Percutaneous Stellate Ganglion Block as First Line Treatment in Patients With Electrical Storm: the STAR 2 Study

Electrical storm (ES) is a life-threatening condition characterized by recurrent episodes of ventricular tachycardia (VT) or ventricular fibrillation (VF) requiring anti-tachycardia pacing or defibrillator shocks. Despite advances in management, ES remains associated with high morbidity and mortality, and current pharmacological options are often insufficient or slow-acting.

The STAR 2 study is a multicentre, randomized, open-label, adaptive superiority trial designed to evaluate whether percutaneous stellate ganglion block (PSGB) as first-line therapy is superior to intravenous amiodarone in patients with ES. The primary hypothesis is that PSGB administered as initial treatment will result in a higher proportion of patients achieving complete suppression of treated ventricular arrhythmias during the first three hours after treatment compared with intravenous amiodarone.

Adult patients presenting with electrical storm, defined as three or more episodes of fast VT/VF (cycle length \<400 ms) treated by internal or external defibrillator within the preceding 12 hours, including at least one episode in the three hours before randomization, will be eligible for participation. Patients will be randomly assigned in a 1:1 ratio to receive either PSGB or intravenous amiodarone as first-line treatment.

In the intervention arm, patients will undergo left PSGB using a combination of 200 mg lidocaine and 50 mg bupivacaine injected percutaneously at the level of the left stellate ganglion. The procedure may be repeated once within the first three hours in case of arrhythmic recurrence, without exceeding maximum recommended doses. In the control arm, patients will receive intravenous amiodarone according to a standardized protocol consisting of a 300-mg loading dose over 30 minutes followed by 900 mg infused over 18-24 hours.

The primary outcome is the proportion of patients with complete suppression of treated ventricular arrhythmias (defined as VT/VF episodes requiring anti-tachycardia pacing, internal cardioverter-defibrillator shock, or external defibrillator shock) during the first three hours after treatment administration. Secondary outcomes include time to first recurrence of ventricular arrhythmia within three hours, per-patient rate of treated ventricular arrhythmias in the first three and twelve hours after treatment, crossover rate between treatment arms, survival to hospital discharge, and survival at one month. Safety outcomes will include procedure- and drug-related complications and adverse events.

The study plans to enroll up to 180 patients across multiple centres. An adaptive design with pre-specified interim analyses for futility and efficacy will be employed, allowing for early termination if predefined statistical boundaries are crossed. Participants will be followed throughout hospitalization and for 30 days after discharge.

This trial aims to provide robust evidence on the comparative effectiveness and safety of PSGB versus standard antiarrhythmic therapy when used as first-line treatment in patients with electrical storm, potentially supporting a shift in current management strategies.