Postrepair mitral valve gradient
A moderate positive correlation (r = 0.356, n = 391, P < 0.001) between the intraoperative and predischarge MV gradient was seen (Supplementary material, Figure S1). The haemodynamic results of valve repair are demonstrated in Table 3. As expected, postrepair MV gradients decreased with the size of annuloplasty ring implanted (Fig. 1). On linear regression analysis, increasing patient age (coefficient = −0.11, standard error = 0.005, P = 0.034) and annuloplasty ring size (coefficient = −0.181, standard error = 0.018, P < 0.001) were correlated with lower postrepair MV gradients (Table 4). On the other hand, increasing body surface area (coefficient = 0.905, standard error = 0.340, P = 0.008) and, interestingly, use of the Physio I ring (coefficient = 0.414, standard error = 0.122, P < 0.001) were correlated with higher postrepair MV gradients. The linear regression model demonstrated good fit with no evidence of heteroscedasticity or non-linearity (Supplementary material, Figure S2).
Figure 1:  Postrepair resting mitral valve gradients in relation to the implanted annuloplasty ring size. Smallest size rings (≤size 28) had the most pronounced effect on postrepair gradients. The middle horizontal line presents the median and the upper and lower borders of the box present the upper and lower quartiles. The upper and lower whiskers present the maximum and minimum values of non-outliers. Extra dots present the outliers.
Table 3:  Postoperative echocardiographic results
n = 484
Predischarge mitral valve gradient (mmHg)  3.46 ± 1.43
Predischarge heart rate (min−1)  80 ± 15
Predischarge stroke volume (ml)a  74 (58–93)
Predischarge cardiac index (l/m2)a  5.7 (4.6–7.4)
Predischarge haemoglobin value (mmol/l)  6.4 ± 0.8
Data are presented as means ± standard deviations and medians (IQR).
a  Available for ≥90% of patients.
IQR: interquartile range.
Table 4:  Univariable and multivariable linear regression analysis on risk factors associated with postrepair mitral valve gradients
Univariable analysis  Multivariable analysis
Coefficient  Standard error   P-value  Coefficient  Standard error   P-value
Gender (female)  0.114  0.137  0.40  0.069  0.153  0.65
Age (years)  0.000  0.006  0.98  −0.110  0.005  0.034
Body surface area  0.294  0.302  0.33  0.905  0.340  0.008
Atrial fibrillation  −0.137  0.136  0.32  −0.008  0.121  0.95
Posterior mitral annular plication  0.347  0.160  0.030  0.109  0.155  0.48
Annular decalcification  −0.682  0.223  0.002  −0.235  0.195  0.23
PMVL resection  0.028  0.139  0.84  0.188  0.126  0.14
PMVL indentation closure  −0.154  0.172  0.37  −0.123  0.149  0.41
Annuloplasty ring size  −0.164  0.017  <0.001  −0.181  0.018  <0.001
Annuloplasty ring type
 Physio I ring  0.486  0.129  <0.001  0.414  0.122  0.001
Postoperative blood haemoglobin value  −0.288  0.082  <0.001  −0.301  0.071  <0.001
Postoperative heart rate  0.029  0.004  <0.001  0.024  0.004  <0.001
PMVL: posterior mitral valve leaflet.