Abstract
BACKGROUND
Early structural valve deterioration (SVD) frequently occurs in Mitroflow aortic bioprosthesis, especially for small sizes (19-mm and 21-mm), and it is associated with reduced overall survival. Treatment by percutaneous valve-in-valve (ViV) implantation is considered a challenging procedure. This is mainly due to an elevated risk of coronary ostia obstruction and high residual post-procedural mean gradients (mG), particularly when severe pre-existing patient-prosthesis mismatch (PPM) is present.
PURPOSE
Aim of our study was to assess the feasibility of transfemoral ViV in small Mitroflow aortic valves using supra-annular self-expanding valves, named CoreValve and Evolut R and Acurate neo and report the midterm clinical results by comparing serum natriuretic peptide type B levels (BNP) before the procedure and at a mean follow-up of 2 years.
METHODS
This is an observational study including 11 patients with stenotic-type SVD of small Mitroflow aortic valves, considered at high/prohibitive risk for surgical reoperation, who underwent ViV implantation between July 2012 and March 2018. We performed echocardiographic assessment of valve hemodynamics (according to VARC-2 definitions) before and after the procedure and during the follow-up. We used the BNP ratio (the ratio between measured serum BNP/NT-proBNP level and maximal normal level) to compare BNP results before the procedure and at follow-up. All-cause mortality during the hospitalization and follow-up was also reported.
RESULTS
The Mitroflow size was 19-mm in 4 patients and 21-mm in 7 patients. Pre-existing severe PPM was present in 4 patients and moderate PPM in 7. CoreValve 26 was implanted in 2 patients, EvolutR 23 in 5 and Acurate neo S in 4 patients. We reported no coronary obstruction, deaths or other major events during the hospitalization. At a mean follow-up of 2 years one patient died. The baseline aortic mG of 56 ± 19 mmHg has significantly reduced after the procedure to 16,6 ± 8 mmHg (p < 0.0001) and follow-up 29,6 ± 16 mmHg (p = 0.008). A post-procedural mG≥20, but <40 mmHg, was observed in 3 patients. BNP ratio at baseline was 14,6 ± 12; only one patient had a BNP ratio <3. At follow-up (n = 7 patients), BNP ratio was significantly lowered to 1,5 ± 1,08 (p = 0.01) with only one patient with a BNP ratio >3. Patients with mPG ≥20 mmHg did not show differences in terms of mortality and reduction of serum BNP levels.
CONCLUSIONS
In our experience the ViV procedure on small degenerated aortic Mitroflow bioprosthesis appears to be technically feasible and provides good midterm clinical results with a net reduction in serum BNP levels, although an increase in mG was observed. Even though a post-procedural mG ≥20 mmHg is considered indicative of suboptimal aortic valve hemodynamics (according to VARC-2 criteria), its correlation with worse outcomes remains unclear and deserves further investigations.
Valve-in-Valve Implantation of Medtronic CoreValve Prosthesis in Patients with Failing Bioprosthetic Aortic Valves