Lithoplasty Catheter Shocks, Fractures CAC, May Facilitate Tough PCI Cases DISRUPT-CAD

Neil Osterweil

November 03, 2016

WASHINGTON, DC — A catheter-based mash-up of balloon angioplasty and lithotripsy with the hybrid name "lithoplasty" was successful at delivering stents safely and with a low rate of complications in a small study of patients with heavily calcified coronary lesions.

The investigational percutaneous lithoplasty device consists of a balloon catheter that is also capable of delivering dispersive, nonfocused acoustic pulse waves to fracture calcifications prior to stent implantation. The lithotripsy pulses disrupt superficial and deep vascular calcium but minimize injury to soft tissue, according to its company. An angioplasty balloon on the same catheter is then inflated to restore blood flow at low pressures.

As reported by heartwire from Medscape, the Lithoplasty System (Shockwave Medical) recently received FDA approval for use in peripheral artery disease in patients with calcified vessels but has not been cleared for use in coronary circulation to date.

Among 60 patients with moderate to severely calcified de novo coronary lesions enrolled in the DISRUPT-CAD trial, operators achieved clinical success, the primary performance end point, in 57 of 60 patients (95%). Clinical success was defined as residual stenosis of less than 50% post-PCI with no evidence of an in-hospital major adverse cardiovascular event (MACE), defined as a composite of cardiac death, MI, or target-vessel revascularization.

Device success (successful delivery and lithoplasty treatment at the target lesion) was achieved in 59 patients (98.3%), and in all 60 patients the device facilitated stent delivery, reported investigators, led by Dr Todd J Brinton (Stanford University, CA and founder of Shockwave Medical).

A Better Alternative?

The device was developed to tackle the challenges posed by the use of specialty scoring and cutting balloons, which have significant difficulties with crossability, and rotational atherectomy devices that are associated with significant complications and involve setup, Brinton said here at TCT 2016.

"As a result, we came up with this idea of lithoplasty, the combination of a balloon and lithotripsy. The difference is we're using nondispersive, nonfocused lithotripsy," he said.

In DISRUPT-CAD, patients with stable or unstable angina or silent ischemia were screened, and those with moderately to severely calcified de novo coronary lesions with a reference vessel diameter from 2.5 to 4.0 mm, with stenosis of >50% and lesion lengths of <32 mm were enrolled.

The mean total procedural time was 92.9 minutes, including 32.3 minutes of fluoroscopy and 6.4 minutes of lithoplasty time.

Coinvestigator Dr Ziad Ali (New York-Presbyterian Hospital/Columbia University Medical Center, New York City) said in an interview with heartwire that the device requires two rounds of balloon inflation, withdrawal, and reinsertion to achieve optimum calcium fracturing and stent placement.

At 30 days of follow-up, there was a significant decrease in mean diameter stenosis, from 68% before the procedure to 13% after. The minimum lumen diameter increased from 0.9 mm pre-PCI to 2.6 mm post-PCI.

There were no cases of radial dissections, perforations, abrupt closures, slow flow, or no reflow.

Freedom from 30-day MACE, the primary safety end point, was seen in 95% of patients. All of the remaining 5% (three patients) with a MACE event had a non-Q-wave MI deemed by independent adjudicators as not likely to be related to the study device, Brinton said.

OCT Confirmation

A substudy of optical coherence tomography (OCT) imaging of vessels in 31 of the 60 patients confirmed circumferential calcium fracture and demonstrated high luminal acute gain in patients from the lowest to the highest tertiles of calcium burden.

Among all patients who underwent OCT, mean minimum lumen area increased from 2.2 mm2 pre-PCI to 6.0 mm2 post-PCI. The mean acute gain was 3.7 mm2.

The device "makes one of the most difficult parts of interventional cardiology easier, and that is management of severely calcified lesions," Ali told heartwire .

"There are some other applications that also make this exciting for use, in situations like an underexpanded stent or where the stent has already been placed and where an atherectomy would be a high-risk procedure that is contraindicated," he said.

"Calcification still remains a challenge in interventional cardiology, and the therapies we have are hard to deal with and they're all associated with complications, so if there's a safer, more effective way to manage calcium, I think it would be welcomed," said Dr Steven P Marso (University of Texas Southwestern Medical Center, Dallas) in an interview with heartwire .

"Lithotripsy is an old device with a new application. The question that I have is what's the effect of lithotripsy energy on normal-vessel wall architecture," said Marso, who comoderated the session where the data were presented.

The study was supported by Shockwave Medical. Brinton is a cofounder of the company. Ali has an equity stake in the company. Marso reported no relevant financial relationships.

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