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HomeHealthMedicineExtravascular ICD Surpasses Goals in Pivotal Trial

Extravascular ICD Surpasses Goals in Pivotal Trial

BARCELONA – A novel “extravascular” implantable cardioverter defibrillator (ICD) that makes use of substernally positioned electrodes surpassed its prespecified efficacy and security targets within the machine’s pivotal trial with 299 sufferers who obtained an implant.

The outcomes confirmed that the extravascular ICD “provides antitachycardia pacing and low energy defibrillation while avoiding the vascular space” for lead placement, Ian Crozier, MD, stated on the annual congress of the European Society of Cardiology.

“The results are fantastic; they exceeded our expectations,” stated Crozier in an interview, including that he expects the brand new machine to obtain advertising and marketing approval from regulatory companies primarily based on the findings. “This will be the next generation of ICD going forward,” predicted Crozier, an electrophysiologist heart specialist at Christchurch (New Zealand) Hospital.

Moving Beyond Transvenous and Subcutaneous ICDs

Traditional ICDs use transvenous leads, which may trigger vascular harm, are susceptible to steer fracture over time, and may produce critical infections in addition to different potential problems. The U.S. Food and Drug Administration first approved an alternative-design, subcutaneous ICD in 2012 that avoids the necessity for transvenous leads and the dangers they pose. But subcutaneous ICDs have their very own limitations: an lack of ability to supply antitachycardia pacing or power pacing; a restricted capability to supply bradycardia pacing; and an elevated machine measurement with shorter battery life, due to the excessive shock energy wanted for efficient efficiency. These drawbacks have collectively hindered uptake, Crozier stated.


This led to growth of the extravascular ICD – 10 years within the making – which makes use of substernally positioned leads that permit antitachycardia pacing and backup pacing in a tool with the dimensions of and the anticipated battery longevity of a transvenous ICD machine, famous Crozier.

A 98.7% Rate of Arrhythmia Termination at Implant

The pivotal trial’s main efficacy endpoint was profitable defibrillation primarily based on terminating an induced, sustained, shockable ventricular arrhythmia on the time of implantation. The fee was 98.7%, in contrast with a prespecified goal of 88%. All sufferers had a category I or IIa indication for an ICD.

The main security endpoint was freedom from main system- or procedure-related problems at 6 months, which occurred at a fee of 92.6%, in contrast with the examine’s prespecified goal fee of 79%. Both targets have been derived from the historic charges of ICDs with transvenous leads.

Simultaneously with Crozier’s report on the congress, the outcomes additionally appeared online within the New England Journal of Medicine.

Although the pivotal examine met each prespecified endpoints, the proof has limitations that make it seemingly that regulatory our bodies will search further information, commented Fred Kusumoto, MD, director of coronary heart rhythm providers for the Mayo Clinic in Jacksonville, Fla.

Short Follow-Up; Questions Remain

“Follow-up was relatively short, less than a year,” and “questions remain” concerning the extravascular ICD’s efficiency, Kusumoto stated in an interview. “Inappropriate shocks occurred in nearly 10% of patients after 11 month follow-up,” he famous, and likewise cited the 29 sufferers who wanted revisions together with two instances with lead fractures.

“The extravascular lead strategy has an advantage over transvenous systems because of the lower risk for extraction or explant,” and it additionally supplies the antitachycardia pacing that is not out there with subcutaneous ICDs, he granted. But within the new examine, antitachycardia termination was delivered to solely 10 sufferers and had “reasonable” effectiveness by resolving 70% of those episodes. “Wide adoption by clinicians will depend on results from larger studies with longer follow-up,” Kusumoto maintained. He additionally needed to see affirmation of the convenience of lead removing after longer intervals of implantation.

Implantation “Is Not Difficult”

The trial ran at 46 websites in 17 international locations throughout September 2019 to October 2021. It enrolled sufferers with a category I or IIa indication for an ICD, excluding sufferers with a previous sternotomy or want for power pacing, and people unable to endure defibrillation testing.

Clinicians tried an implantation in 316 sufferers and had profitable placement in 299 (314 had profitable placement of their substernal leads), with 292 having a practical machine after 6 months, and 284 finishing their deliberate 6-month follow-up. The median process time was 66 minutes, together with the time for defibrillation testing.

All of the cardiologists who did the implants had obtained a full day of coaching previous to performing the process. “This is not a difficult procedure, but it is not a region [the substernal space] that cardiologists are familiar working in,” famous Crozier, explaining the rationale behind a coverage of required implantation coaching.

Twenty-five opposed occasions occurred in 23 sufferers. Eighteen of those occasions required a system revision, together with 9 lead dislodgments and 5 infections. The seven opposed occasions that didn’t require a revision included three wound-related episodes and three hospitalizations for inappropriate shock. No sufferers died, nor have been there any cardiac accidents as results of the implant.

During common follow-up of 10.6 months, the implanted units delivered antitachycardia pacing to 10 sufferers, efficiently terminating 32 of 46 episodes (70%), a fee that Crozier referred to as “very good, and very comparable to transvenous devices.” The units additionally delivered 18 applicable shocks that efficiently transformed all 18 episodes.

A ten% Rate of Inappropriate Shocks

However, 29 sufferers (10% of the examine cohort) obtained inappropriate shocks in 81 episodes, with a complete of 118 inappropriate shocks delivered, together with 34 episodes (42%) triggered by oversensing of a P wave.

“We fully acknowledge that the inappropriate shock rate is higher than what’s seen with transvenous ICDs, but the rate is comparable to what was seen in the early trials with subcutaneous ICDs,” stated Crozier. “We have a number of strategies to reduce the inappropriate shock rate to what we’d expect with conventional devices,” akin to ensuring that P waves will not be detected by the machine on the time of implantation, utilizing new algorithms to mitigate P wave sensing, and different programming adjustments, he added.

Two sufferers had lead fractures that Crozier attributed to atypical lead places and which are seemingly avoidable sooner or later. He expressed optimism that the extravascular ICD will keep away from the excessive lead fracture fee over time that continues to be an issue for ICDs with transvenous leads.

The examine additionally adopted a subgroup of 36 sufferers who underwent a prespecified protocol of power defibrillation testing that was profitable in all 36.

Crozier conceded that the extravascular ICD can not at present ship power pacing, however he expressed optimism that this functionality might be out there sooner or later.

“This innovative [extravascular] ICD system would be particularly beneficial for patients with ventricular arrhythmias that can be reliably pace terminated and avoid a transvenous endocardial lead, but more information is required,” concluded Kusumoto.

The examine was sponsored by Medtronic, the corporate that’s creating the extravascular ICD. Crozier is a marketing consultant to and has obtained analysis funding from Medtronic. Kusumoto had no disclosures.

This article initially appeared on MDedge.com, a part of the Medscape Professional Network.



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