Figure 1 – Follow-up overall mortality (Kaplan–Meier survival curve)
Discussion
The Perceval ® prosthetic valve (Sorin Group,
Saluggia, Italy) has been increasingly used in European cardiac surgery
centers for treatment of aortic valve disease since its first reports in
2007. As a truly sutureless bioprosthesis with proven excellent
hemodynamic outcomes, safety and marked reduction in aortic
cross-clamping and CPB times, it has been shown to reduced postoperative
morbidity and mortality as well as cost reduction of up to 25% when
compared to conventional biological heart valves (8,20), especially when
treating older patients and in those with comorbidities. However,
several questions are yet unanswered, especially regarding long-term
durability, endocarditis risk, and the need for postoperative PPI.
In our retrospective study, we sought out to assess the clinical and
hemodynamic performance, safety, and durability of the Perceval® valve for isolated AVR and in concomitant
procedures.
Our cohort is composed essentially by elderly patients, with an average
overall age of over 77 years and a small standard deviation of
approximately 5 years. Additionally, most patients had one or more
preoperative risk factors and/or comorbidity, with an average
in-hospital mortality risk measured by an EuroSCORE II of almost 3%,
despite the majority having preserved LV function.
The overall total surgical time, aorta cross-clamping and CPB times took
into consideration the surgeries where reimplantation of the valve was
necessary. The times obtained represent a significant reduction in
comparison to the mean aorta cross-clamping and CPB times of 78 and 106
min reported in conventional AVR, according to the Society of Thoracic
Surgeons database. This major reduction of over 50% in both times could
translate into improved clinical results, especially in patients with
comorbidities such as diabetes mellitus (7) or in a medium-high surgical
risk profile, as aortic clamping and CPB times are considered
independent predictors of morbidity and mortality in heart surgery (10).
The Perceval ® valve was successfully implanted in
98.99% as in 2 cases (2/198 = 1.01%) conversion to conventional
bioprosthesis was required due to valve migration. One way of possibly
reducing the likelihood of these events is by strictly obliging the
manufacturer’s preoperative echo-doppler aortic root evaluation
recommendations (a patient is suitable if the ratio between the diameter
of the STJ and the annular diameter is ≤ 1,3) (21).
In 4 cases (2.04%) reimplantation was necessary to readjust the valve,
due to minor misplacement and/or paravalvular leaks found in the
intraoperative transesophageal echocardiography, which is paramount to
assure correct placement and function. Reimplantation through the
“x-movement” technique, allowed an “en bloc” bioprosthesis
excision, simple re-folding and easy reimplantation of the valve without
damage to the leaflets or the bioprosthesis structure. (22). Reasons for
these misplacements are still unclear but in one of the cases, migration
followed cardiac manual manipulation due to additional manual de-airing.
(23).
In our study, we report no significant paravalvular leaks, a result
below the already low 1-2% commonly observed in trials with the
Perceval ® valve (6). In comparison, TAVI causes a
greater number of moderate-to-severe paravalvular leaks (7-12%),
followed by conventional AVR (1,9%), which at 2 years have been shown
to be independent predictors of mortality (10,24). Consequently, correct
measurement, placement and final visual confirmation of correct valve
placement could help avoid these complications.
The most common immediate postoperative complications (Table 3) were in
line with the expected for a major cardiac procedure. The relatively
high rate of postoperative aminergic support might be related to the
fluid restriction protocol used in our department. New-onset atrial
fibrillation is usually multifactorial and is the most common
dysrhythmic complication occurring after any cardiac surgery, affecting
typically between 30% and 50% of the patients, more than we report
(25). Although the incidence of acute kidney injury is relatively high
(10,5%), only a reduced number of patients required renal replacement
technique (3,1%).
The overall incidence rate for PPI of 12.8% is within the interval
incidence described in the literature, of 3.1% (26) to 17% (27)
although it is above rates for conventional bioprosthesis reported of
3.0 to 11.8% (28) and comparable to the ones reported for TAVI (29).
Current best available evidence suggests baseline conducting system
disease is the most powerful independent predictor of PPI requirement
following AVR. Other patient-related predictors are advanced age,
annular calcification, (27). Operative-related factors such as
incomplete decalcification of the aortic ring, valve oversizing, valve
and guiding sutures position, reoperations, longer perioperative CPB
time, and procedural implanting steps and sizing’s learning curve effect
are also important (13). In our center, all patients were operated on or
supervised by an experienced surgeon in this procedure. That said,
standardizing the implantation technique could offer benefits in
reducing the PPI incidence.
We report one case of valvular thrombosis (0.51%), which was
successfully treated with oral anticoagulants (Vitamin K antagonist).
Following the procedure, all patients received antiplatelet treatment
according to the standard protocol in use in our center, consisting of
acetylsalicylic acid or clopidogrel for a period of 3 to 6 months when
sinus rhythm was present. Antiplatelet and anticoagulation management
after sutureless valve placement is not standardized, as no specific
recommendations have been made in recent guidelines (17).
We found no structural valve deterioration, endocarditis cases or
strokes up to the 5-year follow-up, presumably because the Perceval® valve allows less manipulation of the aortic root
and annulus, zero permanent contact with foreign material such as
sutures (13) and it has been shown to present high resistance against
endocarditis in comparison with conventional prostheses. Nevertheless, 5
years of follow-up is still a short time compared to the data available
for conventional prostheses of up to 25 years (30).
The mean postoperative transvalvular gradients after surgery confirm the
excellent hemodynamic performance of the Perceval ®valve, coherent with other studies (6) and significantly lower when
compared to the ones provided by conventional prostheses (28) and TAVIs
(29).
ICU and total in-hospital stay were markedly lower when compared to
reports of conventional bioprostheses (31) and similar when compared to
TAVIs (29).
Early overall mortality (in-hospital or up to 30 days after surgery) was
2.0%, below the one predicted by the initial EuroSCORE, in line with
the 2.8% reported for conventional prostheses and significantly lower
than with TAVIs (10,30,32,33). Of the four patients who died, none of
their deaths was caused directly from a failure in the prosthetic valve
or the procedure themselves (cardiogenic and septic shock, neurological
complications). These results show good short-term clinical outcomes
despite the risk profile and advanced age of the cohort.
Overall cumulative survival at 1, 3 and 5 years and the correspondent
Kaplan-Meier curve are the ones expected taking into consideration our
cohort’s age, comorbidities, and type of interventions. It is up to par
with the mean corresponding cumulative survival of conventional AVR (34)
and better than with TAVIs up to 2 years (29), showing safety of use and
good mid-term durability, with no structural valve deterioration.
Additionally, the Perceval ® valve enables
standardization and simplification of MIS approaches, in a way
conventional prostheses have not yet made possible. MIS is associated
with a significant technical difficulty due to reduced visualization
that increases aortic cross-clamping and CPB time, extending the
learning curve (10).