IntravaScular Lithotripsy for the Management of UndILatable Coronary StEnt: The SMILE Registry.

Background: Intravascular lithotripsy (IVL) showed to be effective in dilating heavily calcified de novo coronary lesions but little is known about its performance in under-expanded stents management. Aim of this study was to assess the feasibility, effectiveness and safety of IVL for the treatment of stent underexpansion refractory to balloon dilatation.

Methods: A multicentre, retrospective cohort analysis was performed in patients undergoing IVL to treat under-expanded stents following non-compliant balloon expansion failure. Primary endpoint was successful IVL dilatation defined as IVL balloon delivery and application at the target site followed by an increase of at least 1 mm in minimal stent cross-sectional area (MSA) on intracoronary imaging or an increase of at least 20% in minimal stent diameter (MSD) by quantitative coronary analysis (QCA).

Results: Thirty-nine under-expanded stents (34 patients) were included. Two cases (5.1%) of multiple stent layers and one (2.5%) acutely under-expanded stent were treated. The median IVL balloon diameter was 3.1 mm (IQR: 2.5-3.5 mm) while the number of pulses emitted was 56.7 (IQR: 30-80). IVL was successful in 34 cases (87.1%), with significant improvement in MSD (post: 3.23 mm [IQR: 3-3.5 mm] vs. pre: 0.81 mm [IQR: 0.35-1.2], p < 0.00001) and MSA (post: 7.61mm [IQR: 6.43-7.79mm] vs. pre: 3.35 [IQR: 2.8-4 mm], p < 0.00001). Non-fatal peri-procedural ST-elevation myocardial infarction occurred in one case (2.5%) due to IVL balloon rupture. No cardiac death, target lesion revascularization and stent thrombosis occurred in-hospital and at 30-day follow-up.

Conclusions: Bailout IVL was feasible, efficacious and safe to improve refractory stent under-expansion.