Functional Assessment of Intravascular Lithotripsy for Stent Underexpansion.

Stent underexpansion from severe calcification leads to adverse outcomes. While intravascular lithotripsy (IVL) is effective pre-stenting, its role in treating stent underexpansion remains unclear. We conducted a multicenter, retrospective study of patients undergoing percutaneous coronary intervention (PCI) with IVL from January 2019 to 2025. Patients were categorized into two groups based on IVL use: the upfront group (IVL before stent placement) and the intrastent group (IVL for treating stent underexpansion). The outcomes included a quantitative flow ratio-based trans-stent gradient (QFR-TSG) > 0 post-PCI, target vessel failure, and major adverse cardiovascular events (MACE). Statistical analyses employed inverse probability of treatment weighting with logistic and Cox regression models and Kaplan-Meier survival curves. A total of 166 consecutive patients were included, with 79 (47.6%) in the intrastent IVL group and 87 (52.4%) in the upfront IVL group. Compared to the upfront IVL group, patients treated with intrastent IVL had a higher prevalence of diabetes mellitus (49.4% vs. 19.5%, p < 0.001). QFR-TSG > 0 was significantly more frequent in the intrastent IVL group (77.2% vs. 60.9%, p = 0.036). After IPTW adjustment, intrastent IVL was not significantly associated with increased MACE risk (OR 1.11; 95% CI 0.55-2.61; p = 0.240). Kaplan-Meier analysis similarly showed no difference in MACE-free survival between groups over a mean follow-up of 3.7 years (log-rank p = 0.299). Intrastent IVL yields inferior functional results versus upfront IVL but appears safe and may serve as a useful rescue option for stent underexpansion.