Novel Implant Excels in BEST
First-in-man data found promising closure rate.
A first-in-man analysis of the BioSTAR, a bioabsorbable septal repair implant for the closure of atrial septal defects and patent foramen ovale, easily met all its endpoints of feasibility, safety and efficacy.
Treatment with this novel implant resulted in a high rate of early and complete closure, leading to an optimistic reception for the implant. “We believe this is the first use of a bioabsorbable material to treat structural heart disease in humans,” said Michael J. Mullen, MD, of the Royal Brompton Hospital in London, during a presentation of BEST trial data on Tuesday.
“All the devices were satisfactorily deployed, with excellent conformability and low profile.” There were no major complications during the procedures, which each took about 41 minutes to complete. The closure rate at 30 days, as assessed by contrast transthoracic echocardiography, was 92% (48 of 52 patients). At six months, the closure rate improved to 96% (54 of 56).
Treatment with the BioSTAR (NMT Medical) resulted in no major safety issues, Mullen said. Transient atrial arrhythmia was noted in five patients (8.6%) after implantation, and right atrial echogenic mass and urticuria were observed in one patient each (1.8%). All of these issues were eventually resolved.
A novel treatment
“The BioSTAR is the first in a new generation of devices that are bioabsorbable and specifically designed for closure of ASD and PFOs,” Mullen said.
“The device is a double-umbrella configuration (Figure 1) that uses a porcine acellular type I collagen matrix. The collagen is very carefully treated and purified, and subsequently cross-linked with carbodimide. In addition, the device can to be coated with a variety of drugs or cells. Our device was coated with heparin.”
Mullen said that in animal data, which now extends out for approximately two years, the matrix gradually enters a process of remodeling whereby it is eventually replaced with the host tissue (Figure 2) in a manner similar to the natural healing process.
Potential impact
Horst Sievert, MD, of the Cardiovascular Center Frankfurt in Germany, noted the potential impact of this treatment. “This is the first bioabsorbable device for catheter closure of intracardiac defects, but why is that important?” Sievert said.
“It’s important because these days patients with ASD/PFO are young and have a life expectancy of 30 to 80 years. They are not like most of our other elderly patients, who may be proud of having a ‘full metal jacket’ and bilateral hip replacement.
“Instead, these young patients would rather replace devices with their own tissues, and that is the major breakthrough of this technology.”
Sievert also pointed out some limitations of the research. “The closure rate was assessed by transthoracic echocardiography,” he said. “As most of us know, TEE or transcranial Doppler are standard in clinical trials and daily practice today.
“The sensitivity of TEE is, simply put, rather low. The residual shunt rate, therefore, may be higher for this trial.”
Sievert also noted that because this was a first-in-man trial, it was not designed or powered to detect significant safety issues. He said that future trials should investigate the possibility of device arm fractures, thrombosis formation on the device and device-induced fibrillation.
The mean age of participants in BEST was 46 years, and 60% were women. The majority of defects were PFOs (93%), and the mean defect diameter was 8.4 mm.
Initial data from the BEST trial will be published this year in Circulation. The Food and Drug Administration has reviewed the data and approved BioSTAR for use in the upcoming MIST II trial. A CE Mark for the device is expected by the end of 2006, Mullen said.