Comment
This was a single-center, retrospective report of the early and
long-term results of consecutive cases of mitral valve surgery for
secondary mitral valve regurgitation with poor left ventricular
function.
The early results of this study were good in terms of surgical mortality
and morbidity. Our operative strategy was devised to reduce aortic
cross-clamp time in poor left ventricular function. Concomitant coronary
bypass was performed in on-pump beating fashion as much as possible, and
mitral valve replacement was chosen for critically ill
patients.10 With these modifications, more patients
could tolerate open heart surgery than we expected even with reduced
cardiac function.
Since the results seem to imply that poor left ventricular function
itself might not be a contraindication for open cardiac surgery,
operative indications should be considered very carefully. In the
present study, 26 cases (37.7%) had LVEF ≤20%, but no patient had LVEF
<10%. Preoperative mean left ventricular diameter was not
extremely large, being 65.1/58.6 mm in diastole/systole. The cases with
extremely dilated or more reduced cardiac function may not be able to
tolerate open heart mitral valve surgery. For such patients, a left
ventricular assist device or heart transplantation may be indicated.
Since surgical stress or trauma is much greater than that of a catheter
procedure, we should carefully choose which modality to use to restore
secondary mitral regurgitation with poor left ventricular function,
especially in very ill patients. For critical patients with poor left
ventricular function, percutaneous treatment might be a better option
even if it is less effective than surgical treatment1.
Although there was no postoperative
mortality, and the morbidity rate was low, except for paroxysmal atrial
fibrillation, postoperative hospitalization was long, more than 3 weeks.
This is probably because patients with poor cardiac function have a slow
recovery and require a longer time to optimize their medication regimens
that include angiotensin-converting enzyme inhibitors, angiotensin
receptor/neprilysin inhibitors, mineralocorticoid receptor antagonists,
beta-blockers, or sodium-glucose co-transporter 2
inhibitors15.
Long-term survival in the present study was acceptable compared to the
previous reports, in which the long-term results for secondary mitral
valve regurgitation were dismal when only pharmacotherapy was
provided.16,17 However, re-admission-free rates were
low, 61.6% at 3 years and 55.3% at 5 years. This may imply that poor
left ventricular function remains even after open mitral valve surgery
with good control of mitral regurgitation. Multidisciplinary therapy
should be provided to these subsets, including pharmacotherapy, diet,
rehabilitation, and cardiac resynchronization therapy, even after the
surgery.
Concerning risk factors for long-term survival, the clinical frailty
scale score was the only predictor of long-term mortality in the present
study. Th clinical frailty scale is a simple method to
semi-quantitatively assess patient frailty.18 It has
been reported that it can predict late mortality in certain
cases.19,20 Since the present study showed worse
long-term survival in patients with high clinical frailty scale scores,
the operative indications need to be considered carefully in such ill
patients, because surgical stress or trauma could make the patients’
frailty worse. For patients with a high clinical frailty scale score,
percutaneous transcatheter mitral valve edge-to-edge repair might be a
better option, because it is far less invasive than open heart surgery.
The present study had several limitations. First was the retrospective
design of the study. Once we selected open heart surgery for the
patients, huge selection bias existed.
Second, the number of patients was small, and data in the present study
represent our clinical experience with a consecutive series of surgical
correction for mitral regurgitation with poor left ventricular function.
However, the present results reflect real-world clinical practice and
imply that open heart surgery could be appropriate for selected patients
even with poor left ventricular function.
The last limitation was that, because of the retrospective nature of the
investigation, this study did not have a control group. Whether surgical
correction of secondary mitral regurgitation provides greater benefit
than other therapeutic options over the long-term is unknown. However,
considering that several articles have reported a poor prognosis for
patients with secondary mitral regurgitation and our good operative
results, we feel encouraged to provide open mitral valve surgery if the
patient can tolerate the surgery.