Updated May 12, 2014, at 5:30 p.m. with confirmation from St. Jude Medical.
It was good news mixed with bad for St. Jude Medical’s (NYSE:STJ) Nanostim lead-free implantable pacemaker at last week’s Heart Rhythm 2014, the Heart Rhythm Society’s 35th Annual Scientific Sessions.
Nanostim continued to look promising at 1 year in a small feasibility study, but concerns about patient safety led the company to temporarily suspend enrollment in an overseas registry. Researchers reported 6 instances of perforation, including 2 patient deaths, out of more than 200 implants, according to an note from Leerink Swann analyst Danielle Antalffy.
St. Jude suspended the study in April in response to the patient deaths, according to a statement sent to MassDevice.com today. The company evaluated the reports and presented its findings to the trial’s steering committee, which unanimously agreed to resume enrollment.
St. Jude’s analysis determined that the adverse events were due in part to inappropriate patient selection and in part to operator inexperience, according to Antalffy’s note. The company determined that 5 of the 6 perforations "would not have occurred if the European registry aligned with the U.S. pivotal inclusion/exclusion criteria," she wrote.
The trial is slated to reopen enrollment, likely in the next week or so, the company said. St. Jude is updating the study protocol to match U.S. enrollment criteria, and the company is making efforts to ensure all investigators are updated and on board with the new guidelines.
The adverse events haven’t dampened physician enthusiasm about the Nanostim device, a lead-free pacemaker smaller than a AAA battery that sits entirely within the heart to help correct abnormal rhythms. St. Jude is leading the way with lead-free pacing, but arch-rival Medtronic (NYSE:MDT) has its own clinical trials in the works.
"Enthusiasm for lead-less pacing – both STJ and MDT are currently enrolling U.S. pivotal trials – was unanimous among all physicians with whom we spoke," Antalffy wrote. "One physician expects to use lead-less pacing in 100% of his single chamber patients, while others pegged the market at 10%-20% of patients receiving pacemakers – potentially positioning both STJ and MDT for meaningful market share gains upon approval."
St. Jude remains enthusiastic, as well.
"Overall, we’ve had positive clinical outcomes in both Europe and the U.S. and remain very excited about this technology," according a company statement.
The technology is a major departure from standard pacemakers, which rely on leads to transmit pulses from a generator to the heart. Leads have long been cardiac rhythm therapy’s "weakest link," having been the subject of several major recalls in recent years.
In addition to the 1st LEADLESS feasibility study, which is no longer enrolling patients, St. Jude is currently in the middle of a 667-patient investigational device exemption trial in the U.S. and a 1,000-patient European post-approval study.