Carotid Stent Fractures Pose Very Little Threat to Patients, Study Finds

LAS VEGAS, NV—On the rare occasion that carotid stents fracture, they do not appear to increase a patient’s risk of adverse events, according to a prespecified analysis of the ACT I trial presented here today in a late-breaking trial session at VIVA 2016. 

Details on the outcomes of patients who experience carotid fractures are sparse and primarily limited to small case series or individual case reports, according to lead investigator Ido Weinberg, MD (Massachusetts General Hospital, Boston, MA). The ACT Idata, which come from a large comparison between carotid artery stenting (CAS) and endarterectomy, show no difference in clinical events between patients who did and did not have a fracture during five years of follow up.

In a press conference prior to the presentation, moderator Mark Burket, MD (University of Toledo Medical Center, Toledo, OH), said he had been curious about the stent fracture phenomenon for some time. “This is something that hasn’t been looked at in the past, and so personally I was quite interested in the study and also reassured at the same time that there really appears to be very little threat [when fractures occur],” he said.

No Difference in Death, Stroke, MI, or Restenosis

ACT I enrolled 1,453 patients with severe carotid stenosis at 62 US sites from 2005 to 2013. Patients were all younger than 80 years, had standard surgical risk, and were randomized 3:1 to treatment with the Xact stent and an Emboshield, Emboshield Pro, or Emboshield NAV6 protection device (all Abbott Vascular) or to endarterectomy.

As part of the protocol, patients were required to undergo annual duplex ultrasound. Yearly radiographic analysis for stent fracture was added later, after the first 771 patients had been enrolled. Among the 1,021 patients eligible for analysis, the overall rate of stent fractures at 5 years was 5.4%, with the majority of those being grade 1 single-tine fractures, Weinberg reported.

When 51 patients who had a fracture were compared with 970 who did not, those with a fracture were more likely to have had a previous endarterectomy (13.7% vs 5.3%; P = 0.02). Stent-fracture patients also were more likely to have calcifications on angiography. Duplex findings between the two groups, however, showed no differences. Additionally, restenosis rates at 2 years were low and equivalent in stent-fracture patients and those with no fracture (4.4% vs 5.3%; P = 1.00).

Overall, there were no differences based on stent fracture at 5 years for the primary outcome (a composite of death, stroke, and MI at 30 days, and ipsilateral stroke from 31 days to 1 year), which occurred in 4.1% of those with a fracture and 5.2% of those without (P = 0.68). There also was no difference between groups for clinically-driven TLR.

Although the study was not powered to look at causes of fractures, Weinberg said, more study is needed to evaluate their correlation with preexisting factors. He added that the ACT I study group will be looking at both patient and imaging characteristics that may be applicable.

Findings Bolster Trial Data on CAS Safety

Following the presentation, moderator Michael Dake, MD (Stanford University Medical Center, Stanford, CA), commented that one of the take-home messages is that “we may not have fracture-resistant stents, but we’re getting fracture-safe stents.”

Similarly, panelist Joshua A. Beckman, MD (Vanderbilt University Medical Center, Nashville, TN), called the presentation “incredibly important,” noting that “there is an ongoing fear of stent fracture and what it means.”

Demonstrating that fractures do not increase the risk of restenosis adds further support for the safety of CAS versus endarterectomy for carotid stenosis and is a “reassuring point” that supplements available data from the randomized trials, said panelist Christopher Metzger, MD (Wellmont CVA Heart Institute, Kingsport, TN).