BACKGROUND: Transcatheter electrosurgical leaflet splitting prevents coronary artery obstruction (CAO) following transcatheter aortic valve replacement (TAVR), particularly in valve-in-valve interventions. Morphologic and fluoroscopic differences between stented and stentless valves may affect outcomes, but comparative data are limited. OBJECTIVES: The aim of this study was to compare procedural characteristics and outcomes of BASILICA (bioprosthetic or native aortic scallop intentional laceration to prevent iatrogenic CAO) and TAVR in stented vs stentless surgical bioprosthetic valves. METHODS: A total of 131 patients undergoing BASILICA and valve-in-valve TAVR from the multicenter EURO-BASILICA registry were included. Patients were stratified by valve type (stented vs stentless), and outcomes were described according to Valve Academic Research Consortium 3 recommendations. RESULTS: Overall, 115 patients (87.8%) had stented valves and 16 (12.2%) had stentless valves. Risk for CAO was comparable, but stentless valves had longer leaflets (17.0 vs 14.0 mm; P < 0.001). Procedures in stentless valves required more contrast medium (174.0 vs 91.0 mL; P < 0.001) and longer fluoroscopy (61.7 vs 41.0 min; P = 0.023) and showed a trend toward longer procedure time. Technical success was similar, but stentless valves were associated with a significantly higher rate of target leaflet-related CAO (44.4% vs 7.1%; P < 0.001), which was mainly partial and non-flow-limiting (33.3% vs 3.9%; P < 0.001). In-hospital complications and 30-day outcomes were similar. No late CAO or myocardial infarction occurred during 1-year follow-up. CONCLUSIONS: BASILICA is technically feasible for both stented and stentless valves. However, stentless valves had a higher rate of partial CAO after BASILICA and TAVR and may therefore require additional or alternative coronary artery protection measures in selected patients.