Discussion:
The optimal surgical treatment for MVR remains under debate. The latest
reports demonstrate MV repair is considered to be superior to
replacement (7, 16). The excellent outcomes of surgical repair with a
recommendation of risk stratification and earlier intervention when the
probability of durable repair is high show low operative mortality and
morbidity rates (2, 4, 7). In view of these findings, the rate of MV
repair in Germany increased from 37.6% to 62.8% between 2000 and 2015
(17). These findings however remain debatable considering reports
showing a benefit for preventing recurrence of MVR and rehospitalization
with MV replacement. We decided to analyze our institutional results
comparing repair and replacement using a propensity-matched analysis to
homogenize the treatment groups and to perform a detailed statistical
comparative analysis.
The age of a patient has long been considered an independent predictor
of MV replacement (18). Silaschi et al. (19) showed patients who
underwent MV repair were older compared to the replacement group.
Thourani et al. (20) found that survival in the repair group was
significantly higher than that in the replacement group in patients
younger than 60 years, whereas this difference was not visible in
patients older than 60. In our study, propensity-score matching was
performed prior to analyze, with age being one of the baseline
variables.
Vassileva et al (18) demonstrated that patients who had diabetes
mellitus, myocardial infarction, stroke, previous cardiac surgery,
and/or previous PCI in their history had a tendency to undergo
replacement. In our study, the forementioned characteristics as well as
the EuroSCORE II were similar between the two groups. In light of this,
we believe that the decision against repair should not be based on the
patient’s age or history.
It is known that many factors are affecting the short and long-term
outcomes of MV surgery. In our study, by performing a univariate
logistic and multivariate regression analysis, we found that patients
with CAD, or a history of it, had increased risk of in-hospital
mortality. That could be due to reduced heart function as a result of
the disease, and the acute side effects of CPB and cardioplegia which
may cause an impairment in heart function in the first few hours after
surgery, thus increasing the probability of developing low-cardiac
output syndrome and the respective impact. Similar to Carino et al (13),
our study showed that a high EuroSCORE II was associated with an
increased 30-day mortality and higher adverse long-term outcomes.
EuroSCORE II is widely considered an important predictor for 30-day
mortality after cardiac surgery. It was validated in some studies in
patients undergoing MV surgery (13, 21, 22) but we only found one study
that explored the ability of EuroSCORE II to predict the 30-day
mortality in patients undergoing MV surgery. They found that EuroSCORE
II overestimates 30-day mortality (13).
Some surgeons believe MV repair is more complex, requiring longer
X-clamp time and having a higher risk of recurrence (19). In our
analysis, we observed that the difference between the two groups in CPB
and X-clamp time were not statistically significant. These results were
in agreement with the findings of Silaschi et al. (19) and Chivasso et
al. (23), In contrast, Farid et al. (24) showed that patients who
underwent repair have had shorter CPB and X-clamp times compared with
those who underwent replacement. We know that cardiac and operative
trauma can be reduced when CPB and X-clamp time are shorter, depending
on the surgeon’s experience.
In this study, we observed two cases of ring dehiscence requiring
re-surgery. This complication after atrioventricular valves repair,
particularly after MV repair, is not rare and is reported in 13–42% of
procedural failures in MV annuloplasty repair (25). This complication
led us to implement a modified approach by placing four pledgeted
sutures on the A1, A3, P1 and P3 segments to reinforce the stability of
the ring. Since using this strategy, we have not observed any new cases
of ring dehiscence in our patients also those who not included in this
trial.
The AATS Guidelines, AHA/ACC and ESC recommend repair to treat severe
degenerative and ischemic MVR (2, 4, 26). The evidence for this
recommendation is derived from single-center studies; however, the
superiority of MV repair led the guidelines to consider the low
probability of achieving a durable repair. This served as a reason to
pass patients to specialized MV repair centers (2, 4). Some
retrospective studies have reported some advantage of repair, in
particular the operative mortality was lower compared to that of
replacement (27-30). However, there is a multitude of studies showing no
evidence for a preference of one intervention over the other (10, 16,
20, 28, 31).
This clinical investigation demonstrates that patients undergoing repair
have similar mortality within 30 days after surgery, but lower mortality
after 5 years compared with patients undergoing replacement.