Management of an Electrical Storm in a Patient With Long Qt Syndrome Type 2: Combining Beta–blockers and Overdrive Pacing

Long QT syndrome (LQTS) is a genetic channelopathy with a prevalence of approximately 1 in 2000. Type 2 (LQT2), caused by KCNH2 gene variants affecting the IKr current, is particularly prone to life–threatening arrhythmias triggered by sudden noises, emotional stress, or bradycardia. In the acute setting of an electrical storm, management remains a critical challenge. A 26–year–old female with a known KCNH2 mutation, already under treatment with Nadolol 80 mg daily, presented with an electrical storm (Figure 1). The patient had a concomitant diagnosis of epilepsy treated with Vimpat and Clobazam; therefore, an implantable loop recorder (ILR) had been previously inserted to evaluate a potential arrhythmic cause for her convulsive syncope. This device was fundamental in the diagnosis, as it documented multiple episodes of sustained ventricular tachycardia and a 2–minute episode of ventricular fibrillation, confirming the cardiac origin of her crises. At admission, the surface ECG showed a markedly prolonged QTc of 690 ms and notched T waves (Figure 2). Initial laboratory results showed a potassium level of 3.9 mmol/l. Acute stabilization was initiated with intensive electrolyte replacement and intravenous Esmolol. To address the electrical instability, a temporary external atrial pacemaker was programmed for overdrive pacing at 90 bpm. This strategy served as a crucial bridge to manage the acute phase, successfully suppressing Torsades de Pointes (TdP) and allowing for the safe re–introduction and up–titration of her Nadolol to 80 mg twice daily. The patient subsequently underwent successful implantation of a dual–chamber cardioverter–defibrillator (ICD). To prevent the bradycardia–induced pause–dependent prolongation of the QT interval typical of LQT2, the device was programmed with a base rate of 70 bpm. This higher heart rate prevents the long–short sequences that initiate TdP while allowing the patient to maintain the necessary high–dose beta–blockade. At discharge, the QTc had significantly shortened to 480 ms (Figure 3).