Now You See Them, Now You Don’t: Bioresorbable Devices Target Large-Bore Closures and PE Prevention

LAS VEGAS, NV—Several novel bioresorbable devices were presented here this week at VIVA 2018 in late-breaking trial sessions. One offered a unique way to close large femoral artery access sites quickly, while another showed ongoing safety and efficacy of an inferior vena cava (IVC) filter that does not require retrieval.

Micah M. Watts, MD (Hospital of the University of Pennsylvania, Philadelphia), presented first-in-human experience with the Large Bore Closer (Rex Medical) vascular sealing system, which provides rapid hemostasis, often without need for heparin. Watts showed a video demonstrating how the device resulted in instantaneous stoppage of bleeding in 74% of the 23 patients in the study.

The device consists of a delivery system with a vessel sealing patch and a self-aligning fully resorbable sealing mechanism. After the device has been deployed and the plug-like patch is in place, two retention spheres, which Watts described as being similar to BB gun bullets, are mechanically attached to the top with sutures. The patch and spheres are made from poly(lactic-co-glycolic acid), while the sutures consist of polydioxanone monofilament.

“In 60 days it should be fully resorbed and basically leave nothing behind,” Watts said, adding that the system is extremely simple to use.

In the study, all patients underwent procedures performed through 10- to 16-Fr introducer sheaths. At 60 days, the primary safety endpoint (freedom from 30-day major adverse events) was achieved in all patients. Mean time to hemostasis after deployment of the closure device for patients not receiving heparin (n = 13) was 1 minute and 2 seconds. Of those, seven patients achieved instantaneous hemostasis. For the other 10 patients who did receive heparin, mean time to hemostasis was 2 minutes and 12 seconds. Additionally, the mean activated clotting time at deployment of the closure device was 218 seconds.

The device currently has premarket approval for use with 7- to 8-Fr introducer sheaths.

Session co-moderator John Rundback, MD (Holy Name Medical Center, Teaneck, NJ), noted that there is “clearly a big need [for innovative closure] as we expand the interventional armamentarium to include larger devices.”

Bioconvertible IVC Filter Associated With Low Rates of PE at 2 Years

In the second presentation, Michael Dake, MD (University of Arizona Health Sciences, Tucson), presented a 2-year analysis of the multicenter SENTRY clinical trial, which is testing safety and efficacy of the BTG Sentry (BTG) fully bioconvertible IVC filter. Earlier results from the study were released at ISET 2018.

Dake noted that the subject of IVC filtration remains controversial and that next-generation devices may help alleviate the safety concerns that have swirled around retrievable IVC filters in recent years. Following reports of high rates of device-related complications from retrievable filters that were not removed, the Food and Drug Administration issued an advisory for physicians to retrieve them between 29 and 54 days after implantation. The result, Dake said, has been a decline in use of the filters since 2010.

“As we know, IVC filters used correctly save lives and reduce injury and cost related to [pulmonary embolism (PE)],” Dake said. “Survival benefit has been shown in appropriately selected patients. Existing retrieval technology, however, has not effectively met the needs of the medical system.”

Dake presented 2-year follow-up for 129 patients treated at 23 centers in the single-arm SENTRY trial. All required temporary protection due to high risk for PE. All had contraindications to anticoagulation for some or all of the protection period.

Overall, 94% of eligible patients underwent follow-up imaging at 24 months with CT venogram as part of what Dake called a “highly intensive imaging protocol.” There were no instances of the filter migrating, tilting, embolizing, fracturing, perforating, or any other device-related complication out to 24 months.

The filter automatically bioconverts after 60 days via hydrolysis that allows the filter arms to retract from the IVC wall. The rate of symptomatic new PE in patients with fully bioconverted filters was 2.4% through 2 years, with none of the events related to the device.

“It’s easy, accurate, tends not to jump, and it almost always is aligned along the longitudinal access of the cava,” Dake said. The rate of successful bioconversion of the filter was 96.5% at 2 years.

Asked by session moderator Krishna Rocha-Singh, MD (Prairie Heart Institute at St. John's Hospital, Springfield, IL), how anticoagulants were addressed, Dake said those regimens were left to the discretion of individual physicians, with no standard anticoagulation regimen mandated for patients with successful placement of a filter.

Another interesting question raised by Rocha-Singh is what happens if the filter traps a clot right before it dissolves. Dake noted that there were 16 patients who were asymptomatic and had clots seen partially within the filter. None were not intervened on, and none developed symptomatic PE.

“[T]here’s a pretty large patient population that I think could potentially benefit from this,” Dake concluded.