BACKGROUND: BATMAN (balloon-assisted translocation of the mitral anterior leaflet) is an increasingly adopted technique to modify the anterior mitral leaflet (AML) and prevent left ventricular outflow tract (LVOT) obstruction during transcatheter mitral valve replacement (TMVR). OBJECTIVES: The aim of this study was to evaluate the feasibility, efficacy, and safety of the BATMAN technique during transseptal TMVR. METHODS: This was an international, multicenter cohort study of all consecutive patients at high risk for LVOT obstruction undergoing transseptal BATMAN TMVR for valve-in-valve (ViV), valve-in-ring (ViR) and valve-in-mitral annular calcification (ViMAC) at 22 structural heart disease centers in North America and Europe. The primary efficacy endpoint was the rate of successful TMVR free from LVOT obstruction and procedural death. The primary safety endpoint was the in-hospital composite of death, stroke, or major cardiac structural complications. RESULTS: A total of 83 patients were included: 24 undergoing ViV, 39 ViR, and 19 ViMAC procedures. Technical success was achieved in all but 1 case (98.8%) that was converted to tip-to-base LAMPOON (laceration of the anterior mitral leaflet to prevent outflow obstruction). Pre-emptive mechanical cardiocirculatory support was used in 28.9% of cases. The primary efficacy endpoint was met in 95.1% of cases (100% in ViR, 95.8% in ViV, and 84.2% of ViMAC; P = 0.03). The primary safety endpoint occurred in 7.3% of patients and was higher in the ViMAC group (0% in ViR, 8.3% in ViV, and 21.1% in ViMAC; P = 0.02). There was 1 major cardiac structural complication directly attributed to BATMAN in a ViMAC patient. CONCLUSIONS: BATMAN was associated with high technical success and effectiveness in preventing LVOT obstruction and appeared to be safe in ViR and ViV procedures. Adverse events were higher in ViMAC.