A 2025 meta-analysis of 9,538 patients found trastuzumab emtansine (T‑DM1) carries the lowest incidence of LVEF decline (0.94%), while trastuzumab deruxtecan (T‑DXd) and trastuzumab-based combinations show similar, modest rates (≈4–5%). Trial selection and monitoring practices limit generalizability; baseline cardiac assessment and individualized surveillance remain essential.