Results
Between 2011 and 2016, 576 patients underwent mitral valve surgery for
severe MR due to degenerative valve disease. Majority or 77.2% of the
operations (n= 444) were performed by 3 experienced surgeons, and 6
surgeons with less experience performed 22.8 % of the operations
(n=132). No patient left the OR with an unsatisfactory repair (moderate
or higher MR on post-pump ECHO). Patients operated on by less
experienced surgeons were more likely to be non-Caucasian, to have
higher body mass index, chronic lung disease, CHF, lower ejection
fraction, and to be undergoing an urgent or emergent operation. Other
characteristics, including age, sex, smoking status, other comorbidities
including DM, hypertension, dyslipidemia, dialysis, peripheral vascular
disease, cerebrovascular disease, and previous myocardial infarction,
New York Heart Association (NYHA) class and atrial fibrillation were not
different between the two groups (Table 1).
Procedural details by surgeon experience are presented in Table 2.
Experienced surgeons were more likely to attempt repair (P=0.024) and
more likely to succeed in repair (P=0.001). Experienced surgeons were
more likely to attempt repair of both anterior leaflet prolapse and
bi-leaflet prolapse (P=0.005). There was no difference in attempted
repair of posterior leaflet prolapse (P=0.871). Fewer patients had
residual MR in the experienced group (P=0.03). Experienced surgeons had
shorter mean cross clamp times (P<0.001). Less experienced
surgeons used the trans-septal approach more often (P<0.001)
and were more likely to describe leaflet restriction
(P<0.001). Valve pathology represented by leaflets affected,
calcification, and annular dilatation were not statistically different
between both groups.
The technical score (number of techniques used in the repair) was not
different between both groups, but the techniques used differed
according to surgeon experience. Experienced surgeons were more likely
to use neochordae (P<0.001), and less experienced surgeons
used chordae transfer more often (P<0.001). Rates for other
techniques were not significantly different between the two groups.
(Table 3).
Repair rate was higher in the experienced group (81.3% vs 69.7%,
P=0.005), and rationale for valve replacement differed by surgeon
experience (P=0.001). Extensive calcification was the primary reason for
replacement in the experienced group, whereas failure of attempted
repair was the most common in the less experienced group (Table 4).
The overall rate of recurrence was 13% (n=61) over the study period.
Most (69%) recurrences happened in the first 2 years after surgery
(Figure 1). On multivariable logistic regression analysis; in the first
two post-operative years, surgeon experience was not a risk factor for
recurrence. Annular calcification was the only independent factor for
higher risk of recurrence (OR = 8.98 CI 3.19-25.28). Patient’s age, male
sex, DM, hypertension, urgent/emergent surgery and anterior/bi-leaflet
prolapse were not independent risk factors for recurrence (Figure 2). Of
the patients with recurrent MR, 23% (n=14) underwent mitral
reoperation, and the other 77% (n=38) were either asymptomatic or high
risk for reoperation. Reasons for recurrence according to surgeon
description in the operative reports included dehisced ring in 35.7%
(n=5), new lesions in 35.7% (n=5), endocarditis in 14.3% (n=2), and
torn neochordae in 14.3% (n=2). Of the patients who underwent
reoperation, re-repair was performed in 35.7% (n=5), all of which were
performed by experienced surgeons, and the remainder underwent valve
replacement.
The overall mortality (throughout 2011-2020) was 11.1% (n=64), with a
rate of 8% (n=37) in the experienced group and 21% (n=27) in the less
experienced group. By KM method, adjusted survival was higher in
patients treated by more experienced surgeons (log rank
P<0.0001) (Figure 3). 5-years survival in the patients
operated on by experienced surgeons was 93.9% (n=417) and 80.2%
(n=105) in the patients operated on by less experienced surgeons.
Independent risk factors for mortality on Cox model were: less
experienced surgeon (HR= 2.64, P=0.002), age (HR=1.03, P=0.012), valve
replacement (HR=1.75, P=0.04), CHF (HR=2.01, P=0.029) and chronic lung
disease (HR=2.25, P=0.005) . DM, dyslipidemia, HTN, Afib and
urgent/emergent surgery were not independent factors for mortality
(Table 5).