RESULTS
General clinical characteristics
According to the estimated PAWP, forty-one patients had pre-capillary
PH, and fifty-seven patients had post-capillary PH. Clinical
characteristics of the patients were detailed in Table 1 . In
line with the NICE classification[1], most of patients with
pre-capillary PH belonged to group 1, 3, and 4, while patients with
post-capillary PH could be predominantly classified into group 2. There
were significantly higher with NT-Pro BNP, hemoglobin and HbA1c in
post-capillary PH group comparing with pre-capillary PH group
(p <0.05). However, BMI, BSA, heart rate, systemic blood
pressure and serum Hb did not differ between the two groups
(p >0.05).
Echocardiographic analysis (Table 2 )
Although the diameter of pulmonary artery (PA) and the areas of right
atrial (RA) were enlarged in both groups, there were no significantly
differences in structure and function of the right heart chamber between
the two groups, including PA, RA areas, RVFAC, S’, TAPSE and TAPSE/PASP
(p >0.05). For the left ventricular, the LVEDI,
LVESI, LVMI and E/e’ were obvious higher in patients with post-capillary
PH, while the LVEF was lower than pre-capillary PH
(p <0.001).
LA volume indices were significantly increased in post-capillary PH
compared to pre-capillary PH (LAVImax: 54.89±22.04 vs. 29.54±13.06
mL/m2, LAVImin: 36.75±17.65 vs. 16.26±8.57
mL/m2, LAVIpreA: 46.55±20.49 vs. 23.25±11.48
mL/m2, p < 0.0001), while DEI
(0.34±0.12 vs. 0.45±0.11, P < 0.001), PEI (0.15±0.10
vs. 0.22±0.11, P = 0.0001) and AEI (0.21±0.11 vs. 0.30±0.12,P = 0.05) were decreased (Figure 2) . LASr (11.30±6.92 %
vs. 17.50±6.70 %, P < 0.001) and LAScd (-6.45±3.75 %
vs. -11.38±5.78 %, P < 0.001) obviously reduced in
post-capillary PH group compared with pre-capillary PH group. Besides,
there were obvious decreased with LA strain in patients of
post-capillary PH, as a result, the post-capillary PH group had higher
ePALGS. (Figure 3 )
Regression analysis
Logistic regression analysis was used to determine which of the
parameters of echocardiography could be used to distinguish pre- from
post-capillary PH. The parameters would be put into multivariate
analysis if p <0.10 in univariate analysis. Thus, the
volume and the function of LA in different phases, LASr, LAScd, LVEDi
and LVEF were chosen as inputs for multivariate logistic regression
model. However, only LAVImax (OR: 1.40; 95% CI, 1.05–1.87; P =
0.021) and LAScd (OR: 1.76; 95% CI, 1.18–2.49; P = 0.004) were
considered as the most powerful independent predictors for detecting
post-capillary PH (Table 3 ). ROC analysis showed that LAVImax
(AUC=0.82, p < 0.001) and LAScd (AUC=0.78, p<0.001) had a high discriminating power in distinguishing
between pre-capillary and post-capillary PH groups, and their cutoff
values were 35.69ml/m2 (sensitivity 86%, specificity74%) and -9%
(sensitivity 80%, specificity70%) (Figure 4A ). Considering
LAVImin and ePLAGS were useful to discriminate between pre- and
post-capillary PH in previous studies, both the parameters were also
taken into ROC analysis in our studies. It was demonstrated that they
had high differentiation capability (LAVImin: AUC=0.84, p<0.001; ePLAGS: AUC=0.72, p <0.001) as well
(Figure 4B ).
Observer variability
Intra-observer variability for LAVImax, LAVImin, LAVIpreA, LASr, LAScd
and LASct by inter-class correlation were 0.992 (p <
0.001), 0.983 (p < 0.001), 0.994 (p <
0.001) and 0.960 (p < 0.001), 0.901 (p< 0.001),0.878 (p = 0.001) respectively. Inter-observer
variability for LAVImax, LAVImin, LAVIpreA, LASr, LAScd and LASct by
inter-class correlation were 0.985
(p < 0.001),
0.991 (p < 0.001), 0.935 (p < 0.001)
and 0.963 (p = 0.001), 0.848 (p = 0.001); 0.802 (p= 0.001) respectively.