Association of Site Volume and MitraClip Outcomes in Secondary Mitral Regurgitation

The number of sites performing transcatheter edge-to-edge repair (TEER) for secondary mitral regurgitation (SMR) has increased. Despite concerns that low-volume sites may have worse outcomes, data are limited on the association between site volume and TEER outcomes. This study aimed to assess the association between site volume and mitral TEER outcomes in SMR. The COAPT PAS (COAPT Post-Approval Study) included patients with SMR who underwent TEER with the MitraClip device from March 2019 to September 2020 following Food and Drug Administration approval. Sites were categorized by number of patients treated: low (≤25), medium (25-50), and high (>50). Of 5,000 patients, 2,632 were from low-, 1,527 from medium-, and 841 from high-volume sites. High-volume sites treated sicker patients with higher Society of Thoracic Surgeons scores and prior heart failure hospitalization rates. Procedures at low-volume sites had similar device implant rates (low: 97%, medium: 99%, high: 98%), used fewer number of clips (low: 1.4 ± 0.6, medium: 1.5 ± 0.6, high: 1.6 ± 0.7 clips, P < 0.001), and had longer device (low: 68 ± 55, medium: 56 ± 53, high: 57 ± 42 min, P < 0.001) and procedure times (low: 153 ± 67, medium: 131 ± 59, high: 128 ± 56 min, P < 0.001). Technical success was comparable (low: 93%, medium: 94%, high: 95%, P = 0.92). MR reduction to ≤2+ and ≤1+ was also similar. There was no difference in heart failure hospitalization (low: 19%, medium: 18%, high: 20%, P = 0.50) or all-cause mortality (low: 23%, medium: 21%, high: 20%, P = 0.27). Technical success, MR reduction, and 1-year clinical outcomes were comparable across volume strata during the early adoption phase, without significant differences between low- and high-volume centers.