Comments
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.