Long-term flecainide therapy in type 3 long QT syndrome

Area of Science:

• Cardiology
• Genetics
• Pharmacology

Background:

• Type 3 long QT syndrome (LQT3) is a genetic disorder caused by gain-of-function mutations in the SCN5A gene.
• Long-term data on sodium channel blockers for LQT3 management are limited.
• The D1790G mutation in SCN5A is a known cause of LQT3.

Purpose of the Study:

• To assess the long-term safety and efficacy of flecainide in LQT3 patients with the D1790G SCN5A mutation.
• To evaluate flecainide's impact on QTc interval duration and cardiac events.

Main Methods:

• A cohort of 30 patients with the D1790G SCN5A mutation were treated with flecainide.
• Patients were monitored for QTc interval changes and cardiac events over an extended period (mean 145 months).
• Analysis included baseline and on-treatment QTc measurements and event rates.

Main Results:

• Flecainide significantly shortened the mean QTc interval from 522 ms to 469 ms (P < 0.01).
• Only 13% of patients had QTc > 500 ms on flecainide, compared to 53% at baseline.
• No cardiac events occurred in compliant patients during flecainide therapy; however, 30% experienced events after discontinuation.

Conclusions:

• Long-term flecainide therapy demonstrates relative safety and efficacy in LQT3 patients with the D1790G SCN5A mutation.
• Flecainide effectively manages QTc prolongation and reduces cardiac event risk in this specific patient population.
• Discontinuation of flecainide may be associated with an increased risk of cardiac events.