Atherectomy Trial of Calcified Lesion Surprises

WASHINGTON, DC — Atherectomy has no advantage over conventional balloon angioplasty for the treatment of severe calcified lesions, according to unexpected results from the largest trial of the procedure ever conducted.

Target vessel failure — the primary clinical endpoint of the ECLIPSE trial — was numerically more frequent at 12 months in patients treated with orbital atherectomy than in those treated with balloon angioplasty (11.5% vs 10.0%; P Transcatheter Cardiovascular Therapeutics 2024.

For the primary imaging endpoint of minimal stent area at the site of calcification, the median was also numerically higher and produced a statistical trend in favor of balloon angioplasty (7.44 mm³ vs 7.05 mm³; P = .08).

The ECLIPSE results, which Kirtane presented during a late-breaker session, were characterized by several experts as an example of why randomized controlled trials are so important. Kirtane and multiple discussants said the results will likely lead to a reconsideration of the options available for treating calcified lesions.

The intention-to-treat analysis of ECLIPSE, conducted at 39 sites in the United States, assessed 276 patients with 286 lesions randomized to orbital atherectomy and 279 patients with 292 lesions randomized to balloon angioplasty. The median age was about 70 years, and more than 70% of participants were men. The most frequently targeted artery was the left anterior descending artery (61%), followed by the right circumflex artery.

The high proportion of procedures performed with intravascular imaging is notable and potentially relevant to the results. Of the two third of procedures performed with imaging guidance, 40% were guided with optical coherence tomography, and about 25% were guided with intravascular ultrasound.

Rates and types of intravascular imaging were similar in the two groups. This is important because outcomes were better with imaging, according to Kirtane, and could explain the higher-than-expected success rate in the balloon group. One message from this study, he said, is that intravascular imaging should be employed routinely in the treatment of calcified lesions, no matter the intervention.

Rethinking Treatment After ECLIPSE

Ultimately, the ECLIPSE results show that “adequate stent expansion and low rates of adverse outcomes are achievable with conventional balloon angioplasty in a substantial proportion of severely calcified lesions if meticulous attention — including intravascular imaging — is paid to lesion preparation,” Kirtane said.

By a substantial proportion, ECLIPSE was not an all-comer trial. Even though 97% of the target lesions in both groups were classified as severely calcified by an independent core laboratory, participating investigators were permitted to exclude patients whose lesions they considered to be inappropriate for balloon angioplasty because of characteristics such as exceptional calcification and vessel tortuosity.

Moreover, 4.9% of patients enrolled in the balloon group and 2.0% enrolled in the atherectomy group were not treated with their assigned intervention. Some patients in each group crossed over to the opposite group, and about 25% of patients were ultimately treated with rotational atherectomy or intravascular lithotripsy.

Baseline characteristics of the two groups were generally comparable, as were angiographic characteristics, but neither the patients nor the operators were blinded to assignment. The lack of blinding is the reason that several experts evaluating this result questioned whether, on the basis of these results, atherectomy and balloon angioplasty can be considered equivalent.

“Patients with very severe calcified lesions were probably not considered for the trial,” cautioned invited discussant Mohamed Abdel-Wahab, MD, head of structural heart disease at Heart Center Leipzig in Leipzig, Germany.

Although the study suggests that balloon angioplasty can be used effectively for preparing most severely calcified lesions, Abdel-Wahab pointed out that ECLIPSE was not designed to identify the best approach for addressing calcified lesions; it only addressed how orbital atherectomy compares with balloon angioplasty. The relative roles of rotational atherectomy and intravascular lithotripsy were not considered.

He praised “the first ever randomized control trial of orbital atherectomy” for proving that interventional trials of calcified lesions are feasible, and he pointed out it invites similar comparisons among other treatment options.

A similar opinion was expressed by Roxana Mehran, MD, director of interventional cardiovascular research at the Icahn School of Medicine at Mount Sinai in New York City, and by Anna Sonia Petronio, MD, associate professor of medicine at Pisa University Hospital in Pisa, Italy.

According to these experts, atherectomy, rotational atherectomy, intravascular lithotripsy, and balloon angioplasty are reasonable options for treating calcified lesions, but there has been no level I evidence comparing these. Although ECLIPSE addressed the relative role of orbital atherectomy and balloon angioplasty, the unexpected results increase the need for more comparative studies of all of these options, overall and for different levels of calcification.

Incremental improvements in balloon technology over the past several years might explain the unexpected results of ECLIPSE, said Wayne B. Batchelor, MD, director of interventional cardiology research at Inova Fairfax Hospital in Fairfax, Virginia, but he said he agrees that ECLIPSE underscores the value of employing intravascular imaging to improve results, regardless of treatment.

Petronio said she agrees.

“I think we see in these data the need and the importance of intravascular imaging in guiding management of calcified lesions,” she said.