First-in-man study yields promising results for saline-enhanced radio frequency VT ablation

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Douglas Packer

A first-in-human multicentre trial using in-catheter, heated saline-enhanced radio frequency (SERF) ablation for patients with ventricular tachycardia (VT) has reported that the technique showed complete acute and satisfactory mid-term control of difficult VTs, which had failed one to five prior ablations and drug therapy.

The findings of the first-in-man feasibility trial were published in a paper in Circulation: Arrhythmia and Electrophysiology, in a paper authored by Douglas L Packer (Mayo Clinic, Rochester, USA).

The technique involves needle ablation using in-catheter, heated, saline-enhanced, radio frequency energy to substantially increase heat transfer, compared to conventional ablation methods. The process produces deeper, controllable lesion scars at sites inside the heart muscle, according to researchers. The catheter can accurately control the ablation size and treat tissue that is deeper in the heart wall, which is where life-threatening arrhythmias that cause ventricular tachycardia are often found, it is claimed.

Therapies of medication and traditional ablation may not be enough to prevent ventricular tachycardia, and many patients also have an implantable cardioverter-defibrillator (ICD) to address arrhythmias. While an ICD shock corrects the heart’s rhythm, it does not prevent arrhythmia. In the trial, researchers used several methods to directly eliminate abnormal heart tissue that causes life-threatening rhythm.

“This preliminary trial is important because it suggests that there is a new way to treat problematic ventricular tachycardia by reducing or eliminating the shocks that ICDs deliver. It appears to be effective in achieving this goal,” says Packer the first author and principal investigator of the study. “For clinicians, it provides hope that treatment in the electrophysiology lab may be effective, even if other treatments failed. For patients, it provides hope that their quality of life can be improved.”

The catheter was developed by Michael Curley of Boston-based Thermedical, with funding from the National Institutes of Health (NIH). Curley is senior author of the research findings published in Circulation: Arrhythmia and Electrophysiology.

In the trial, 32 participants from six centres underwent needle electrode ablation. Each had experienced multiple episodes of VT that did not respond to drug therapy after an ICD was implanted and standard ablation was done. These patients had about 45 shocks from their defibrillator in the six months before their procedure.

For 31 of these 32 patients, their clinical VT was eliminated immediately at the end of the procedure. Device therapies, such as shock or pace regulation, were reduced by 89% during the five-month follow-up period. Five patients in this high-risk group had complications, primarily in the earlier procedures.

“Patients need better treatments for ventricular tachycardia,” says Emily Tinsley, program officer in the Heart Failure and Arrhythmias Branch of the Division of Cardiovascular Sciences in the National Heart, Lung, and Blood Institute, part of the NIH. Tinsley was not a member of the study team. “While more research is needed to confirm the findings, this trial gives us preliminary information about a promising new technology for treating this condition.”

Packer says the next step in this research is a larger clinical trial with approximately 150 patients to prove the findings and demonstrate the safety of the new SERF technology.


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