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Page 2 of 16 Annibali et al. Mini-invasive Surg 2022;6:12 https://dx.doi.org/10.20517/2574-1225.2021.101

management of symptomatic severe aortic stenosis. TAVR has now been approved in patients with severe
symptomatic aortic stenosis across all surgical risk profiles and for patients with failed bioprosthetic valves
(BVs). Valve-in-valve (ViV) TAVR has emerged as an alternative to surgical aortic valve replacement
(SAVR) in patients at high operative risk, now accounting for approximately 5% of all TAVR procedures
performed in the United States . BVs are increasingly being used for young patients, at the expense of
[1]
mechanical valves, and this will result in a major increase in reinterventions in the next future. Data
currently available from large registries are encouraging in terms of safety and long-term survival with one-
[2-4]
year survival rates exceeding 80% .
To identify a dysfunctional valve, in 2017, a consensus document from the European Society of
Interventional Cardiology (EAPCI), the European Society of Cardio-Thoracic Surgery, and the European
Society of Cardiology defined structural valve deterioration as: (1) mean gradient ≥ 40 mmHg and/or ≥ 20
mmHg change from baseline (before discharge or within 30 days of valve implantation); and/or (2) severe
[5]
new or worsening intra-prosthetic aortic regurgitation . More recently, in the Valve Academic Research
Consortium (VARC)-3, four main categories of aortic bioprosthetic dysfunctions have been defined, based
on the main etiopathogenetic mechanisms: structural valve deterioration (SVD), non-structural valve
deterioration (NSVD) (e.g., paravalvular regurgitation and prosthesis-patient mismatch), thrombosis and
[6]
endocarditis .
ViV TAVR is more complex than native valve TAVR and should ideally be performed by experienced
[7,8]
teams after a multidisciplinary decision in the heart team according to the latest guidelines . Therefore, a
standardized approach and a meticulous pre-procedural planning are the keys to success. The purpose of
this review is to give a contemporary overview regarding the current and future challenges of this
procedure.

CHOOSING THE BEST TREATMENT FOR DEGENERATED BIOPROSTHESIS
Although, to date, there are no data from randomized trials regarding the best treatment of SVD, data from
meta-analyses have demonstrated a lower incidence of postoperative complications and 30-day mortality
with similar one-year and midterm mortality rates for TAVR ViV compared with redo SAVR, despite
increased rates of major bleeding, myocardial infarction and severe prosthesis-patient mismatch [9-11] .

ViV TAVR is currently the treatment of choice for patients with degenerated surgical BVs considered to be
at high or extreme risk for a redo SAVR. In contrast, redo SAVR remains the first choice in patients at
intermediate or low surgical risk unless there are unfavorable anatomies (e.g., calcified aortic root or hostile
chest). Younger age (< 75 years old), thus greater life expectancy, and unfavorable coronary anatomy due to
high risk of coronary artery obstruction should be considered predisposing factors toward redo SAVR given
the current lack of long-term data regarding ViV TAVR. Other features in favor of redo SAVR are the
presence of a severe paravalvular leak or small BVs with severe prosthesis-patient mismatch in which
percutaneous closure or bioprosthesis fracture are not feasible .
[12]

BIOPROSTHETIC VALVE CHARACTERISTICS
Obtaining information about the type of surgery performed and the characteristics of the implanted valve
are the first fundamental steps in preparing for the procedure. There are two main groups of bioprosthetic
surgical valves: stented and stentless surgical devices [13,14] . Stentless valves, representing approximately 20%
of patients with ViV, most frequently present with regurgitation as a modality of degeneration, with lower
postprocedural gradients than those observed with stented valves but with higher rates of periprocedural
complications as initial device malposition, second transcatheter device, coronary obstruction and