Use of intravascular lithotripsy (IVL) for the treatment of in-stent restenosis (ISR), although off-label, may be safe and feasible, according to a study reviewing data from the ACC's CathPCI Registry published in JACC: Cardiovascular Interventions.

There were 18,893 patients who underwent PCI with the C² Coronary IVL system from March 2021 to March 2022 recorded in the registry, and Dean J. Kereiakes, MD, FACC, et al., found 3,686 of these patients were treated for ISR. Baseline characteristics, site-reported procedural outcomes and in-hospital mortality were included in the analysis. The authors also assessed observed vs. predicted in-hospital mortality by using the validated NCDR-derived bedside risk score model.

The site-reported mean diameter stenosis for IVL-treated lesions was 86.7±11.9%, while mean lesion length was 28.2±19.7 mm, type C lesion complexity was seen in 69.4% of cases and severe calcification noted in 45.3% of cases. According to the authors, "no additional information regarding the presence or morphology of calcium was recorded." Mean residual stenosis postprocedure was 7.1±14.2%, with 95.6% of cases exhibiting <50% residual stenosis.

Adverse events occurred in 5.3% of patients, including bleeding complications in 1.6% of patients and cardiac arrest in 1.2% of patients. Among patients who experienced cardiac arrest, 64% presented with STEMI or NSTEMI.

In-hospital mortality among the ISR patient group was 1.3%. This observed rate was lower than the 1.7% prediction based on the NCDR-derived bedside risk score (relative risk, 0.75; 95% CI, 0.55-0.99; p=0.04).

"Future studies are warranted to define the optimal use of IVL and adjunctive strategies in the ISR treatment algorithm as well as longer-term outcomes," write the authors. "Nonetheless, the present encouraging outcomes suggest that IVL may be a safe and feasible treatment for ISR."