Long Term Prophylactic Therapy of Congenital Long QT Syndrome Type III (LQT3) With Ranolazine

Inclusion Criteria: * Long QT patients with genetic confirmation of carrier-status for the D1790G mutation in the SCN5A gene * Corrected QT interval \> 460 msec Exclusion Criteria: * Need for therapy with medications that are potent or moderately potent CYP3A inhibitors (such as ketoconazole, diltiazem, verapamil, macrolide antibiotics or HIV protease inhibitors)