Extravascular ICD safe, able to terminate ventricular arrhythmias
The novel extravascular implantable cardioverter defibrillator was implanted safely and was able to detect and terminate ventricular arrhythmias, according to a premarket study presented at the European Society of Cardiology Congress.
“The extravascular defibrillator is the next generation of implantable defibrillator,” Ian Crozier, MD, clinical cardiologist at Christchurch Hospital, New Zealand, who presented the findings, told Healio. “It addresses the limitations of the currently available [transvenous] devices ... which have a lead that goes through the veins and down to the heart, [which causes] a lot of complications both in the short and long term. The subcutaneous defibrillator ... doesn’t have a lead into the heart, but it has a lot of other disadvantages. It can’t provide pacing of the heart, apart from limited post-shock pacing. Also, it’s a very large, bulky, uncomfortable device. The extravascular defibrillator avoids having a lead into the heart, but because the lead is put closer to the heart, under rather than over the sternum, we have a device that can provide antitachycardia pacing ... and the device is much smaller [and] addresses the limitations of both kinds of existing defibrillators.”
For the Extravascular ICD Pivotal Study, a single-group, prospective, nonrandomized, premarket approval trial, Crozier and colleagues enrolled 356 patients, all of whom had a class I or IIa indication for an ICD. Among the cohort, 316 had an attempt at implantation with the extravascular ICD (Medtronic). The results were simultaneously published in The New England Journal of Medicine.
The primary efficacy endpoint was successful defibrillation at implantation, and was considered to be met if the lower boundary of the one-sided 97.5% CI exceeded 88%, a goal based on performance of transvenous ICDs. The primary safety endpoint was freedom from major system- or procedure-related complications at 6 months, and was considered to be met if the lower boundary of the one-sided 97.5% CI exceeded 79%.
Of the 302 patients who completed the defibrillation testing protocol and in whom ventricular arrhythmia could be induced, the percentage with successful defibrillation was 98.7% (lower boundary of one-sided 97.5% CI, 96.6%; P for comparison with performance goal < .001), the researchers found.
“That’s a very, very high rate,” Crozier told Healio.
Among the 316 patients with an implantation attempt (mean age, 54 years; 25% women), 94.6% were discharged with a working ICD system, according to the researchers.
The Kaplan-Meier estimate of the percentage of freedom from major system- or procedure-related complications at 6 months was 92.6% (lower boundary of one-sided 97.5% CI, 89%; P for comparison with performance goal < .001), Crozier and colleagues found.
There were no major intraprocedural complications, and at 6 months, there were 25 major complications in 23 patients (7.3%), according to the researchers.
Crozier and colleagues assessed the success rate of antitachycardia pacing with generalized estimating equations, and the rate was 50.8% (95% CI, 23.3-77.8).
Inappropriate shocks occurred 118 times for 81 arrhythmic episodes in 29 patients.
At a mean of 10.6 months, eight systems were explanted.
“The next-generation device can be implanted safely, it provides effective therapy and it provides both antitachycardia pacing and defibrillation therapy,” Crozier told Healio.
The device is not yet approved for commercial use in the United States.
Reference:
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Crozier I, et al. Latest science in ICD and sudden cardiac death. Presented at: European Society of Cardiology Congress; Aug. 26-29, 2022; Barcelona, Spain (hybrid meeting).
