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Leadless pacemaker safe, effective in early testing
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Early testing in 33 patients showed that a self-contained, single-chamber leadless cardiac pacemaker was safe and effective.
In the prospective nonrandomized LEADLESS study, the pacemaker (Nanostim, St. Jude Medical/Nanostim Inc.) was evaluated for freedom from complications, implant success rate, implant time, pacing/sensing thresholds and rate-responsive performance.
A leadless pacemaker could reduce or eliminate short-term complications related to transvenous implantation and long-term complications such as venous obstruction, insulation breaks, conductor fracture and infection, according to the study background.
Vivek Y. Reddy
“While a much larger study is required to prove this, one may expect the leadless pacemaker to be associated with less chance of infection and lead-related problems such as lead fracture,” Vivek Y. Reddy, MD, director of the cardiac arrhythmia service at Mount Sinai Hospital, said in a press release. “Overall, the self-contained pacemaker is a paradigm shift in cardiac pacing.”
Reddy and colleagues tested the pacemaker in 33 patients (mean age, 77 years; 100% white; 67% men) at three sites in Europe. The most common indication for pacing was permanent atrial fibrillation with atrioventricular block. The primary outcome was freedom from complications at 90 days.
The device was delivered to the right ventricle using a deflectable delivery catheter with an extendable sleeve to protect the fixation helix, according to the study background. After it was properly positioned, the sleeve was retracted, implanting the device into the endocardium and undocking it from the delivery catheter, the researchers wrote.
The implant success rate was 97% and the complication-free rate at 90 days was 94%. One patient developed right ventricular perforation and cardiac tamponade during the procedure and eventually died from a stroke, according to the study.
Seventy percent of patients did not require any repositioning of the pacemaker after implantation, and 15% required more than one pacemaker, Reddy and colleagues wrote.
Mean procedure duration was 28 minutes and mean time to hospital discharge was 31 hours.
Compared with the time of implantation, there was improvement at 12 weeks in mean R-wave amplitude (+2.3 mV; P<.0001), mean pacing thresholds (–0.31 V; P=.0011) and mean impedance (–143.8 ohm; P=.0002).
The burden of pacing was 37% at 2 weeks, 39% at 6 weeks and 42% at 12 weeks.
St. Jude Medical announced in October that the Nanostim leadless pacemaker received CE mark approval for use in Europe. In February, St. Jude Medical announced the launch of the LEADLESS II pivotal trial for the device. LEADLESS II is expected to enroll approximately 670 patients in the United States, Canada and Europe.
Disclosure: The study was funded by Nanostim Inc., which is now owned by St. Jude Medical. Two researchers are employees of Nanostim and three report financial ties with Nanostim.
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