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Noninvasive radioablation reduces burden in ventricular tachycardia
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Patients with ventricular tachycardia who were treated with a catheter-free, electrophysiology-guided cardiac radioablation technique had dramatically fewer episodes at 1 year, according to a study published in The New England Journal of Medicine.
Phillip S. Cuculich, MD, assistant professor of medicine in the division of cardiovascular disease at Washington University School of Medicine in St. Louis, and colleagues evaluated data from five patients (mean age, 66 years; one woman) with ventricular tachycardia, an implantable cardioverter defibrillator and structural heart disease. Those who previously had a left ventricular assist device implanted were excluded.
Study workflow
Patients underwent various tests, including ECG, cardiac imaging and a planning CT scan, before they were treated with stereotactic body radiation therapy with use of an image-guided, radiotherapy-equipped linear accelerator (TrueBeam, Varian Medical Systems) to acquire images of the thorax.
After treatment, ICDs were reprogrammed and monitored throughout follow-up, which was conducted periodically for 1 year. Antiarrhythmic medications were potentially weaned off during follow-up.
Cardiac adverse events were monitored by echocardiogram at baseline and at 1, 6 and 12 months after treatment. Thoracic events were assessed by chest CT at baseline and at 3 and 12 months.
The mean time for noninvasive ablation was 14 minutes.
Patients had 6,577 episodes of ventricular tachycardia 3 months before treatment, which decreased to 680 episodes during the blanking period of 6 weeks after treatment. From 6 weeks to 1 year after treatment, patients had four episodes of ventricular tachycardia.
The relative reduction from baseline to 1 year was 99.9%. All patients had a reduction in ventricular tachycardia episodes.
Effects on LVEF, lung
LV ejection fraction increased by 6 percentage points (range, –2 to 22) at 1 year.
At 3 months, patients had inflammatory changes in the adjacent lung, which was resolved at 1 year. The changes were typical of thoracic stereotactic body radiation therapy, the researchers wrote.
“Because of the novelty of noninvasive radioablation, its potential for harm and the limited number of patients who were included in this analysis, this procedure should not be considered to be suitable for clinical use, pending the results of further research studies,” Cuculich and colleagues wrote. “Furthermore, there are well-described late toxic effects of radiotherapy to the heart for large-field fractionated-dose treatments, as has been reported in the treatment of lymphoma and breast cancer.”
Episodes of [ventricular tachycardia] predict increased rates of death and hospitalization for heart failure despite prompt ICD termination of the arrhythmia,” Roy M. John, MBBS, PhD, associate professor of medicine at Vanderbilt University Medical Center in Nashville, and William G. Stevenson, MD, professor of medicine at Vanderbilt University Medical Center and a Cardiology Today Editorial Board Member, wrote in a related 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.” – by Darlene Dobkowski
Disclosures: Cuculich reports he received grants from the Barnes-Jewish Hospital Foundation and has a patent related to the study pending. John reports he received personal fees from Abbott. Stevenson reports he received personal fees from Boston Scientific, other support from St. Jude Medical/Abbott and has been issued a patent for a method to ablate with a needle electrode. Please see the study for all other authors’ relevant financial disclosures.
Perspective
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Bruce D. Lindsay, MD
This is an extremely important innovation for the treatment of patients with life-threatening ventricular tachycardia that is refractory to medical therapy, cannot be ablated and causes recurrent ICD shocks. The study demonstrates that noninvasive ECG imaging can be used to identify the complex circuits related to ventricular tachycardia and guide noninvasive stereotactic body radiation. This preliminary work shows a dramatic reduction in the number of episodes or complete elimination of ventricular tachycardia.
This has very important clinical implications for major centers where patients with complex arrhythmias are referred when standard approaches fail. I view it as a major breakthrough in the treatment of these difficult arrhythmias. We have discussed the concept of targeting radiation for treatment of arrhythmias, but this is the first time this approach has been used successfully.
This pilot study involved five highly selected patients. Further study is needed to assess the efficacy and safety of the technique.
This is an example of how a multidisciplinary approach combined with advanced engineering can be used to solve difficult problems.
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