Long-term flecainide therapy in type 3 long QT syndrome.
Type 3 long QT syndrome (LQT3) is caused by gain-of-function mutations in the cardiac sodium channel gene (SCN5A). Previous reports on the long-term use of sodium channel blockers in LQT3 are sparse. The objective of the current study was to evaluate the long-term safety and efficacy of flecainide therapy in patients with LQT3 who carry the D1790G SCN5A mutation.



The study population comprised 30 D1790G carriers who were treated with flecainide and followed for 1-215 months (mean 145 ± 54 months, median 140 months). The mean baseline (off-drug) QTc was 522 ± 45 ms, and shortened to 469 ± 36 ms with flecainide therapy, a mean decrease of 53 ms [10.1%] (P < 0.01). A QTc longer than 500 ms was evident in 53% of carriers at baseline, and only in 13% on flecainide. All carriers while being compliant with flecainide therapy had no cardiac events during an average follow up of 83 ± 73 months. Twenty carriers stopped flecainide after an average follow up of 40 ± 42 months without symptoms. Six of them (30%) had cardiac events 1-11 months after stopping flecainide. Flecainide induced the appearance of Brugada pattern in six carriers (20%, 5 males), was stopped in three and was not associated with arrhythmia. Sinus-node dysfunction was evident in six carriers (20%) and was fully corrected by flecainide in three.



These data suggest that long-term flecainide therapy is relatively safe and effective among LQT3 patients who carry the D1790G SCN5A mutation.
Department of Cardiology, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
Ehud
E
Chorin
Department of Cardiology, Shaare Zedek Medical Center, Jerusalem, Israel.
Rivki
R
Taub
Department of Cardiology, Shaare Zedek Medical Center, Jerusalem, Israel.
Aron
A
Medina
Department of Cardiology, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
Nir
N
Flint
Department of Cardiology, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
Sami
S
Viskin
Department of Cardiology, Tel Aviv Sourasky Medical Center and Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
Jesaia
J
Benhorin
D000293:Adolescent; D000328:Adult; D000889:Anti-Arrhythmia Agents / Q000008:administration & dosage* / Q000009:adverse effects; D053840:Brugada Syndrome / Q000139:chemically induced; D000075224:Cardiac Conduction System Disease / Q000175:diagnosis / Q000188:drug therapy* / Q000235:genetics / Q000503:physiopathology; D002648:Child; D000066491:Clinical Decision-Making; D004562:Electrocardiography; D005260:Female; D005424:Flecainide / Q000008:administration & dosage* / Q000009:adverse effects; D020022:Genetic Predisposition to Disease; D006801:Humans; D008133:Long QT Syndrome / Q000175:diagnosis / Q000188:drug therapy* / Q000235:genetics / Q000503:physiopathology; D008297:Male; D009154:Mutation; D062554:NAV1.5 Voltage-Gated Sodium Channel / Q000235:genetics; D018579:Patient Selection; D010641:Phenotype; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D061567:Voltage-Gated Sodium Channel Blockers / Q000008:administration & dosage* / Q000009:adverse effects; D055815:Young Adult
D000889:Anti-Arrhythmia Agents; D062554:NAV1.5 Voltage-Gated Sodium Channel; C568320:SCN5A protein, human; D061567:Voltage-Gated Sodium Channel Blockers; D005424:Flecainide
Flecainide ; Long QT syndrome; Long QT syndrome type 3; Sodium channel blocker; Sodium channels