Earlier this year, researchers debuted single-centre experiences indicating that intravascular lithotripsy (IVL) may be able to expand transcarotid artery revascularisation (TCAR) into patients with traditionally prohibitive calcific disease. With a multicentre case series now further suggesting IVL’s utility, but also revealing potential safety concerns versus conventional TCAR or carotid endarterectomy (CEA), principal investigator Misty Humphries (University of California Davis, Sacramento, USA) gives NeuroNews the lowdown on these findings.
Could you very briefly outline the motives behind this research?
TCAR has been shown to be highly effective and safe, but there are still anatomic exclusion criteria—specifically, severe calcification. There are also many patients who are just not a candidate for traditional CEA for various reasons. The use of IVL has the potential to open TCAR technology up to more patients.
How do these more recent, multicentric findings build on your publication from earlier in the year?
With our initial presentation, we discussed how we do the procedure. That presentation was our own institutional data. When we analysed our own experience, we had no complications, and the technology appeared safe. But, in this larger, multicentre cohort, we see a risk of transient ischaemic attack (TIA) post-procedure that was not present. Multicentre studies like this demonstrate what can happen when technology is expanded to more practitioners of various skill levels.
Why was freedom from stroke/TIA selected as the study’s primary safety endpoint?
Stroke and TIA are the two outcomes patients care about most. We saw this with the CREST trial data that were analysed. All of my research is patient-centred and, for me to use technology, I want to know that it is safe—not just for what providers care about, but for what patients care about as well.
What were the key safety and efficacy findings of the study?
IVL combined with TCAR seems to be highly effective, allowing full stent expansion. The safety of the combined treatment needs to be studied in a prospective trial. There are not a significant amount of known data on the risk of stroke and TIA in patients with severe calcium after carotid artery stenting (CAS) because these patients are typically excluded from trials. The best data we have were presented at the Society for Clinical Vascular Surgery (SCVS) annual symposium (25–29 March, Miami, USA) earlier this year. In a review of Vascular Quality Initiative (VQI) patients who underwent TCAR and CAS, patients with severe calcium had a higher risk of stroke/TIA than those who did not. This tells us that it is the disease process, and we need to learn more about this.
How significant is it that a technical success rate of 100% was achieved?
Technical success of 100% means we can do the procedure. The real question is how to do the procedure effectively and safely. I do not think we know that yet.
How concerning is the increased stroke/TIA rate versus conventional TCAR or CEA—would the benefits of IVL plus TCAR still outweigh these risks?
Studies that break out results based on the degree of calcium are lacking because these patients are excluded from TCAR trials. The VQI data presented at SCVS 2023 show that patients with higher degrees of calcium have increased stroke rates with TCAR and CAS. I truly believe that heavily calcified patients are better served with CEA, but there are some patients that cannot undergo CEA and, in those patients, IVL with TCAR is an answer. We are just exploring how to do this procedure in the best way for patients. We also need to do a prospective trial where we control for all factors, such as Plavix (clopidogrel) resistance, and procedural or postprocedural hypotension.
