lithotripsy

can help TCAR expand into high-risk patients

Lithotripsy may hold the key to enabling more carotid artery disease patients who require calcification treatment to undergo stent placement via a transcarotid artery revascularisation (TCAR) procedure, as per single-centre experiences presented at the recent Society for Clinical Vascular Surgery (SCVS) annual symposium (25–29 March 2023, Miami, USA) by Kathryn DiLosa with principal investigator Misty Humphries (both University of California Davis, Sacramento, USA).

IN CASES OF CIRCUMFERENTIAL or eccentric calcification, TCAR is precluded and carotid endarterectomy (CEA) often becomes the preferred approach—however, in patients considered ‘high risk’ due to their anatomy, for example, “another alternative exists”, the speaker averred. Detailing the use of intravascular lithotripsy (IVL; Shockwave Medical) prior to a TCAR procedure, DiLosa noted that predilation angioplasty may be required to allow passage of a lithotripsy balloon, and the balloon “should be sized to fully oppose the vessel wall, but not extend past the intended coverage area”.

She further stated that lithotripsy technologies have been used in the treatment of kidney stones previously. The speaker also reported a 100% rate of technical success with this approach at her institution, across a total of seven patients, with comparable procedural

“Conversely, the incidence of perioperative myocardial infarction was lower in the alternative regimen group [than with DAPT],” the authors posit, highlighting rates of 0.4% and 0.7%, respectively. “At one year after the procedure, we observed an increased risk of mortality but not stroke in patients treated with an alternative medication regimen.”

Dakour-Aridi, Wang and colleagues ultimately convey that their propensity score-matched analysis found an increased risk of both in-hospital stroke and one-year mortality in TCAR recipients who were treated with an alternative approach to DAPT. And, although patients on triple therapy experienced the same rate of major adverse cardiovascular events (MACE) as DAPT, bleeding events were not available in the VQI, the authors also note.

“Further studies are needed to elucidate the drivers of DAPT failure in patients undergoing TCAR to improve outcomes for carotid stenting patients,” they conclude.

Trials

“THE TIME HAS DEFINITELY COME TO LOOK AT THE evidence, and redo these studies,” posited Alun Davies (Imperial College London, London, UK), putting forward his argument that the NASCET and ECST clinical trials “need to be reconducted” at this year’s Charing Cross (CX) International Symposium (25–27 April, London, UK).

and flow-reversal times to standard TCAR, and no observed complications within 30 days of the procedure.

“However, a larger cohort [of patients] is still needed to confirm safety,” DiLosa said.

Briefly touching on the available literature regarding pre-TCAR lithotripsy, she stated that case studies—but no significant case series—are available at this point, although she and her colleagues are currently compiling a multiinstitutional cohort including more than 50 patients.

“This is definitely for a specific patient population—those who cannot tolerate endarterectomy, but that would need the benefit of calcification [treatment],” DiLosa concluded.

Much of Davies’ argument centred around the fact that best medical therapy—the comparator arm against which carotid endarterectomy (CEA) was assessed, and found to produce clinical benefits in carotid artery stenosis patients, in both of these studies—is “significantly better than it was”.

After briefly outlining discrepancies between the North American NASCET and European ECST trials regarding how internal carotid artery stenosis was defined—with ECST having a higher threshold for severity—Davies also reminded the audience that NASCET observed a 3.3% stroke/death rate at one month in its medical therapy arm, compared to roughly 5–6% with CEA.

He then alluded to a 2003 paper by Ross Naylor (University of Leicester, Leicester, UK) et al that concluded, based on primary and secondary analyses of both trials, hat not all patients with symptomatic stenosis >70% will benefit from CEA.

Furthermore, he continued, recent research has shown that targeting and lowering a patient’s cholesterol, and initiating best medical therapy more quickly, can reduce adverse event rates by up to 80% early on. Applying this reduction to the rate of 3.3% seen in NASCET, he theorised that stroke/death incidence could now be as low as 0.7% with today’s best medical therapy.

This, coupled with uncertainties surrounding if—and in which cases—CEA is a cost-effective procedure, led Davies to reiterate that more randomised controlled trial data are now needed to re-evaluate the benefits of surgery versus medical therapy.

At the close of his presentation, the speaker highlighted the COMeT study—a proposed randomised trial comparing carotid intervention and best medical therapy that he and his colleagues are currently preparing to submit to the UK National Institute for Health Research (NIHR) for the second time, and for which they intend to enrol more than 2,500 patients.

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