The role of mexiletine in the management of long QT syndrome.

Congenital long QT syndrome (LQTS) is a hereditary cardiac disorder characterized by QT-interval prolongation and T-wave abnormalities on electrocardiogram (ECG), and is associated with an increased risk of torsade de pointes and sudden cardiac death. Beta-blocker medication is effective in most patients except those with a very slow heart rate. Increased late sodium currents (INa-L) can result in bradycardia-dependent QT prolongation. Mexiletine, an inhibitor of INa-L, is not only effective in treating type-3 LQTS, but also shows the promise in managing LQTS patients of other genotypes with markedly prolonged QT interval at slow heart rates.