Stellate ganglion (SG) phototherapy using a low-level laser is a promising rescue therapy for patients with refractory ventricular arrhythmias, report clinicians from Japan.
In a small study, SG phototherapy decreased sympathetic activity in healthy volunteers and effectively suppressed drug-refractory ventricular arrhythmias in some patients with electrical storm (ES).
“SG phototherapy using low-level laser is safe, noninvasive and easy to perform” principal investigator Kyoko Soejima, MD, professor and chair of cardiovascular medicine, Kyorin University Hospital, Tokyo, told theheart.org | Medscape Cardiology.
SG phototherapy does not require local anesthesia, can be applied to patients with ES who are in poor general condition and too unstable to undergo ablation, and can “buy time before patients can go to more invasive but effective therapy,” Soejima said.
The study was published online June 30 in the Journal of the American College of Cardiology: Clinical Electrophysiology.
A Bridge to More Effective Therapy?
Patients with ES experience clustered episodes of ventricular arrhythmias (VA) that harm quality of life and prognosis. The management of ES usually includes treatment with amiodarone and beta blockers, deep sedation, and catheter ablation. Modulation of the autonomic nervous system has been shown to be an effective adjunctive therapy for ES.
In a two-part study, Soejima’s group first determined the effects of SG phototherapy on the autonomic nervous system in 20 healthy volunteers (10 males; mean age, 41 years), mainly colleagues, nurses, and physicians working at Kyorin University.
They underwent a 10-minute session of SG phototherapy using a low-level laser on both sides of the neck, close to the SG, repeated twice a week for 4 weeks (eight sessions).
No adverse events were observed after SG phototherapy in any volunteer.
SG phototherapy acutely reduced sympathetic activity in the volunteers, as evidenced by significantly reduced low-frequency power/high-frequency power and noradrenaline, the researchers report.
No significant changes in heart rate, blood pressure, PR interval, QRS duration, or QTc interval were observed, and changes in heart rate variability (HRV) appeared temporary, as HRV levels had returned to baseline at the 3-month follow-up.
In the clinical pilot study, SG phototherapy was applied to 11 patients with ES and frequent episodes of ventricular tachycardia (VT)/ventricular fibrillation (VF) despite pharmacologic therapy and/or catheter ablation.
The duration and type of the SG phototherapy varied by patient, from 4 and 22 days, and xenon, near-infrared light, or both was administered at the discretion of the treating physicians.
SG phototherapy was considered successful if a patient did not require implantable cardioverter-defibrillator (ICD) shock or antitachycardia pacing therapy within 72 hours after the first session.
In seven of the 11 patients, ES was immediately suppressed with SG phototherapy and ICD therapy was not required in the 72 hours after the initial SG phototherapy session.
“However, based on the recurrence of ES in patients without maintenance therapy, it was determined that there might be a time limit to the efficacy of SG phototherapy,” the researchers report.
Among the seven responders, two had VA recurrence, albeit with less burden and controlled by additional medication. In the remaining four patients, a “limited effect” from SG phototherapy was observed; two patients had reduced arrhythmia frequency without total suppression of ES and two remained in ES.
On average, SG phototherapy decreased the VA burden from 8.0 episodes per day to 2.0 per day (P = .066).
The researchers note that in one patient, SG phototherapy was performed daily for 10 minutes for 22 days, followed by monthly maintenance phototherapy.
This patient experienced only two VF episodes in the 24 months after treatment, at which time he underwent catheter ablation. After the successful VT ablation, the patient continued monthly SG phototherapy and has been free from VT/VF for 52 months.
As in the healthy volunteers, no adverse effects were observed in the clinical sample.
This pilot study shows that SG phototherapy “may be a safe and effective adjunctive therapy for some patients with ES, but its long-term efficacy remains unknown,” Soejima and colleagues write.
“I think anyone who is preferably managed noninvasively with autonomic modulation (not stellate gangliectomy or SG block) can be a candidate for SG phototherapy,” Soejima told theheart.org | Medscape Cardiology.
She said SG phototherapy can serve as a bridge to catheter ablation or SG sympathectomy and its chronic use might reduce ES recurrence, but further studies are needed to confirm this.
The investigators are currently enrolling patients with ES in a larger study.
Reached for comment, Davendra Mehta, MD, PhD, cardiac electrophysiologist, Mount Sinai Morningside, New York City, noted that the principal investigator of the study is a “very well respected electrophysiologist.”
“Stellate ganglion resection has been shown to be useful in patients with resistant ventricular arrhythmias or electrical storm and it appears from this report that (SG phototherapy) might also be helpful in electrical storm,” Mehta said.
However, “one study always means nothing, and the study is in a very small number of patients, so we clearly need more information and this needs to be confirmed,” he said.
Following this pilot study in Japan, “somebody will obviously reproduce the study here and see if it works or not,” Mehta added.
Also weighing in on the study, Stephen Winters, MD, cardiac electrophysiologist and director, Cardiac Rhythm Management Program, Atlantic Health-Morristown Medical Center, New Jersey, said these “unique findings raise the possibility of a novel, noninvasive manner to treat potentially life-threatening ventricular arrhythmias.”
“The alterations in heart rate variability and reductions in adrenaline levels documented in healthy control subjects suggest a reduction in sympathetic tone as a result of the phototherapy. While the investigators report a reduction in events in seven of 11 patients with sustained VT, true ability to claim statistical significance is lacking and chance effects cannot be excluded,” Winters noted.
Nonetheless, the findings are “intriguing and certainly hypothesis-generating” and merit larger, well-controlled studies, Winters told theheart.org | Medscape Cardiology.
“Further studies to document whether the technique may be of benefit in treating nonlife-threatening tachycardias, such as inappropriate sinus tachycardia, may also merit consideration,” he added.
The study had no specific funding. Soejima has received honoraria for lectures from Abbott Japan and Medtronic Japan . A complete list of author disclosures is available with the original article. Mehta has no relevant conflicts of interest.
J Am Coll Cardiol EP. Published online June 30, 2021. Full text
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