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Page 6 of 20 Nappi et al. Vessel Plus 2021;5:40 https://dx.doi.org/10.20517/2574-1209.2021.06

[10]
Two years later, Elmariah et al. , using fluoroscopic and echocardiographic guidance, described the
successful implantation of TMViV through the left ventricular apex. The authors implanted a 26-mm
Edwards SAPIEN heart valve (Edwards Lifesciences) that was accurately placed within the previous
stenosed mitral 27-mm bioprosthesis Carpentier Edwards Perimount (Edwards Lifesciences, Irvine,
California). Surgery with a conventional standard approach was not recommended for the patient because
he presented numerous comorbidities including cerebrovascular disease [95% stenosis of the left internal
carotid artery (ICA) and moderate stenosis of the right ICA]. He had undergone a previous coronary artery
bypass grafting (CABG)/MVR which was complicated with a dehiscence of the sternal wound requiring
complex reconstruction and had received recent percutaneous coronary intervention. Moreover, the patient
was managed with bilateral renal artery stenting.

[35]
Simultaneously, Seiffert et al. reported the improved outcome using the transapical TMViV implantation
in 6 patients. The amelioration of the clinical condition is almost certainly due to rapid improvement in
hemodynamics, as testified by the reduction of the mean transvalvular gradients [from 11.3 ± 5.2 mmHg to
5.5 ± 3.6 mmHg (P = 0.016)] and median MV regurgitation {from grade 3.0 [interquartile range (IQR): 2.7-
3.1] to 0 (IQR: 0-1.0); P = 0.033}. Patients were checked over a median follow-up of 70 days (IQR: 25.5-358
days), showing an increased functional status with median NYHA functional class [from 3.0 (IQR: 3.0-3.5)
to 2.0 (IQR: 1.5-2.0); P = 0.048]. A different approach from the transapical one, however, remained a
primary objective.

[11]
A few years later , the first 4 consecutive patients successfully received a transcatheter mitral valve
replacement for the treatment of degenerated mitral valve bioprostheses that included both bioprosthetic
valves (n = 2) or rings (n = 2) and using the transseptal access. The cornerstone of this report was to
highlight how the innovative transcatheter mitral valve replacement technique could be performed using
transvenous and transseptal mitral valve replacement. The authors, demonstrating the feasibility of the
procedure with only femoral venous approach, stated the reduction of complications and length of hospital
stay in TMViV-T recipients compared to those who were managed with transapical access or redo
surgery [5,31] .

The percutaneous transvenous transseptal approach was reported in one study including 48 high-risk
patients with a median follow-up of 40 days (range: 1-491 days) and the mean Society of Thoracic Surgeons
(STS) risk score was 13.2% ± 7.4% with a mean age of 76 ± 11 years [14,18,27,28] . Patients were managed using an
Edwards SAPIEN prosthesis (Edwards Lifesciences, Irvine, California) and received TMViV/R therapy for
33 degenerated mitral bioprostheses, 9 previously failed annuloplasty and 6 severe MAC. Considering the
overall group of patients undergoing treatment, it is important to underline that efficacy was achieved in 42
of 48 patients (88%). In detail, the success rate was reached for 94% (31 out of 33) of patients who
underwent the mechanical intervention for the failed bioprosthetic mitral, whereas it was 73% (11 out of 15
patients) for those with failed annuloplasty rings and MAC [14,15] .

While awaiting the outcome of large series of multicenter registry studies, there is currently an
unremarkable amount of evidence to sustain the use of percutaneous transfemoral antegrade transseptal
implantation for mitral prostheses, even though this may provide an encouraging survival benefit over a
standard Re-MVS. Indeed, more than 7 years ago, a cohort of 23 patients was studied with a median follow-
up greater than 2 years revealing a Kaplan-Meier survival rate of 90.4% [9,20,36,37] .

Only one independent study has confirmed this finding in a larger cohort and with the use of transseptal
balloon-expandable TMViV-T. The study reported the results from 87 patients, of whom approximately