Stellate Ganglion Neuromodulation for the Treatment of Electrical Storm

Stellate ganglion block (SGB) is currently a standard of care option for ventricular tachycardia (VT) storm. However, the evidence to support SBG is derived from non-randomized studies, thus there is a need to test this clinical procedure in an RCT with a sham procedure control. All aspects of the SGB intervention will occur in accordance with local clinical practice, with the exception of control arm participants receiving a sham injection as described below and in the protocol. The study case report forms will be used to collect information related to the local clinical assessments and procedures, as well as participant clinical status and outcomes, but will not dictate local clinical care.

Study summary:

Patients admitted to hospital with VT storm will be approached by study nurse or physician to gain consent for study participation. Study nurse or physician will use web-based randomization (ROME) to allocate participant to intervention or control arm. All participants who give consent will receive aseptic preparation and draping of the site of intervention, scanning with ultrasonography, and marking the site of needle entry with a plastic needle cap, in accordance with local practices. In both arms, a syringe with 10mL 0.5% bupivacaine will be ordered from local clinical supplies and prepared in accordance with institutional practices. The operator will document the intervention delivered in a dedicated case report form. All patients will undergo continuous ECG/telemetry monitoring and ICD interrogation (if applicable) per standard clinical care, for 72 hours following SGB.

SGB Arm:

SGB will be performed according to local practice. Local anesthesia will be delivered subcutaneously prior to the procedure. SGB typically occurs under dynamic ultrasound guidance. Once a landmark for the SGB is identified (e.g., the C6 anterior tubercle), 10 mL of 0.5% bupivacaine will be injected into the left side of the neck using a 22-25G nerve block spinal needle ventral to the longus colli muscle and beneath the prevertebral fascia. This will be a one-time injection. The efficacy of the block will be assessed qualitatively by the operator at the time of the procedure. Any unused bupivacaine will be discarded. The procedure typically takes approximately 20 minutes.

Sham procedure arm:

The sham-procedure will use the identical preparatory and procedural steps as described for the active arm. The procedure area will be screened off from the patient's view, and all equipment used in both active and sham arms will be identical and visible in the room. The duration of the sham procedure will match that of the active intervention, and communication during the procedure will be standardized for both arms. A small dressing will be applied to the site in both groups to further conceal which intervention was performed. Once the skin is draped and cleaned, control arm participants will have 1 mL of 0.5% bupivacaine injected, subcutaneously only. The operator will image the stellate ganglion using ultrasound but will not inject it. The operator will discard the unused bupivacaine to maintain blinding.

The study database will be hosted within PHRI's secure data centre, and eCRFs, including those pertaining to participant status and outcomes, will be completed by local site research assistants from available local medical records. No participant questionnaires or study-specific research tests or assessments are included in the protocol.

• Stellate Ganglion Block Injection with Bupivicaine (Procedure): SGB will be performed according to local practice. Local anesthesia will be delivered subcutaneously prior to the procedure. SGB should typically occurs under dynamic ultrasound guidance. Once a landmark for the SGB is identified (e.g., the C6 anterior tubercle), 10 mL of 0.5% bupivacaine will be injected into the left side of the neck using a 22-25G nerve block spinal needle ventral to the longus colli muscle and beneath the prevertebral fascia. This will be a one-time injection. The efficacy of the block will be assessed qualitatively by the operator at the time of the procedure. Any unused bupivacaine will be discarded. The procedure typically takes approximately 20 minutes.
• Sham procedure control (Other): The sham-procedure will use the identical preparatory and procedure steps as described for the active arm. The duration of the sham procedure will match that of the active intervention, and communication during the procedure will be standardized for both arms. Once the skin is draped and cleaned, control arm participants will have 1 mL of 0.5% bupivacaine injected, subcutaneously only. The operator will discard the unused bupivacaine to maintain blinding.

Primary outcomes

• Time to First Ventricular Tachycardia/Ventricular Fibrillation [72 hours]: The primary outcome is the time to first recurrence of sustained VT/VF during the first 72 hours after randomization, following a 15-minute blanking period post intervention.

Sex: All, ages: 18 Years to any

Inclusion Criteria:

1. Age ≥18 years
2. ≥3 VT/VF episodes within 24 hours (including appropriate shock or antitachycardia pacing (ATP) terminated events) VT/VF episode definition: ventricular tachyarrhythmia episode ≥30 seconds in duration (VT or VF) requiring intervention regardless of duration, as captured on telemetry, ECG or device intracardiac electrogram.
3. <12 hr since last VT/VF episode

Exclusion Criteria:

1. Standard clinical contraindications to nerve block (e.g., overlying site infection/allergy to the drug, cervical mass or history of neck cancer in the anticipated needle trajectory, others)
2. VT storm secondary to underlying ion channelopathies (LQTS, SQTS, Brugada, CPVT, or CRDS)
3. History of cardiac transplant or cardiac sympathetic denervation (CSD)
4. Platelet count <50,000 /µL
5. VT/VF occurring in the setting of acute coronary syndrome prior to revascularization
6. VT storm due to reversible causes (metabolic, drug mediated, etc.)
7. Inability to obtain consent (from patient OR substitute decision maker)