Pulmonary artery (PA) compliance (PAC) is increasingly recognized as an independent predictor of mortality and morbidity in WHO group II Pulmonary Hypertension (PH) patients. PA pulse pressure (PAPP) in association with cardiac index (CI) can be a surrogate for PAC. Our study thus aimed to determine effect of pre-listing PAPP along with CI, on 6-month and 1-year heart transplant waitlist mortality.
All adults listed for heart transplantation from 1997-2016 were identified from United Network for Organ Sharing (UNOS) database. Predictors of mortality were identified using Cox proportional hazard models. As determined by receiving operator characteristics, CI 1.8 L/min/m2 and PAPP 22 mm Hg were considered optimal cutoffs and following four groups of patients were identified: Group 1: CI ≥ 1.8 L/min/m2 and PAPP < 22 mm Hg, Group 2: CI < 1.8 L/min/m2 and PAPP < 22 mm Hg, Group 3: CI ≥ 1.8 L/min/m2 and PAPP ³ 22 mm Hg, Group 4: CI < 1.8 L/min/m2 and PAPP ³ 22 mm Hg. Each group’s Kaplan-Meier curves (Figure 1) were then plotted for 6-month and 1-year survival.
After excluding status 1A and patients on left ventricular assist device (LVAD), 4768 patients with end stage heart failure (HF) were identified. On analysis, group 2 and 3, considered to have moderately decreased PAC, were observed to have decreased survival; with hazard ratio (HR) 1.32; CI- 1.22-1.83 and HR 1.51; CI-1.3-1.75 respectively. While group 4, with the least estimated PAC, had the worst survival with HR 1.71; CI-1.42, 2.07. Additionally, multivariate analysis revealed that PAPP was an independent predictor of mortality, HR 1.21; CI-1.07-1.38.
Our analysis thus demonstrates that in a large cohort of HF and WHO group II PH patients listed for heart transplant, PAPP along with CI is an independent predictor of 6-month and 1-year waitlist mortality.