TCT 2024: Abbott's coronary atherectomy study fails to outperform conventional balloon angioplasty

WASHINGTON, D.C.—A large-scale, randomized trial of the orbital atherectomy system Abbott picked up last year failed to show it could outperform conventional balloon angioplasty as a tool to prepare blockages within the heart’s coronary arteries ahead of the implantation of a stent.

The company’s Diamondback 360 system is designed to etch away at the inside of severely calcified lesions, where hardened plaques can make it difficult to fully inflate a balloon or optimally expand a stent. After a guidewire is passed through the blockage, the catheter’s rotating burr sands down and fractures calcium along the walls of the blood vessel.

The ECLIPSE trial, presented as a late-breaking study at the Cardiovascular Research Foundation’s Transcatheter Cardiovascular Therapeutics (TCT) conference in Washington, D.C., had enrolled about 2,000 patients over a period of six years, with about half receiving orbital atherectomy followed by balloon dilation, compared to standard balloon angioplasty alone.

The addition of orbital atherectomy and a longer procedure did not result in the placement of wider drug-eluting stents, with similar averages of minimal stent area at the coronary artery site that had the most calcium.

At the same time, orbital atherectomy patients saw slightly higher rates of the targeted blood vessel failing after one year, though the difference was not statistically significant.

Failures included a combined count of cardiac-related deaths, myocardial infarctions linked to the treated vessel or the need to reopen the artery due to another blockage. Those events were recorded among 11.5% of patients in the orbital atherectomy group versus 10% with balloon angioplasty.

Eight cardiac deaths occurred in the orbital atherectomy arm, with zero in the control group; an analysis of those patients found four of the deaths were not linked with the treatment, while two were classified as related to the device and two as possibly related.

The study—conducted over the years spanning 2017 to 2023—also showed, in an hypothesis-generating analysis, that the growing use of intravascular imaging was associated with better outcomes on both sides of the trial.

Researchers said one of the main takeaways from the study was that adequate stent expansion can be achieved with conventional balloon angioplasty as long as meticulous attention is paid to correctly preparing the vessel before a stent and confirming it with imaging.

“I was surprised by the results, because we did, in clinical practice, know that there are a lot of patients with calcified lesions who are inappropriately treated,” said study presenter Ajay Kirtane, M.D., director of the interventional cardiovascular care program at Columbia University Irving Medical Center.

“We see people coming back with under-expanded stents, and we know that's due to inadequate lesion preparation,” Kirtane said at a TCT press conference. “So lesion preparation is something that all of us emphasize, but yet in clinical practice, it doesn't get done very well.”

“When I looked at the imaging results, though, I was less surprised—and the reason for that is that over the past 10 years, and while this study has been enrolling, we and others have taught and have evolved to the point where we really feel that the angiogram is insufficient,” he continued.

“You really need to assess what's going on with more imaging. With the balloon-based strategy, you dilate with the balloon, but then you have to see and make sure the balloon has had the desired effect. And when we do that in clinical practice, we certainly find that balloons work really well in a lot of cases—and these advanced [atherectomy] therapies should probably be reserved for cases that are either refractive to balloons or truly uncrossable at baseline.”

According to Abbott, the Diamondback 360 system—which it acquired in 2023 through its $890 million purchase of the devicemaker Cardiovascular Systems—has been used to treat more than 100,000 patients. And the company estimates that between 30% and 40% of patients who undergo percutaneous coronary interventions have moderate to severe levels of calcium in their arteries.

“I would have thought that it would have been a positive trial, too,” commented Kenneth Rosenfield, M.D., section head for vascular medicine and intervention at Massachusetts General Hospital.

“One thing I wonder is whether the population wasn't sub-segmented enough,” Rosenfield said at the press conference. “With the most challenging calcific lesions, if they had separated out those patients, would that have made a difference?”

“Because I think there are some patients that we just can't—even with the best of balloons—you just can't treat them and you really do need atherectomy,” he said. “I just hope this does not kill orbital atherectomy or rotational atherectomy, because there's definitely a role for it in some cases.”

The study’s results also raised questions for other methods for pre-cracking calcium, such as intravascular lithotripsy being developed by Shockwave Medical, which was acquired earlier this year by Johnson & Johnson for $13.1 billion. The researchers said that no lesion preparation strategy for severely calcified coronary arteries has been shown to improve clinical outcomes in a strong randomized trial.

“The idea that this could happen with any therapy, including Shockwave’s, is an open one, and they need to be tested,” Kirtane said, adding that future head-to-head studies of specific balloons and preparation strategies are in the works. “Frankly, a lot of these devices have come to bear through single-arm studies, and we don't know which of them is any better. And to be honest, the conventional balloon looks pretty good.”