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UNTOUCHED: Subcutaneous ICD effective for primary sudden cardiac death prevention
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SAN FRANCISCO — A subcutaneous implantable cardioverter defibrillator was safe and effective in a higher-risk population than had been evaluated in previous trials, according to results of the UNTOUCHED study.
Lucas V. Boersma, MD, PhD, FESC, professor of Innovative Transcatheter Treatments for Cardiac Arrhythmias at the University of Amsterdam's Faculty of Medicine and head of the cardiology research and development department at St. Antonius Ziekenhuis, Nieuwegein, the Netherlands, and colleagues evaluated 1,103 patients (26% women) implanted with the device (Emblem S-ICD, Boston Scientific), which was designed without transvenous leads to avoid lead-related complications.
All patients had left ventricular ejection fraction of 35% or less, did not have prior ventricular fibrillation or ventricular tachycardia and were indicated for an ICD for primary prevention of sudden cardiac death.
For a presentation at the Heart Rhythm Society Annual Scientific Sessions and publication in HeartRhythm, Boersma and colleagues characterized the cohort and reported acute outcomes. The primary outcome, to be presented later, is inappropriate shock rates at 2 years.
“In the beginning, there were issues with infection, and people didn’t know in which patients this device was the best option,” Boersma told Cardiology Today. “The bulk of patients who need ICDs have low ejection fraction and require primary prevention, but these patients were underrepresented in the registries we had. So UNTOUCHED was designed to test the device specifically in a population with a primary prevention indication and low ejection fraction to show the efficacy and safety of this device in the conventional population.”
The patients in this cohort were older and had more comorbidities than those in previous studies of the device, Boersma said.
According to the researchers, the 30-day rate of freedom from complications was 95.8%, and most complications were periprocedural or happened within the first 24 hours.
The most common complication category was healing/pain management (1.9%), including 0.6% who had a device-related infection, and there were no multivariate predictors of complications, Boersma said.
Mean procedure time was 58.1 minutes, and the procedures took longer in patients with obesity, black patients, younger patients, those implanted in Europe and those who had the three-incision technique instead of the two-incision technique, he said.
“It was nice to show that the two-incision technique was faster and the outcomes with respect to safety were the same,” Boersma said in an interview. “It was interesting that the North American sites were quicker than the European sites. It may have something to do with that in the U.S., most patients are treated under general anesthesia, so you don’t have to worry about the patient’s pain or comfort.”
Successful conversions occurred in 99.2% of patients, with 93.5% needing 65 joules or less, according to the researchers.
Higher BMI (P = .002) and presence of diabetes (P = .03) were predictors of conversion failure at 65 joules, Boersma said.
Rates of conversion efficacy and freedom from complications were similar to previous cohorts, he said.
“These patients do not do worse with complications, which is a good thing given that they are older and have more comorbidities,” Boersma told Cardiology Today. “We confirmed that the device works just as well in this population as in other populations in the first 30 days, and we will have to wait and see what happens in the longer term.” – by Erik Swain
Reference:
Boersma LV, et al. LBCT02-05. Presented at: Heart Rhythm Society Annual Scientific Sessions; May 8-11, 2019; San Francisco.
Boersma LV, et al. Heart Rhythm. 2019;doi:10.1016/j.hrthm.2019.04.048.
Disclosure: The study was funded by Boston Scientific. Boersma reports he consults for Boston Scientific and Medtronic but the fees go to his institution.
Perspective
Back to TopDaniel J. Cantillon, MD, FACC, FHRS
The UNTOUCHED study looked at a large number of patients, primarily in the U.S. and Europe, that underwent subcutaneous ICD implantation for primary prevention against sudden cardiac death. The major finding was that the 30-day rate of freedom from complications was about 96%, a very favorable result. The study shows the S-ICD continues to be a very robust platform for SCD coverage in a very sick primary prevention population with low EF.
The study also showed some interesting disparities in how the procedure is done. About one-third had moderate sedation and two-thirds general anesthesia. There was variability in performance of defibrillation testing. The other notable aspect of the study was that BMI was a predictor of failed defibrillation. It may be more difficult in a larger patient to get the equipment positioned for optimal defibrillation effectiveness. We need to get the device successfully implanted in the correct plane.
Perspective
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Theofanie Mela, MD
This study confirms what we know from clinical practice: The use of the S-ICD is efficacious and safe in sicker populations than had been enrolled in past published studies. One criticism of the older trials was that the patient population was younger and healthier than those typically seen in clinical practice. It was unclear whether this technology would apply to the general ICD population that we deal with on a daily basis. With this trial, we are confirming that the S-ICD is a useful, efficacious and safe technology for these patients.
This study will help make this technology more widely used by electrophysiologists. It is still one of the options we have when patients require a defibrillator. Therefore, every time an electrophysiologist has to choose what device to select for the patient, they will have to weigh the pros and cons of this technology.
This study will give us a lot more information in subsequent analyses beyond this presentation, particularly with regard to subgroups.
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