The Leadless Observational Study
Research type
Research Study
Full title
Nanostim Study For a Leadless Cardiac Pacemaker System - The Leadless Observational Study
IRAS ID
141819
Contact name
Ashish Oza
Contact email
Sponsor organisation
St Jude Medical
Duration of Study in the UK
6 years, 0 months, 1 days
Research summary
Summary of Research
This study is to confirm the clinical performace and safety of the Nanostim leadless cardiac pacemaker.
A pacemaker is used to control the heart rate in patients who have a slow heart rate - it does this by stimulating the heart muscle with an electrical pulse to make it beat.
A normal pacemaker consists of a small metal can called the pacemaker that sits under the skin on the upper chest and one or more leads are used to connect the pacemaker to the heart muscle. The leads are enter the heart through veins. The nanostim leadless pacemaker is a small pacemaker that is placed directly inside the heart and connects to the heart without the need for a lead.Summary of Results
The Leadless Observational Study evaluated the Nanostim Leadless Pacemaker (LP), a CE-marked device. The Nanostim LP was shown to be safe and effective in a pre-market clinical investigation. However, due to the limited duration of the pre-market investigation, the limited number of subjects enrolled, and the controlled setting of the pre-market clinical investigation, important information about potential residual risks related to the LP were collected in a post market setting in larger number of patients implanted at a broad group of centers. The purpose of the Leadless Observational Study was to confirm clinical performance and safety of the Nanostim leadless cardiac pacemaker system, within its intended use and according to its instructions for use, in a post market setting.This was a prospective, non-randomized, single-arm, multicenter, post-market study. The first subject was enrolled on December 23, 2013 and the last follow-up visit was completed on January 21, 2022. The Post Market Clinical Follow-up (PMCF) requirement for CE mark was completed when data from 300 enrolled subjects followed for 6 months was collected in the study. As of the cut-off date of this report, 491 subjects were enrolled in the study. The study did not meet the enrollment goal of 1000 patients since enrollments were suspended and not continued due to reports of docking button detachments and battery malfunction with Nanostim LP devices. No patients have been enrolled in this study since the issuance of the battery malfunction medical advisory in October 2016.
Subjects at least 18 years old, and who were indicated for a VVI(R) pacemaker were enrolled in the study. Subjects who participated in the pre-CE mark LEADLESS study or were implanted with a Nanostim LP within 3 months of the study start at one of the selected sites involving physician trainers and study leaders were able to enroll in this study. The pre-CE mark LEADLESS study patients as well as the patients implanted before the study pause in April 2014 counted towards the total sample size, however they were not part of the sub-set of 300 patients needed to meet the PMCF requirements.
After successful implant of the LP, participants were followed at pre-discharge and post-implant at 90 days, 180 days, and every 6 months thereafter through 5 years for assessment of complications. Additional collected data include device performance up to 6 months post-implant, implant success rate, procedure times, and time to discharge.
The primary safety endpoint is complication-free rate (CFR) at 180 days in 300 PMCF subjects who have either completed a 6-month visit, withdrew or died before the 6-month visit, or crossed their 6-month visit window without completing a 6-month visit. Complications for the primary safety endpoint are defined as serious adverse device effects (SADEs). The primary safety endpoint was evaluated for the sub-set of 300 subjects for the PMCF requirement at the time of the PMCF report analysis completed in May 2017. The study met the primary safety endpoint. The supplementary endpoint for freedom from complications (serious adverse device effect) at 90 days and 5 years were evaluated for this final report based on all subjects with attempted implant. The complication free rate at 90 days was 94% (95% CI: 91.5% to 95.8%). The complication free rate remained constant for the first year and there was a sharp decrease with the complication free rate at 5 years reaching 55.9% (95% CI: 50.3% to 61.2%). Hypothesis testing was not completed at the 5-year time point since the required sample size of at least 463 subjects at the 5 year follow up was not met since Nanostim LP implants were discontinued. An additional post-hoc analysis was done to assess the impact of the medical advisories related to battery malfunction and detached docking button on the long-term complication free rate at 5 years. The complication free rate analysis was repeated, excluding all complications due to premature battery depletion, elective device replacement due to medical advisory, or detached docking button. The adjusted complication free rate at 5 years was 84% (95% CI: 79.3% to 87.7%).
Although the primary safety results of the Leadless Observational study were favorable, the supplementary endpoint for freedom from complications at 5 years could not be evaluated against the intended hypothesis testing analysis due to reported Nanostim device malfunctions that led to the decision to permanently suspend all enrollments in the Leadless Observational study. In addition, the Sponsor, Abbott, has permanently discontinued commercialization of the Nanostim LP device system.
REC name
East of England - Cambridge East Research Ethics Committee
REC reference
13/EE/0433
Date of REC Opinion
7 Feb 2014
REC opinion
Further Information Favourable Opinion