Lithotripsy Is a Blast for Tough Coronary Calcium in the Disrupt-CAD 2 Trial

September 26, 2019

SAN FRANCISCO — The interventional answer to heavily calcified coronary lesions could reside in a balloon catheter that blasts calcifications with bursts of acoustic energy, suggests an early-stage study of 120 patients.

A series of such energy pulses can send fractures throughout calcified coronary plaques, extensive or more focal, that ease lesion compliance to facilitate subsequent deployment of a drug-eluting stent (DES), researchers say about the intravascular lithotripsy (IVL) technique.

"I think that based on the available safety and utility data, IVL could be the first-line therapy for severe calcification. It's safe, it's highly effective, and its mechanism of action is clear," Ziad A. Ali, MD, DPhil, New York-Presbyterian Hospital, New York City, told | Medscape Cardiology.

Ali presented the results of a substudy from the Disrupt CAD 2 trial, based on optical coherence tomography (OCT) intravascular imaging with IVL, here at Transcatheter Cardiovascular Therapeutics Conference 2019. The substudy confirmed that IVL works by "circumferential calcium fracture."

He is also lead author on the September 25 publication of the full study, a single-group European postmarket evaluation of the Coronary IVL System (Shockwave Medical) that will be reported later in the meeting, in Circulation: Cardiovascular Interventions. The device in the coronaries remains investigational in the United States.

Ali said that in the current study and its 60-patient predecessor, Disrupt CAD 1, IVL wasn't hobbled by some of the limitations affecting other intravascular technologies currently used to prepare heavily calcified coronary lesions for subsequent stenting.

Those devices include rotational atherectomy (such as with Boston Scientific's Rotablator) and orbital atherectomy catheters — which as they advance can slide past heavily calcified segments of vessel wall — and laser catheters, whose energy can be hard to control, he observed.

All three can lead to coronary perforation and the poststenting "no reflow" phenomenon, and energy delivery in IVL is "more predictable" than in laser revascularization, Ali said.

The lithotripsy procedure appears to have least two big advantages over those alternative technologies, he proposed.

"It has an extremely low complication rate. In the 180 patients so far in the trials, there have been no perforations, which is very surprising given that this is a high-energy device." There have been no instances of "no-reflow" or "slow flow," he said, "and no dissection that couldn't be treated by a stent. So its safety profile is as good as, if not better than, conventional balloon angioplasty and stenting."

The other likely advantage, he said, is that IVL "requires absolutely no training. You don't have to be an expert operator to slide in the balloon and then press the button" that triggers the energy pulses. "That's a big deal, because there is an apprehension worldwide about using atherectomy, in terms of its risks."

A lot of operators "have a high threshold for using Rotablator because of fear of some of the complications that have happened in the past, like perforations, acute closure, or low-flow," agreed Michael J. Cowley, MD, Virginia Commonwealth University, Richmond.

"Their incidence is low with the right case selection and good technique," he told | Medscape Cardiology. But operators who don't have much Rotablator experience "are often reluctant to use it."

So, said Cowley, who isn't associated with the IVL studies, "the appeal of lithotripsy is that it's consistent, it works well, and it doesn't have some of the baggage that Rotablator has for low-volume operators."

But the caution, he added, is that the IVL experience so far has been limited, observational, and probably in "protocol-selected" cases. "What we see here is a proof of concept, that the technique is safe and works."

Disrupt-CAD 2 enrolled 120 patients with severely calcified coronary lesions, 62% in the left anterior descending artery and 25% in the right coronary artery, who underwent IVL in 2018 and 2019.

The reference vessel diameter for treated lesions averaged 3.04 mm, and treated-lesion length averaged 19.5 mm. The mean minimum lumen diameter was 1.21 mm, and the associated stenosis severity was 60% of luminal diameter.

The IVL catheter was positioned at and successfully used on all target lesions, with the help of predilatation using small balloons in about 42% of cases. No atherectomy of any kind was used during any of the procedures.

Seven patients, 5.8%, reached the study's primary end point of in-hospital major adverse cardiac events, which included cardiac death, myocardial infarction (MI), or target-vessel revascularization. All of the cases consisted of non-Q-wave MIs, Ali said.

Ali sees IVF as having the edge over atherectomy catheters for most cases with heavily calcified lesions. "But I don't think that atherectomy is going away, nor should it. There will be a subgroup of patients where the IVL will simply not be able to cross the lesion, in which case atherectomy devices will be used as a partnering tool."

Some lesions will still require debulking with rotational or orbital atherectomy, Cowley agreed. But IVL, he said, "I think will be an advance for everyday use. If you can get it across the lesion, it seems to modify it sufficiently so that you can get a very good result" with a stent.

"And because of its ease of use, there's probably better safety," Cowley said. "It's still on the horizon, but I think it's very promising."

Disrupt CAD 2 was sponsored by Shockwave Medical. Ali reports personal fees and equity in Shockwave Medical, Inc; grants from Cardiovascular Systems, Inc, and Abbott Vascular; and personal fees from Boston Scientific, AstraZeneca, ACIST Medical, Opsens Medical, and Cardinal Health, "outside the submitted work." Cowley had no disclosures.

Circ Cardiovasc Interv. Published online September 25, 2019. Full text

Transcatheter Cardiovascular Therapeutics (TCT) Conference 2019: Abstract TCT 27. Presented September 25, 2019.

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