The concomitant treatment with antiarrhythmic drugs do not influence the efficacy of percutaneous stellate ganglion block in patients with electrical storms. New insights from the STAR study

Background Percutaneous stellate ganglion block (PSGB) proved effective when provided on top of standard therapy in patients with electrical storm. Limited evidence suggests its use even before intravenous (i.v.) antiarrhythmic drugs (AAD) but there are no data about its efficacy in patients completely free from antiarrhythmic therapy. Purpose our aim was to assess PSGB effectiveness according to the type of ongoing antiarrhythmic therapy at the time of the PSGB. Methods we considered all the patients enrolled in the multicentre observational STAR study (ClinicalTrials.gov ID NCT05720936) from January 2017 to April 2024. We categorised the procedures into three groups: group1: no oral and no i.v. AADs; group 2: oral chronic AADs or acute i.v. AADs; group 3: both chronic oral and acute i.v. AADs. We compared the number of treated arrhythmias (VAs) between 12 h before and after each procedure and the percentage of procedures with a complete arrhythmic suppression in the 12 hour after PSGB in the three groups. A logistic regression model was used to assess the association of the type of arrhythmias and the probability of having a complete arrhythmic suppression. Results We enrolled 298 patients (median age 68, IQR 58-77 years, 40% with ICD, mean LVEF 30% IQR 20-40%), manly males (246,87%). They received a total of 432 procedures: 31 (7%) in group 1; 256 (59%) group 2 and 145 (34%) in group 3. The number of treated ventricular arrhythmias in the 12 hours before the procedure was similar in the three groups (group 1: 4 (IQR 1.2-8.5); group 2: 5.5 (IQR 3 -11); group 3: 3 (IQR 1-10), p= ns). There was a statistically significant reduction of treated VAs in all the three groups (figure 1) and the extent of the reduction of treated VAs comparing 12 hours before and after was similar in the three groups [group 1: 4 (IQR 1-7), group2: 4 (IQR 1-9) and group 3: 3 (IQR 0-8), p=0.4)]. The percentage of procedures with a complete VAs suppression at 12 hours was larger in the first group (group 1: 82%, group 2: 61%, group 3: 72%, p<0.001). At logistic regression the concomitant antiarrhythmic therapy was not associated with the probability of a complete suppression of treated VAs at 12 hours [group 1 vs group 2 and 3: OR 2.5 (95%CI0.9-6.7), p=0.07]. Conclusion this study highlights that PSGB may be effective even if not preceded by any antiarrhythmic therapy and sheds light on its real antiarrhythmic effect. Our results may suggest an early use preventing arrhythmias to become refractory.