First Published Data on Leadless Pacemaker Supports Efficacy, Safety

March 24, 2014

DALLAS, TX — The first published trial experience of a self-contained, entirely leadless pacemaker, designed to be permanent after endovascular implantation within the right ventricle, shows the device can safely provide single-chamber ventricular pacing[1]. The LCP (leadless cardiac pacemaker) (Nanostim/St Jude Medical)—its 6-m diameter, 42-mm long dimensions often compared to those of an AAA battery—has been approved for sale in Europe but remains investigational in North America.

The novel device potentially does away with the need for leads of any type and for a subcutaneous pocket, often a source of infection or complicated by erosion or hematoma. Transvenous leads can break or become dislodged and, less commonly, cause pneumothorax or tamponade, observe Dr Vivek Y Reddy (Mount Sinai School of Medicine, New York, NY) and colleagues in their report published online today in Circulation .

Moreover, they write, "The LCP eliminates the possibility of intrasystem connector issues, such as loose set screws and air in the header, because the endocardial pacing electrode and pulse generator are a single unit."

The device was implanted transfemorally into the right ventricles of 33 patients, mean age 77, with varying indications for pacing but most often for permanent atrial fibrillation for atrioventricular block. Implantation was successful in all but one patient (97%), who "developed right ventricular perforation and cardiac tamponade during the implant procedure and eventually died as the result of a stroke."

Of the remaining 32 patients, 23 did not require repositioning of the device after its initial deployment, the group writes. The mean procedure time was 28 minutes and the time to hospital discharge averaged 31 hours.

One further patient was readmitted for syncope during the 90-day follow-up, but the LCP was found to be properly positioned and working. The patient was later found to have monomorphic VT, prompting removal of the LCP; he was later implanted with a defibrillator.

Overall, therefore, 32 patients (94%) were free of serious complications during the study, according to Reddy et al.

The LCP can be set to the VVIR mode at most and so isn't for patients requiring dual-chamber sensing and pacing, the group noted. However, "it is anticipated that leadless dual-chamber (multisite) pacing will become possible with further development. Only a randomized trial with a control group could prove the hypothesis that there would be more complications with traditional pacemakers."

The study was funded by Nanostim, which was acquired by St Jude Medical last year. Reddy discloses grant support and receiving stock options from Nanostim. Disclosures for the coauthors are listed in the paper.

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