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Focused Radiation May Nearly Erase Ventricular Tachycardia

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Ablation for ventricular tachycardia may be achieved by noninvasive means with cardiac radiation, a case series showed.

The catheter-free radioablation technique used by Phillip Cuculich, MD, of Washington University School of Medicine in St. Louis, and colleagues resulted in a 99.9% reduction of ventricular tachycardia episodes among five study subjects, as recorded by implantable cardioverter-defibrillators (ICDs).

Participants went from experiencing 6,577 episodes in the 3 months before treatment to just four during 46 patient-months after the blanking period, the investigators reported online in the New England Journal of Medicine.

Cuculich’s group said that “if a noninvasive approach to ablation of ventricular tachycardia is shown to be safe and effective, it would be a potentially important therapeutic advance.”

Radioablation took 14 minutes on average. Serial cardiac and thoracic imaging showed no pericardial effusions, and the investigators observed no adverse effects on ICD system performance, lead thresholds, or lead impedances after the procedure was done. Mean left ventricular ejection fraction did not fall with treatment.

What’s more, patients reported no pulmonary symptoms and had zero complications during treatment or the index hospitalization. Some mild inflammatory changes in the adjacent lung were observed at 3-month follow-up and were resolved by 1 year.

The 6-week blanking period immediately after radioablation racked up 680 episodes of ventricular tachycardia among participants.

Of the four patients alive at 12 months, three were not on any antiarrhythmic medication (one had gotten an additional catheter ablation 4 weeks after radioablation). The sole death was the result of a stroke 3 weeks after treatment; it remained unclear if the radioablation had anything to do with that fatal stroke.

“The potential late effects of high-dose stereotactic body radiation therapyexclusively to focal areas of previously injured heart are unknown,” the authors acknowledged, noting that the amount of heart tissue subjected to radiation is big enough that the procedure may have unintended effects on specialized cardiac structures such as papillary muscles, coronary arteries, and valves.

“Early and late toxic effects need to be defined, including the risk of late cancer if this method is applied to patients with milder heart disease who can be expected to have long post-procedural survival,” wrote Roy John, MBBS, PhD, and William Stevenson, MD, both of Vanderbilt University Medical Center in Nashville, in an accompanying editorial.

“Although ventricular tachycardia is probably a marker for the severity of heart disease and declining cardiac function, it has also been suggested that the ventricular tachycardia event itself and ICD shocks exacerbate cardiac decline. Whether better arrhythmia control in patients with ICDs will improve survival is an important question that will be easier to answer when more effective ablation therapies become available,” according to John and Stevenson.

The five high-risk patients in this study all had refractory ventricular tachycardia despite having taken at least two antiarrhythmic medications and having undergone at least one catheter ablation procedure.

Radioablation was delivered as a single fraction of 25 Gy while patients were awake. Operators used the TruBeam image-guided radiotherapy-equipped linear accelerator equipped with cone-beam CT to acquire images of the thorax, which can be directly registered to the planning CT. “This procedure results in accurate alignment of the heart and target volume without the need for invasive placement of a fiducial marker,” according to Cuculich and colleagues.

Their next step is ENCORE-VT, a prospective phase I/II trial of stereotactic body radiation therapy for ventricular tachycardia treatment, which is underway.


The above post is reprinted from materials provided by: MedpageToday

 

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