Nowadays in the post POPULAR-TAVI era, after transcatheter aortic valve replacement (TAVR),
an establish uniform approach towards anticoagulation and antithrombotic therapy were
established.
All patients undergoing TAVR without other indication to dual antiplatelet therapy (DAPT) or
oral anticoagulation (OAC), were currently treated according with the general concept of
"less is more" (only single antiplatelet therapy - SAPT or only oral anticoagulation - OAC)
[1-3].
By comparing the frequency of ischemic and bleeding events, data from trial revealed that the
bleeding events were more frequent than the ischemic one despite the level of surgical risk,
however a gradient of reduction in terms of difference was seen from the highest to the
lowest risk profile [4].
Furthermore, recent literature showed how the timeframe analysis approach, giving the
possibility for a complete time variability evaluation, is able to visualize the fluctuation
of the risk over the time. Unfortunately, no stratified data according with the surgical risk
level, are available using this approach [5].
Moreover, despite these results that highlight the relevance of the patient's background on
the occurrence of ischemic and bleeding events, a tailored antithrombotic strategy remains
unexplored and all patients undergoing TAVR without other indication to DAPT or OAC, were
currently treated with a uniform approach in terms of intensity during the time (1-3).
1.1. Assessment of ischemic and bleeding risk after TAVR according with antithrombotic
therapy and surgical risk The rate of adverse thrombotic and hemorrhagic events occurred in
the first days after the procedure, were mainly driven by the TAVR's access bleeding and the
periprocedural stroke.
Recent study, using the average daily risk analysis, showed the prevalence of the ischemic
risk in the first 30 days after the procedure followed by a rising of the bleeding one which
become predominant during the follow up, affecting the long-term prognosis [5].
However, only data based on surgical risk derived from the 'first time event approach' are
available in the literature and none of them investigates whether the higher expected risks -
both ischemic and hemorrhagic - in the highest risk cohort remain high even months after
TAVR.
Bearing this in mind, these observations revealed that ischemic and bleeding events are not
evenly distributed over time, suggesting that a risk-based modulation of the antithrombotic
therapy could be better capture the time-dependent evolution of the phenomena. Experience
from several studies on antithrombotic therapy in the PCI field, have focused on the
intensity and the timing of administration, while no such evidence exists in the field of
TAVR (6-7).
Thus, the comprehension of this phenomena holds the potential benefit of a tailored
antithrombotic therapy guided by an integrated approach based on the trend of ischemic and
bleeding risk stratified according to the patient's risk profile and the antithrombotic
regimen adopted.
1.2. Impact of prostheses type and complete blood count variables on ischemic and bleeding
events As the same of patient's features and periprocedural variables, it is possible to
assume that also the prostheses characteristics in terms of type of leaflet (porcine vs
bovine), stent frame amount (short frame versus long frame) and the number of they
(valve-in-valve), are not fully investigated previously and may play a role in the thrombotic
and hemorrhagic adverse events occurrence.
Understanding the impact of structural and functional valve's characteristics on the bleeding
and ischemic risk among patients who undergo TAVR, may have important implications in
prosthesis and antithrombotic therapy selection and needs to be investigated properly with a
"repeated-event" analysis.
Moreover, also the frequent phenomenon of anemia and thrombocytopenia after TAVR, were
identified from several studies as predictors of poor outcome up to 1 year follow up even
with a perfect prosthesis function and despite the mechanism behind, it's not completely
understood (8). According to these data the relationship between blood count abnormalities,
type of prosthesis and ischemic and bleeding risk have never been explored.
The identification of predictive variables leading to the development of anemia and
thrombocytopenia and their impact on the risk of hemorrhagic and thrombotic events, might
allow us a tailored selection of prosthesis, antithrombotic strategy and procedural planning
in order to potentially reduce the risk of adverse events.
1.3. Dynamic therapeutic changes after TAVI Several studies investigated the impact of
different antithrombotic strategies on outcomes and prosthesis performance by comparing
different approaches in combination. However, most of them assessed the clinical endpoints
considering only the discharge therapy, with a lack of real data in terms of regimes
switching and duration of any effective treatment prescribed.
The assessment of these data during follow-up, remains underexplored even though their
availability could potentially allow an accurate definition of the ongoing strategy at the
time of adverse event occurrence. Moreover, the collection of these variables may provide
important information about the antithrombotic management, including the reason, the rate and
the timing of crossover for each treatment.
Finally, given the evolution of the antithrombotic strategy in the last years, in particular
in the pre and post Popular TAVI era, and knowing the therapeutic management during the first
year of follow up, it's possible to define the impact of any study/trial on the real-world
approach in recent years.