BACKGROUND: The evolving landscape of mitral valve transcatheter edge-to-edge repair (M-TEER) for mitral regurgitation (MR) has seen continuous advancements, driving improvements in therapeutic efficacy. Particularly in primary MR (PMR), contemporary device iterations of M-TEER offer technical advantages for improved management of complex anatomies. However, data on temporal trends in M-TEER for PMR are limited. AIMS: The primary objective of our study was to analyse temporal trends in the safety, efficacy, and stability of M-TEER treatment. METHODS: The PRIME-MR registry, a retrospective multicentre study, enrolled consecutive patients undergoing M-TEER for PMR at 27 centres in Europe and North America. M-TEER procedures were categorised into four time periods (2009-2013, 2014-2016, 2017-2019, and 2020-2023), to align with major device updates. RESULTS: The analysis included 3,082 consecutive patients (median age 82 years [interquartile range 76.0-85.0], 45.1% female). Patients treated were highly symptomatic (New York Heart Association [NYHA] Class ≥III in 80.4%). Patient characteristics showed a decline in symptomatic severity (NYHA Class ≥III 85.9% in 2009-2013 vs 71.8% in 2020-2023), accompanied by lower mean Society of Thoracic Surgeons scores (5.6% [2009-2013] vs 4.6% [2020-2023]; p for trend<0.0001), and less severe MR. Over time, complication rates decreased (procedures with complications: 42.4% [2009-2013] vs 23.1% [2020-2023]; p for trend<0.0001), whereas technical efficacy increased (residual MR ≤1+: 54.0% [2009-2013] vs 68.4% [2020-2023]; p for trend<0.001). There was an increased occurrence of stable results without any deterioration at one-year follow-up (63.6% [2009-2013] vs 74.4% [2020-2023]; p for trend=0.03). CONCLUSIONS: Findings from the PRIME-MR registry highlight substantial reductions in residual MR severity and complication rates over time in PMR patients undergoing M-TEER.