Increased institutional experience with transcatheter mitral valve repair (TMVr) with MitraClip is associated with improved procedural success, shorter procedure times and fewer complications, according to a study published July 15 in JACC: Cardiovascular Interventions.

Adnan K. Chhatriwalla, MD, FACC, et al., used the STS/ACC TVT Registry to examine the association between institutional experience and outcomes in 12,334 patients who underwent TMVr with MitraClip at 275 sites. The researchers looked at hospital volumes and their effect on procedural success, procedure time and procedural complications by stratifying procedures into three tertiles based on institutional case sequence and examining baseline demographics, procedural data and complications across all tertiles. The study’s primary outcome was in-hospital procedural success. Procedural complications were analyzed individually and as a composite.

According to the results, “optimal” procedural success – defined as ≤ 1 + residual mitral regurgitation (MR) without mortality or need for cardiac surgery – increased across tertiles of case experience, with 62.0 percent in the lowest-performing tertile, 65.5 percent in the middle tertile and 72.5 percent in the highest-performing tertile. Procedural time and complications decreased based on institutional case experience. In addition, “acceptable” procedural success – defined as ≤ 2 + residual MR without mortality or need for cardiac surgery – increased based on institutional experience, with rates of 91.2 percent, 91.2 percent and 92.9 percent for the lowest-performing, middle and highest-performing tertiles, respectively. The researchers noted improvements in procedural success, procedure time and procedural complications after an institution performed about 50 cases, with continued improvement up to 200 cases.

An increase in institutional experience with TMVr with MitraClip is associated with improved outcomes, the researchers note. They suggest that a “relatively greater attention to case selection may be important during an institution’s early case experience,” concluding that additional research is needed to “understand the specific factors associated with site experience that impact long-term clinical outcomes.”

In an accompanying editorial commentary, Gregg W. Stone, MD, FACC, writes that the study “provides novel insights into the relationship between institutional MitraClip volume and in-hospital outcomes.” Additional research is needed to “guide subspecialty and societal decision-making regarding the optimal number of mitral centers of excellence and operators, and the minimal number of procedures required to achieve and maintain an acceptable level of competence, let alone excellence.”

Keywords: Mitral Valve Insufficiency, Mitral Valve, Registries, Cardiac Surgical Procedures, National Cardiovascular Data Registries, STS/ACC TVT Registry

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