Central Illustration.

Reduction of Arrhythmic Events During Treatment With Mexiletine in Patients With Long QT Syndrome Type 3

We observed a significant reduction of the arrhythmic burden in our cohort of consecutive patients with long QT syndrome type 3 treated with mexiletine during matched periods of a median of 35 months. The percentage of patients with arrhythmic events declined from 22% (95% confidence interval [CI]: 7 to 37) to 3% (95% CI: 0 to 9; p = 0.031, A), the mean number of arrhythmic events per patient decreased from 0.43 ± 0.17 to 0.03 ± 0.03 (p = 0.027, B), and the rate of arrhythmic events dropped by 93%, from 10.3 (95% CI: 4.6 to 23) per 100 PY to 0.7 (95% CI: 0.1 to 5.5) per 100 PY (p = 0.0097, C).