OBJECTIVETo investigate the value of intravascular ultrasound (IVUS) on assessing pulmonary vascular properties (PVPs) and its relationship with hemodynamics, and mortality rate in patients with pulmonary arterial hypertension associated with connective tissue disease (PAH-CTD).

METHODSPatients (n=51) with highly suspected PAH-CTD were prospectively enrolled in our department between July 2011 and March 2014. All patients underwent right heart catheterization (RHC) and IVUS, and were divided into 3 groups: PAH-CTD (n=25), PAH due to other reasons (n=15), and non-PAH control group (n=11). Based on IVUS, PAH patients were divided into distal (n=22) and proximal (n=18) remodeling subtypes.A total of 408 pulmonary segments were detected by IVUS, and all patients were followed up to (19 ± 10) months.

RESULTSIVUS evidenced higher mean wall thickness (MWT) ((0.30 ± 0.02) mm and (0.33 ± 0.02) mm vs. (0.21 ± 0.02) mm) and percentage of MWT (WTP) ((13.62 ± 0.59)% and (14.39 ± 0.77)% vs. (9.57 ± 0.97)%) values in PAH patients compared to control patients (all P<0.01). Pulmonary vascular mechanical properties (PVMPs) including compliance ((8.85 ± 0.82) × 10(-2)mm(2)/mmHg(1 mmHg=0.133 kPa) and (6.28 ± 0.65) × 10(-2)mm(2)/mmHg vs. (41.59 ± 5.02) × 10(-2) mm(2)/mmHg, all P<0.01), distensibility ((0.83 ± 0.09)%/mmHg and (0.55 ± 0.06)%/mmHg vs. (3.16 ± 0.38) %/mmHg, all P<0.01), elastic modulus ((169.25 ± 15.10) mmHg and (253.00 ± 22.11) mmHg vs.(43.78 ± 4.27) mmHg, all P<0.01) and stiffness index β (4.19 ± 0.41 and 5.18 ± 0.34 vs. 2.39 ± 0.27, P<0.05 or 0.01) in PAH groups were all significantly worse than in control group (all P<0.01). An inverse exponential association was found between PVMPs and hemodynamics with R(2) ranging from 0.544 to 0.777 (P<0.001). PVMPs tended to be better in group PAH-CTD than in PAH group due to other reasons.Mortality rate was similar between the two PAH groups, while PAH with distal remodeling subtype was linked with significantly higher mortality rate than PAH with the proximal remodeling subtype (23 % vs. 0, HR=10.14, P<0.05).

CONCLUSIONSIVUS plays an important role in the assessment of PAH-CTD patients in terms of evaluating PVPs and predicting mortality rate. PAH patients have deteriorated PVPs, but PVMPs tended to be better in PAH-CTD than in PAH patients due to other reasons. The mortality rate was similar between PAH groups, while PAH patients with the distal remodeling subtype is linked with a higher mortality rate than PAH patients with the proximal remodeling subtype.