Cardiac transplantation in children and adolescents with long QT syndrome

Background: Long QT syndrome (LQTS) is a potentially lethal, yet highly treatable, cardiac channelopathy. Cardiac transplantation has been reported anecdotally for patients with severe LQTS refractory to standard therapies. Objective: The purpose of this study was to evaluate the incidence of and risk factors for cardiac transplantation in children evaluated and treated in an LQTS specialty center. Methods: This was a retrospective review of 349 children with LQTS (mean age at diagnosis, 8.0 ± 5.7 years; mean corrected QT interval, 469 ± 51 ms; long QT syndrome type 1 [LQT1] in 46%, LQT2 in 31%, and LQT3 in 9%) evaluated from 2000 to 2013. A subset analysis was performed on patients referred for cardiac transplantation. Results: Only 3 patients (0.9%; all LQT3; 2 female) underwent cardiac transplantation at ages 4, 11, and 17 years. Overall, 90 of 349 (26%) were symptomatic (exhibited LQTS-associated cardiac events) before LQTS diagnosis, including those who ultimately underwent transplant. Age at sentinel event was associated with transplantation (3 of 26 [12%] with an event at <1 year of life were transplanted vs 0 of 64 with an event after age 1; P = .02). Genotype was also a risk factor (3 of 32 patients with LQT3 were transplanted [9.4%] vs 0 of 270 patients with LQT1 or LQT2; P = .001). Before transplant, all patients had recurrent ventricular fibrillation-terminating shocks despite combination drug therapy and bilateral sympathetic denervation. All transplanted patients are alive at follow-up. Conclusion: Cardiac transplantation is seldom necessary for the management of LQTS. However, patients with LQT3 and in utero/neonatal expressivity are at higher risk of treatment failure and refractory ventricular arrhythmias with standard therapy, and cardiac transplantation should be considered for this malignant subset of LQTS.