Discussion
Variations in mitral valve surgery outcomes by geographic area and
institution has been emphasized in multiple
reports10-12. In this analysis, the outcomes of mitral
valve surgery within the same institution were different according to
the experience of the operator surgeon. Experienced surgeons were more
likely to attempt repair, used different operative techniques and had
higher repair rates. While surgeon experience was not an independent
risk factor for post-repair MR recurrence, it was an independent risk
factor for mortality (HR=2.66) irrespective of valve repair/replacement
and the pre-operative characteristics of the patients.
As in the New York state data, we identified higher rates of both CHF
and urgent/emergent surgery with less experienced surgeons. This
suggests a possible trend in referrals where higher risk patients tend
to be operated on by less experienced surgeons, who may be less inclined
to perform MV repair under unfavorable conditions8.
Interestingly, the number of techniques used in the repair was not
different between experienced and less experienced surgeons, but the
management of the anterior leaflet using neochordae — a complex
technique requiring a high level of experience — resulted in higher
repair rates in the experienced group. Leaflet resection and
annuloplasty rates were similar between both cohorts and also similar to
the national average, but artificial neochordae rates differed. In the
national study, 22.7% of mitral valve repairs had artificial cord
implantation, compared to 41.5% of repairs with experienced surgeons
and 18.7% with less experienced surgeons in this
analysis13.
This analysis also addresses the effects of calcification on the mitral
valve surgery outcomes. Extensive calcification extending to the
leaflets was the most common reason for replacement, and mitral annular
calcification (MAC) was the only independent risk factor for MR
recurrence. MAC was reported in ~ 20% of patients
undergoing mitral valve surgery14 and was an
independent risk factor for valve replacement15. The
extent of leaflet prolapse was not a risk factor for recurrence in this
cohort, as opposed to previous literature where anterior leaflet and
bi-leaflet involvement were associated with increased risk of
recurrence16-18. Of note, these studies included
patients who had surgeries decades ago, when the techniques of anterior
leaflet repair were not well-established and adopted.
The recurrence rate over the study period in this cohort was 13%, of
which 65% happened in the first year, which matches the existing
literature16. The most common causes for recurrence
were ring dehiscence and new lesions, which, at 36% each, largely
matches previous studies19, 20. Surgeon experience was
not a risk factor for MR recurrence after repair in this cohort as
opposed to previous reports. This could be explained by the fact that
less experienced surgeons were more likely to repair posterior leaflet
prolapse and replace anterior and bi-leaflet prolapses.
Finally, patients operated on by experienced surgeons had better
adjusted survival. This finding can’t be explained by the
repair/replacement rate or the preoperative characteristics of the
patients as it was shown to be an independent factor in the Cox hazard
model. This was reported on a larger scale in the NY state data and
requires further research8.