TCT Intravascular Lithotripsy Hailed as 'Game Changer' for Coronary Calcification

Bruce Jancin

October 19, 2020

Intravascular lithotripsy proved highly effective, safe, and user friendly as an adjunct to stenting for severely calcified coronary lesions at 30 days of follow-up in the pivotal Disrupt CAD III study aimed at gaining U.S. regulatory approval.

The technology is basically the same as in extracorporeal lithotripsy, used for the treatment of kidney stones for more than 30 years: namely, transmission of pulsed acoustic pressure waves in order to fracture calcium. For interventional cardiology purposes, however, the transmitter is located within a balloon angioplasty catheter, Dean J. Kereiakes, MD, explained in presenting the study results at the Transcatheter Cardiovascular Research Therapeutics virtual annual meeting.

In Disrupt CAD III, intravascular lithotripsy far exceeded the procedural success and 30-day freedom from major adverse cardiovascular event (MACE) performance targets set in conjunction with the Food and Drug Administration. In so doing, the intravascular lithotripsy device developed by Shockwave Medical successfully addressed one of the banes of contemporary interventional cardiology: heavily calcified coronary lesions.

Currently available technologies targeting such lesions, including noncompliant high-pressure balloons, intravascular lasers, cutting balloons, and orbital and rotational atherectomy, often yield suboptimal results, noted Kereiakes, medical director of the Christ Hospital Heart and Cardiovascular Center in Cincinnati.

Severe vascular calcifications are becoming more common, due in part to an aging population and the growing prevalence of hypertension, diabetes, and renal insufficiency. Severely calcified coronary lesions complicate percutaneous coronary intervention. They're associated with increased risks of dissection, perforation, and periprocedural MI. Moreover, heavily calcified lesions impede stent delivery and expansion – and stent underexpansion is the leading predictor of restenosis and stent thrombosis, he observed at the meeting, sponsored by the Cardiovascular Research Foundation. Disrupt CAD III was a prospective single-arm study of 384 patients at 47 sites in the United States and several European countries. All participants had de novo coronary calcifications graded as severe by core laboratory assessment, with a mean calcified length of 47.9 mm by quantitative coronary angiography and a mean calcium angle and thickness of 292.5 degrees and 0.96 mm by optical coherence tomography.

"It's staggering, the level of calcification these patients had. It's jaw dropping," Kereiakes observed.

Intravascular lithotripsy was used to prepare these severely calcified lesions for stenting. The intervention entailed transmission of acoustic waves circumferentially and transmurally at 1 pulse per second through tissue at an effective pressure of about 50 atm. Patients received an average of 69 pulses.

This was not a randomized trial; there was no sham-treated control arm. Instead, the comparator group selected under regulatory guidance was comprised of patients who had received orbital atherectomy for severe coronary calcifications in the earlier, similarly designed ORBIT II trial, which led to FDA marketing approval of that technology.

Key Outcomes

The procedural success rate, defined as successful stent delivery with less than a 50% residual stenosis and no in-hospital MACE, was 92.4% in Disrupt CAD III, compared to 83.4% for orbital atherectomy in ORBIT II. The primary safety endpoint of freedom from cardiac death, MI, or target vessel revascularization at 30 days was achieved in 92.2% of patients in the intravascular lithotripsy trial, versus 84.4% in ORBIT II.

The 30-day MACE rate of 7.8% in Disrupt CAD III was primarily driven by periprocedural MIs, which occurred in 6.8% of participants. Only one-third of the MIs were clinically relevant by the Society for Coronary Angiography and Intervention definition. There were two cardiac deaths and three cases of stent thrombosis, all of which were associated with known predictors of the complication. There was 1 case each of dissection, abrupt closure, and perforation, but no instances of slow flow or no reflow at the procedure's end. Transient lithotripsy-induced left ventricular capture occurred in 41% of patients, but they were benign events with no lasting consequences.

The device was able to cross and deliver acoustic pressure wave therapy to 98.2% of lesions. The mean diameter stenosis preprocedure was 65.1%, dropping to 37.2% post lithotripsy, with a final in-stent residual stenosis diameter of 11.9%, with a 1.7-mm acute gain. The average stent expansion at the site of maximum calcification was 102%, with a minimum stent area of 6.5 mm2.

Optical coherence imaging revealed that 67% of treated lesions had circumferential and transmural fractures of both deep and superficial calcium post lithotripsy. Yet outcomes were the same regardless of whether fractures were evident on imaging.

At 30-day follow-up, 72.9% of patients had no angina, up from just 12.6% of participants pre-PCI. Follow-up will continue for 2 years.

Outcomes were similar for the first case done at each participating center and all cases thereafter.

"The ease of use was remarkable," Kereiakes recalled. "The learning curve is virtually nonexistent."

The Reaction

At a press conference where Kereiakes presented the Disrupt CAD III results, discussant Allen Jeremias, MD, said he found the results compelling.

"The success rate is high, I think it's relatively easy to use, as demonstrated, and I think the results are spectacular," said Jeremias, director of interventional cardiology research and associate director of the cardiac catheterization laboratory at St. Francis Hospital in Roslyn, N.Y.

Cardiologists "really don't do a good job most of the time" with severely calcified coronary lesions, added Jeremias, who wasn't involved in the trial.

"A lot of times these patients have inadequate stent outcomes when we do intravascular imaging. So to do something to try to basically crack the calcium and expand the stent is, I think, critically important in these patients, and this is an amazing technology that accomplishes that," the cardiologist said.

Juan F. Granada, MD, of Columbia University, New York, who moderated the press conference, said, "Some of the debulking techniques used for calcified stenoses actually require a lot of training, knowledge, experience, and hospital infrastructure.

I really think having a technology that is easy to use and familiar to all interventional cardiologists, such as a balloon, could potentially be a disruptive change in our field."

"It's an absolute game changer," agreed Jeremias.

Kereiakes reported serving as a consultant to a handful of medical device companies, including Shockwave Medical, which sponsored Disrupt CAD III.

SOURCE: Kereiakes DJ. TCT 2020. Late Breaking Clinical Science session 2.

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