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

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 three-dimensional anatomic orifice area (3D-AOA) by transoesophageal echocardiography in a subset of patients (n = 68).

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 re-intervention. 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. Thirty-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).

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 haemodynamics and patient outcomes.