Long Term Flecainide Therapy in Type-3 Long QT Syndrome

The long-term effects of flecainide therapy in patients with type 3 long QT syndrome (LQT3) have not been studied. The current study reports the long-term safety and efficacy of flecainide therapy in thirty LQT3 patients who are carriers of the D1790G SCN5A mutation. Carriers (mean age 30 years, 17 females) were treated with flecainide (mean dose 142 mg/day) and followed for 3-214 months (mean 145 months, 360 patient years). 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. These effects were well sustained during follow-up in all patients. All carriers while being fully compliant with flecainide therapy had no cardiac events during an average follow up of 83 months. 20 carriers stopped flecainide after an average follow up of 50 months without symptoms. Six of them (29%) had cardiac events 1-11 months after stopping flecainide. Flecainide-induced Brugada-pattern occurred in 6 carriers (20%), and was not associated with arrhythmia. Sinus node dysfunction was evident in six carriers (20%), and was fully corrected by flecainide in three. In summary, these data suggest that long-term flecainide therapy is relatively safe and effective among LQT3 patients who carry the D1790G SCN5A mutation.