Efficacy of percutaneous stellate ganglion block according to ventricular arrhythmia cycle length: A post hoc subanalysis of the STAR study

Background: Data on the predictors of percutaneous stellate ganglion block (PSGB) efficacy in electrical storm are scanty. Objective: We aimed to assess whether PSGB efficacy is influenced by the arrhythmia type and cycle length before the procedure. Methods: This is a subanalysis of the multicenter STAR study. The population was stratified into 3 groups according to the median cycle length of the latest ventricular arrhythmia before PSGB: ventricular fibrillation (VF), fast ventricular tachycardia (VT), and slow VT. The primary outcome was the number of treated arrhythmic episodes (with antitachycardia pacing or direct current shocks) in the hour immediately after PSGB compared with the hour before. Results: We considered 139 PSGBs from 112 patients divided into VF (51 procedures), fast VT (44 procedures, VT cycle <375 ms), and slow VT (44 procedures, VT cycle ≥375 ms). The number of treated arrhythmic episodes in the hour after every PSGB was significantly lower compared with the hour before in all groups (VF: 0 [0-1] vs 5 [2-8], P < .001; fast VT: 0 [0-0] vs 1 [0-6.5], P < .001; slow VT: 0 [0-0] vs 1 [0-4.5], P = .001). In analyzing the reduction of the number of antitachycardia pacing sequences or direct current shocks from the hour before to the hour after PSGB, a significant trend was observed across the groups (Jonckheere-Terpstra trend P < .001), and a significant difference was observed in comparing slow VT vs VF and fast VT vs VF but not in comparing slow VT vs fast VT. VF was independently associated with the probability of reduction of treated events after PSGB. Conclusion: PSGB is an effective treatment of electrical storm in patients with all types of ventricular arrhythmias. However, its effectiveness was more pronounced in patients with VF.