Clinical impact of residual gradient and 3D orifice area after trans-catheter mitral valve-in-valve implantation.

Aims: The mitral-valve-in-valve (MVIV) procedure has emerged as an important therapy in failing surgical bioprosthetic valves. We aimed to evaluate factors associated with outcome following MVIV intervention, specifically the impact of 30-day MVIV gradient. We also explored the value of intraprocedural MVIV 3-dimensional-anatomic orifice area (3D-AOA) by transesophageal echocardiography (TEE) in a subset of patients (n=68).

Methods and results: Consecutive MVIV patients from a single institution with 30-day transthoracic echocardiography (TTE) were included (N=100). Clinical and echocardiographic variables were evaluated. The primary outcome was one-year composite of all-cause mortality, heart failure hospitalization or reintervention. Multivariable analysis was performed to determine predictors of primary outcome. Mean age was 77.3±10.6 years and pre-intervention mean mitral gradient was 11.5±4.0 mmHg. 30-day MVIV mean gradient was 7.4±2.6 mmHg with ≤1+ residual regurgitation in 99.0% of patients. Multivariable analysis identified MVIV mean gradient as the only independent determinant of the primary outcome (HR 1.31, CI 1.07-1.61, p=0.009). MVIV 3D-AOA was associated with a 30-day MVIV mean gradient of > 7 mmHg by TTE (ROC-AUC 0.8, p<0.001), and patients with 3D-AOA >2 cm2 had significantly lower 1-year all-cause mortality (2.5% vs. 18.7% Kaplan Meier log-rank p=0.03).

Conclusion: Elevated 30-day mean gradient is associated with worse outcomes after MVIV, and smaller intraprocedural MVIV 3D-AOA is associated with a higher 30-day mean gradient and worse mortality. Optimizing MVIV orifice area at the time of procedure may improve valve hemodynamics and patient outcomes.