Discussion
Valve-in-valve (ViV) procedures have become a viable alternative to treat high risk redo surgical patients either in the aortic and mitral position. There are sparse reports of staged or concomitant transfemoral or transfemoral and transeptal replacements. [2,3]
Several technical aspects must be considered. On the aortic side it is mandatory an accurate valve sizing to reduce the risk of patient-prosthesis mismatch (PPM) and to guarantee a maximal valvular sealing; for a balloon-expandable device it is generally recommended a 1 mm minimum oversizing respect the internal stent diameter of the failed bioprosthesis.
Regarding the mitral replacement, the key aspects for a successful implantation are the correct sizing (similar to the aortic one) and the correct height of implantation to reduce the risk of atrial valve migration or left ventricular outflow tract (LVOT) obstruction. On this regard, an acute mitro-aortic angle < 115 degrees and a neo-LVOT area less than 250 mm2 are commonly considered as pre-procedural risk factors for LVOT obstruction. [4]
In this case we decided to perform the staged two-steps approach following these considerations.
We have firstly replaced the aortic bioprosthesis to relief the afterload, improve cardiac output and diastolic coronary perfusion (CT evidence of moderate proximal left anterior descending stenosis).
Secondly, the patient presented with a severely depressed LVEF thus we preferred to postpone the transapical approach to let some degree of ventricular improvement In fact, the first postoperative echocardiogram showed an increased left ventricular ejection fraction (EF 35%). Due to the persistence of small left atrial dimensions although permanent atrial fibrillation we chose to not pursuit the transseptal approach and we planned a standard transapical route.
Finally, the delayed second procedure allowed us to re-assess the geometrical relationships between the mitro-aortic struts and choose the optimal site of transapical approach for better mitral co-axiality.
In conclusion, patients with previous history of mitro-aortic surgery can be very challenging in case of either redo surgery or transcatheter replacement, due to the biological prosthesis’s relationships, although there is still a lack of a specific risk score [5] for this particular cohort of patients.
An in-depth geometrical preoperative and postoperative investigation has proven to be a useful and reproducible tool leading to optimal technical and at the end clinical outcomes. We strongly believe that in the structural heart interventions field a close patient-to-patient approach in a qualified heart team is the only way to perform high quality procedure with low grade of risk, in a high-level healthcare service.