Effectiveness of Implantable Cardioverter-Defibrillators to Reduce Mortality in Patients With Long QT Syndrome.

Background: The effectiveness of implantable cardioverter-defibrillators (ICDs) on reducing mortality has not been well studied in patients with long QT syndrome (LQTS).

Objectives: This study aimed to assess the survival benefits of ICDs in the overall LQTS population and in subgroups defined by ICD indications.

Methods: This study included 3,035 patients (597 with ICD) from the Rochester LQTS Registry with a QTc ≥470 milliseconds or confirmed LQTS mutation. Using multivariable Cox proportional hazards models, the risk of all-cause mortality, all-cause mortality before age 50 years, and sudden cardiac death (SCD) were estimated as functions of time-dependent ICD therapy. Indication subgroups examined included patients with: 1) nonfatal cardiac arrest; 2) syncope while on beta-blockers; and 3) a QTc ≥500 milliseconds and syncope while off beta-blockers.

Results: During the 118,837 person-years of follow-up, 389 patients died (137 before age 50 years, and 116 experienced SCD). In the entire population, patients with ICDs had a lower risk of death (HR: 0.54; 95% CI: 0.34-0.86), death before age 50 years (HR: 0.29; 95% CI: 0.14-0.61), and SCD (HR: 0.22; 95% CI: 0.09-0.55) than patients without ICDs did. Patients with ICDs also had a lower risk of mortality among the 3 indication subgroups (HR: 0.14; 95% CI: 0.06-0.34; HR: 0.27; 95% CI: 0.10-0.72; and HR: 0.42; 95% CI: 0.19-0.96, respectively).

Conclusions: ICD therapy was associated with a lower risk of all-cause mortality, all-cause mortality before age 50 years, and SCD in the LQTS population, as wells as with a lower risk of all-cause mortality in indication subgroups. This study provides evidence supporting ICD implantation in patients with high-risk LQTS.