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MAC is among the most challenging problems in cardiac surgery. It can
lead to poor outcomes and serious issues such as PPM. Patients with
severe circumferential MAC are frequently not suitable for transcatheter
MV replacement and outcomes after percutaneous valve in MAC (ViMAC) are
disappointing (2). Additionally, these patients are often judged to have
no surgical alternative. Hence, decision making in those high-risk
patients could be tremendously difficult. Therefore, MV procedures in
those patients should always be discussed by a “Heart Team” and should
be preferably performed in high-volume “Heart Valve Centers”.
Several alternative techniques offer the possibility of implanting
accurately sized MV bioprostheses in patients with MAC, thus avoiding
the negative effects of PPM. Surgical ViMAC through direct open atrial
access is an option with excellent outcomes (3). It allows removal of
the anterior mitral leaflet under direct view in order to minimize the
risk of left ventricular outflow tract obstruction (3). Alternatively,
based on the same concept, the LAMPOON transcatheter technique splits
the anterior mitral leaflet percutaneously prior to transcatheter ViMAC
(4).
Transcatheter mitral ViV procedures have excellent outcomes in high-risk
patients with degenerated mitral bioprostheses (2,5). Nevertheless,
transcatheter methods are only possible if anatomy is deemed to be
favorable (2,5,6).This is not the case in this patient, who presented
with severe prosthetic MV stenosis of a very rapidly degenerating mitral
prosthesis, which originally resulted in mitral PPM. Accelerated
structural valve deterioration is known to occur in patients with PPM
due to turbulent blood flow through the bioprosthesis (7). Hence, PPM
can only be addressed by implanting a new MV prosthesis with a greater
effective opening area. Therefore, transcatheter mitral ViV replacement
was in this case only a palliative strategy to ephemerally improve
quality of life in a highly symptomatic patient, whose structural heart
disease further worsened due to persistent severe PPM.
In conclusion, PPM must be prevented through the use of alternative
techniques that allow implantation of adequately sized MV prostheses in
patients with MAC. PPM should be recognized as a contraindication for
transcatheter mitral ViV replacement.