Role of chronic, long-term intravenous lidocaine in the clinical management of patients with malignant type 3 long QT syndrome.

ABSTRACT Background Type 3 long QT syndrome (LQT3) is caused by pathogenic, gain-of-function variants in SCN5A leading to a prolonged action potential, ventricular ectopy, and torsades de pointes. Treatment options include pharmacotherapy, cardiac denervation, and/or device therapy. Rarely, patients with malignant LQT3 require cardiac transplantation. Objective To evaluate the role of chronic, continuous intravenous (IV) lidocaine as a therapeutic option for select patients with LQT3 refractory to standard therapy. Methods We performed a retrospective review of patients evaluated and treated at Mayo Clinic and identified 4/161 (2.5%) LQT3 patients who were refractory to standard therapies and therefore treated with IV lidocaine. Results There were 4 patients (2/4 female). The median age at first IV lidocaine infusion was 2 months (IQR=1.5-4.8 months) and median cumulative duration on IV lidocaine was 11.5 months (IQR=8.7-17.8 months). The main indication for IV lidocaine in all patients was persistent ventricular arrhythmias. Prior to IV lidocaine, all patients received an implantable cardioverter-defibrillator and while on intermittent IV lidocaine, all patients underwent bilateral cardiac sympathetic denervation. Additionally, 2 patients had cardiac ablation for premature ventricular complexes. In all patients, lidocaine infusion resulted in a significant reduction of LQT3-triggered cardiac events. The main side effects of IV lidocaine observed were dizziness (n=2) and seizures (n=2). During follow-up, 3/4 patients underwent an orthotopic cardiac transplant. The remaining patient continues to receive IV lidocaine bolus for rescue as needed. Conclusion For patients with LQT3 who are refractory to standard treatment, chronic IV lidocaine infusion can be used as a potential ‘bridge-to-transplant’.