ABSTRACT
The long-term outcome of patients undergoing mitral valve repair (MVr)
is based on what happens during the more or less 60 minutes of aortic
cross clamping necessary to transform a leaking valve in a
well-functioning one. As a consequence, the experience of the surgeon
performing the procedure is the only determinant of the success rate
that deserves to be taken into account. It is clear from the literature
that the number of cases/year is inversely related to the number of
early and late deaths, of repair failures and of reoperations. However,
there is no agreement on the minimum caseload/year that represents the
threshold to identify surgeons that can perform or not MVr. This problem
then cannot be regulated by specific guidelines of by Scientific
Societies, but only by the ethical perception we have of our profession.
Mitral valve repair (MVr) for mitral regurgitation (MR) is one of the
most intriguing valvular procedures. Most surgeons are following general
rules, but there is always room for some personalization of the
techniques, an aspect that allows to reach the best results in the hands
of that particular surgeon.
On the other side, as surgeons are always reporting the results in
patients undergoing MVr, the general vision is lost. We often do not
know exactly how many patients have MV replacement (MVR) as a first
strategy, or mechanical complications (eg, mitral stenosis after
repair)1, being the outcome focused on MR return or,
more often, on MV reoperations. Moreover, the advent of minimally
invasive mitral surgery (MIMS) through a right small thoracotomy pushed
many surgeons to start a program in the hope to attract patients in an
era when the number of referrals is reducing.
All these aspects, together with the necessity to guarantee a reasonable
result to the patient, led to a discussion on some specific points. Is
MVr a procedure for all surgeons? Can all the surgeons perform MVr using
any approach? Is it necessary to limit MVr to selected Centers?
The European2 and American3guidelines recommend, in general, repair when results are expected to be
durable. However, in symptomatic and asymptomatic (with triggers)
patients, they recommend only MV surgery, not the type of intervention.
Only in asymptomatic patients without triggers MV repair is formally
recommended and both guidelines suggest that is has to be performed in a
Heart Valve Center2 or in a Center where the
possibility of repair are >95% and the operative mortality
is <1%3.
The first question is then: who has to be the surgeon for an
asymptomatic patient? A recent survey by Gammie et al4found that asymptomatic patients without triggers were only the 8.5% of
31,475 patients operated on between 2011 and 2016 in US and the repair
rate was 92% with an overall early mortality of 0.8%. It is very
likely that asymptomatic patients were already directed toward
high-volume centers (>23 cases/year). In this report only
48 Centers out of 1020 (4.7%) were high-volume centers, but their case
volume was 40.5% with a repair rate of 92% (versus 75.9% in the
remaining centers).
These observations, while show that asymptomatic patients are often
addressed to high-volume centers, on the other side rise another
problem: are the results of MVr depending on the volume of cases and
then on the experience of the single surgeon?
The prevalence of repair on patients with degenerative MR goes from 67%
to 81%5-7. Repair rate is lower in the elderly, in
women and in patients with comorbidities6. The number
of cases performed yearly by a surgeon or by a Hospital has a huge
influence not only on the repair rate, but as well on early and late
mortality5,8-10 and reoperation
rate5. A recent report from the New York State showed
that high-volume hospital increased their caseload and improved the
outcome in valve surgeries11, reinforcing the concept
that high volumes will improve results that will increase more the
caseload. In South Korea, analyzing 6,041 patients undergoing MVr,
1-year mortality was higher in low- (<20 cases/year) and
medium-(20-40 cases/year) volume centers if compared with high-volume
(>40 cases/year) centers (10.1%, 8.7% and 4.7%). The
reoperation rate was as well higher in low-volume (HR 1.86, 1.16-2.98,
p=0.010) and in medium-volume (HR 1.91, 1.30-2.82, p=0.001) compared
with high-volume centers8. Better results in
high-volume centers were confirmed by other
Authors9,12. Badhwar et al10reported, in patients with primary degenerative MR, a repair rate of
80.8%, increasing from the lowest (63.8%) to the highest volume
quartile (84.5%). The median hospital median repair volume was 11 cases
(5-25) and the median surgeon repair volume was 5 (2-11). Rate of
successful MVr were lower in the lowest quartile as well as 1-year
mortality rate, but not reoperation rate, both for hospital and surgeon
volumes. An inverse correlation was found between composite endpoint of
morbidity and mortality and volume quartile, with the results changed
when the hospital volumes reached 75 cases/year and surgeon volume 35
cases/year.
In a recent report13 analyzing the outcome of 4,420
patients operated on in Australia and New Zealand for degenerative MR
from 2008 to 2017, Wayne et al. confirmed that repair rate was depending
from caseload: 62.6% to 79.5% for lowest to highest volume surgeons
and 54.6% to 77.5% from lowest to highest volume hospitals. Surgeons
performing >10 cases per year were more likely to repair
the valve, in particular if the caseload was >20/year.
Hospitals performing >10 cases/year were more likely to
repair the valve, without any benefit over this threshold.
Interestingly, low-volume surgeons (≤25 cases/year) obtained better
repair rate if they worked in Hospitals where there was at least a
high-volume surgeon (>50 cases/year)4.
If there is general agreement that the caseload is crucial to achieve
optimal results, it is not clear from the literature which is the cut
point either for the surgeon or for the Hospital, being as low as
>10 cases/year for Hospitals13 or as high
as >50 cases/year for surgeons. Then even if many surgeons
are in favor of establishing MVr as a
subspecialty14,15, it is not a solution that can be
regulated in the short time.
Other surgical approaches were developed to repair a regurgitant MV.
MIMS has become widely used as patients feel that the cosmetic result
confers an added value to the procedure. Optimal results have been
published, but data from the real world have not been extensively
reported. A recent Nationwide survey16 analyzed the
outcome in 2,501 patients who underwent MVr between 2013 and 2018
through different approaches. In propensity score matched groups (718
each) the Authors found that patients undergoing MVr through a right
mini-thoracotomy had a lower rate of repair (76.3% versus 80.9%,
p=0.04). At 5-year follow-up, survival was similar but freedom from
reintervention was lower in patients who underwent MIMS (95.8% vs
97.4%, p=0.003). This data could be the mirror of the acceptance of a
suboptimal result at the end of the procedure.
A new technique in the field of prolapsing MV, transapical implantation
of neochords gained attention from the surgical world. However, even in
dedicated hands, this technique did not entail satisfying results. In a
propensity matched study17, in patients with a mean
age of 63 years, freedom from 5-year moderate or more MR was 57.6% in
the neochord group versus 84.6% in the conventional group
(p<0.001) and freedom from reoperation was, respectively,
78.9% versus 92% (p=0.022). The same team analyzed 100 consecutive
cases operated on from 2013 to 201618. 5-year freedom
from severe MR was 14% in patients with favorable anatomy and 63% when
anatomy was unfavorable (p<0.001), with a reoperation rate of
14.7% versus 43.4% (p<0.001).
MVr represents an ethical more than a regulatory problem, that every
surgeon has to solve personally. It is evident that the experience of
the single surgeon or of the Hospital is the main determinant of the
success of the repair, of a lower early mortality and of a lower
reoperation rate. As a consequence, MVr has to be considered a
subspecialty. However, this is not practically possible. There is no
agreement on the minimum caseload for surgeons or for Hospitals and is
difficult to identify any procedure able to identify who has to do what.
We, as surgeons, have to think that, anything we do, will influence the
length and the quality of life of our patients. Adopting new techniques
or new approaches has to be performed having in mind the patient’s
safety and the durability of the repair. Accepting a low-grade result in
the name of a lesser invasiveness is against the interests of the
patient and has to be rejected. Only an ethical vision of the profession
can guide our decisions.