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SAN FRANCISCO -- The novel Nanostim leadless pacemaker appeared safer overall than conventional pacemakers in a comparison of updated pivotal trial data against real-world claims data.
The leadless pacemaker had a 68% lower likelihood of serious device-related adverse effects (adjusted hazard ratio 0.32, 95% CI 0.24-0.43), , of Mount Sinai Hospital in New York City, and colleagues found.
A matched-cohort analysis yielded a similar difference, with an adjusted hazard ratio of 0.29 (95% CI 0.21-0.39) favoring the Nanostim device, Reddy reported at the here.
Action Points
- Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
- The novel Nanostim leadless pacemaker appeared safer overall than conventional pacemakers in a comparison of updated pivotal trial data against real-world claims data.
- Note that the Nanostim device has followed closely behind the similarly leadless Micra device, which was approved last month, and has been approved in Europe but is still investigational in the U.S.
The Nanostim device has followed closely behind the similarly leadless Micra device, which was approved last month, but concern has centered on cardiac perforation risk. Nanostim, made by St. Jude Medical, has been approved in Europe but is still investigational in the U.S.
Initially, the device was screwed into the apex; the active fixation site has now been switched to the septum.
"The right ventricular apex in particular is thin. When you screw anything in there, it's actually going through the wall. You can guarantee it's going through the wall, and the question is how much bleeding," commented , of Johns Hopkins and a past president of the American Heart Association.
The perforation rate "will get better with more experience, we're still on a bit of a learning curve," he noted.
Reddy suggested that the perforation rate could be reduced to below 1% as experience grows, noting that the trial did not require prior experience with the device among operators. The pericardial tamponade rate was 1.5% in the trial, compared with 0.3% among conventional pacemakers.
The study included 718 patients from the prospective LEADLESS II trial, updated from the 526 previously included in published data from the trial. Complications, recorded as serious device-related adverse events by standard definitions, didn't change much with the additional data, with a total rate of 6.4% (6.5% total ).
The comparator was retrospective transvenous pacemaker data from the Truven MarketScan insurance claims database. It pooled claims from about 350 private sector payers covering about 20% of the U.S. population and had 10,492 single-chamber, noncardiac resynchronization pacing patients with at least 1 year of data for analysis from April 2009 through March 2014. The complications were determined from clinical events generating claims.
Matching transvenous to Nanostim patients in a 3:1 ratio based on patient characteristics and comorbidities showed 1-month rates of:
- Lead dislodgement 0.97% versus 1.62%
- Vascular complications 1.11% versus 0.46%
- Cardiac perforation or pericardial effusion 1.53% versus 0.32%
- Thoracic trauma 0.00% versus 3.90%
- Lead complications 0.00% versus 10.12%
- Infection 0.00% versus 2.18%
- Pocket complications 0.00% versus 1.35%
Midterm outcomes from 1 month to 1.5 years showed no complications in the leadless pacing group, compared with 0.23% lead dislodgement, 1.75% lead complications, 2.34% infections, and 0.93% pocket complications in the conventional pacing group.
Choosing between a leadless pacemaker and a conventional transvenous lead pacemaker for the "very subsegmented group of patients -- these are for patients with a clear indication for single chamber pacemaking only" centers on balancing risks, , of Piedmont Hospital in Atlanta, commented as moderator at the press conference for the late-breaking clinical trial session.
"Upfront you take a much higher risk" with leadless pacemakers, he said, "but over time that begins to accumulate [for transvenous pacemakers] ... So then what happens down the road is what do you want to do in terms of paying the piper?"
The advantage for Nanostim, he said, "in this selected population is that you have individuals who have minimal or essentially no lead risk, but we don't know about the quality of device at 5, 7 years et cetera."
He suggested that because lead complications and infections are such a big concern among patients, leadless pacemakers, irrespective of manufacturer, could become the dominant strategy.
Reddy cautioned that baseline variables and definitions of complications and their ascertainment differed between the two cohorts and that simply totalling the complications could be a little misleading, as their clinical impact differs.
He told attendees at the late-breaking trial session that a randomized trial comparing the two approaches should be done and would likely require fewer than 1,000 patients, given the early divergence of the safety curves.
Disclosures
Reddy disclosed relationships with St. Jude Medical.
Primary Source
Heart Rhythm Society meeting
Reddy VY, et al "A comparative study of acute and mid-term complications of leadless vs transvenous pacemakers" HRS 2016; Abstract LBCT02-04.