Abstract

BACKGROUND: This study evaluated the utility of a novel index, pulmonary arterial (PA) proportional pulse pressure (PAPP; range 0-1, defined as [PA systolic pressure - PA diastolic pressure] / PA systolic pressure), in predicting mortality in patients with World Health Organization group 1 pulmonary hypertension (PH). HYPOTHESIS: Low PAPP is associated with increased 5-year mortality independent of a validated contemporary risk-prediction equation (Pulmonary Hypertension Connection [PHC] equation). METHODS: In a group of 262 patients in the National Institutes of Health Primary Pulmonary Hypertension (NIH-PPH) Registry, PAPP and the PHC risk equation were used to predict mortality during 5 years of follow-up using Cox proportional hazards models. Kaplan-Meier survival curves were used to compare mortality among PAPP quartiles, and significance was tested using the log-rank test. RESULTS: Patients in the lowest quartile (PAPP ≤0.47) had a significantly higher 5-year mortality than did patients in higher quartiles (log-rank P = 0.016). In a Cox model adjusted for the PHC equation, PAPP remained significantly associated with 5-year mortality (hazard ratio: 0.74 per 0.10 increase in PAPP, 95% confidence interval: 0.61-0.90). The χ² statistic for the single PAPP covariate in this model was 8.8 (P = 0.003), which compared favorably with the χ² statistic of 15.2 (P < 0.0001) for the multivariable PHC equation. CONCLUSIONS: PAPP, an index of ventricular-arterial coupling, is independently associated with survival in World Health Organization group 1 PH. The use of this easily measurable index for guiding risk stratification needs further investigation.