PURPOSE: Pulmonary vascular capacitance (PC) defined as the ratio of stroke volume to pulmonary pulse pressure (SV/PP) has been recently shown as a strong predictor of mortality in idiopathic pulmonary arterial hypertension (IPAH). Since it reflects properties of the large and medium sized pulmonary vessels, we hypothesized that low PC would also a predictor of mortality in patients with scleroderma-associated PAH (SSC-PAH).
METHODS: We analyzed hemodynamic data from the initial right heart catheterization (RHC) of patients with IPAH and SSC-PAH. PAH was defined as mPAP >25 mmHg and PVR > 3 Woods units. Survival was determined by SSDI database. Statistical analysis used chi-square test and Wilcoxon rank sum tests to compare differences between both groups.
RESULTS: Data of 90 patients (58 IPAH and 32 SSC-PAH) were analyzed. Patients in the SSC-PAH group were significantly older (59±10 yrs vs. 45±15 yrs; p<0.001). RV systolic pressure, mean PAP, and PVR were significantly higher in the IPAH group. Mean PC was 1.01±0.65 in IPAH group and 1.40±0.81 in SSC-PAH group with a p-value=0.012. There was no significant difference in the two groups with regard to TPG, SV, CO, PCWP, and mean RAP. In the IPAH group 31% of patients died over a follow up period of 4.2±2.3 years while 40.6%of patients in the SSC-PAH group died over a period of 2.5±1.7 years (P-value=0.001).
CONCLUSION: Even though patients in the SSC-PAH group had lower mean PAP, PVR, RV systolic pressure and a higher pulmonary capacitance, they had a significantly shorter period of survival. PC was a strong predictor of mortality in patients with IPAH and SSC-PAH. Further studies comparing these groups are warranted.
CLINICAL IMPLICATIONS: Pulmonary capacitance can be used as a prognostic marker in SSC-PAH as it is in IPAH.Potential to be used as a marker in response to therapy.
DISCLOSURE: Hadi Skouri, No Financial Disclosure Information; No Product/Research Disclosure Information