Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, Minnesota; Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota
| | - David J Tester
- Department of Cardiovascular Medicine, Division of Heart Rhythm Services, Windland Smith Rice Genetic Heart Rhythm Clinic, Mayo Clinic, Rochester, Minnesota; Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, Minnesota; Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota
| | - John R Giudicessi
- Department of Cardiovascular Medicine, Division of Heart Rhythm Services, Windland Smith Rice Genetic Heart Rhythm Clinic, Mayo Clinic, Rochester, Minnesota; Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, Minnesota; Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota
| | - Kevin Shannon
- Department of Pediatrics, David Geffen UCLA School of Medicine, Los Angeles, California
| | - Michael J Ackerman
- Department of Cardiovascular Medicine, Division of Heart Rhythm Services, Windland Smith Rice Genetic Heart Rhythm Clinic, Mayo Clinic, Rochester, Minnesota; Department of Pediatric and Adolescent Medicine, Division of Pediatric Cardiology, Mayo Clinic, Rochester, Minnesota; Department of Molecular Pharmacology & Experimental Therapeutics, Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, Minnesota.
| |
Collapse
|
2
|
Newlon C, Etheridge SP. Intravenous lidocaine in malignant long QT type 3: A bridge over troubled waters. Heart Rhythm 2021; 19:88-89. [PMID: 34610437 DOI: 10.1016/j.hrthm.2021.09.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 09/29/2021] [Indexed: 11/26/2022]
Affiliation(s)
- Claire Newlon
- Department of Pediatrics, Primary Children's Hospital, University of Utah, Salt Lake City, Utah
| | - Susan P Etheridge
- Department of Pediatrics, Primary Children's Hospital, University of Utah, Salt Lake City, Utah.
| |
Collapse
|