Transcatheter valve-in-valve implantation in a degenerated very small Mitroflow prosthesis.

OBJECTIVES: To assess the feasibility and results of 'valve-in-valve' implantation using the 23-mm CoreValve for the treatment of degenerated 19-mm and 21-mm Mitroflow bioprostheses.
METHODS: We retrospectively analysed all consecutive patients who underwent transcatheter aortic valve implantation for 19-mm and 21-mm Mitroflow bioprostheses. The height of implantation with respect to the ring of the Mitroflow prosthesis was targeted at -6 mm for the first 3 cases. In the following cases, the target was higher to promote free supra-annular movement of the leaflets.
RESULTS: The procedure was successful in 17 of 18 patients (94%). For implantations above the limit of -6 mm, the mean gradient was 10.4 ± 2.6 mmHg compared with 28.1 ± 11.6 mmHg for implantations below the limit of -6 mm (P < 0.01). For patients with severe stenosis as main mechanism of failure of the bioprosthesis, the mean post-procedural gradient was 31.2 ± 11.8 mmHg compared with 12.7 ± 6 mmHg in the absence of severe stenosis (P < 0.01). Patient-prosthesis mismatch (indexed effective orifice area ≤ 0.85 cm2/m2) and severe mismatch (indexed effective orifice area ≤ 0.65 cm2/m2) were present in 83% (15 of 18) and 27% (5 of 18) of patients, respectively. We did not notice any complications following the procedures. Six months after the procedure, functional status was improved in all patients.
CONCLUSIONS: Our short series demonstrates the ability to perform transcatheter 'valve-in-valve' implantation in 19-mm and 21-mm Mitroflow prostheses with satisfactory results, but high post-procedural gradients and patient-prosthesis mismatch remain a relatively frequent problem mostly when severe stenosis is the main mechanism of failure. Implantation in a high position is critical to decrease the rate of high postimplantation gradients.