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.
Dr. Dean J. Kereiakes
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 Dr. 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,” Dr. 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.