Discussion.
Reoperation for mitral bioprosthesis failure is associated with increased mortality and morbidity.1 According to the recent data from the Society of Thoracic Surgeon (STS), American College of Cardiology and Transcatheter Valve Therapy Registry including 1529 patients with a mean STS score of 11.1% and a mean age of 73 years, TMViV for mitral bioprosthesis failure is an attractive alternative2. Indeed, procedural success (96.8%) was high and all-cause mortality at 30 days was 5.4%. The transseptal approach became more and more dominant during the inclusion period compared to transapical approach (overall 86.7% of transseptal approach) and is associated with a lower 1-year mortality rate (15.8% versus 21.7%, p=0.03). Table 1 summarizes the largest series reporting TMViV for degenerated bioprosthesis2–9 considering procedural success, rate of transseptal approach, Edwards THV sizes, post procedural mean gradient, rate of LV outflow tract obstruction and all-cause mortality.
With respect to our case, we clearly favored the transseptal over transapical approach considering the reduced LVEF. Technically, the use of the Agilis steerable transseptal sheath is recommended to provide enough support to advance the stiff guidewire into the LV. When using the usual SL0 transseptal sheath (Abbott Vasc), the pigtail repeatedly moved out from the LV while advancing the stiff Safari guidewire.
In the largest registry from Whisenant et al, a mean gradient of 6.9 mmHg was found at one year for valve sizes of 26 and 29 mm, which is similar to our patient, but superior to what we can expect after conventional surgery. The SAPIEN S3 THV is FDA approved for TMViV for mitral bioprosthesis since June 2017. However, unanswered questions remain with respect to the elevated residual mean gradient and its effect on valve durability and potential valve thrombosis10. Additional studies are required to define the optimal anticoagulant therapy in the absence of atrial fibrillation as well as long term outcomes.