Haemodynamically Derived Pulmonary Artery Pulsatility Index Predicts Mortality in Pulmonary Arterial Hypertension

Background Pulmonary artery (PA) pulsitility index (PAPi) is a novel haemodynamic index shown to predict right ventricular failure in acute inferior myocardial infarction and post left ventricular assist device surgery. We hypothesised that PAPi calculated as [PA systolic pressure - PA diastolic pressure]/right atrial pressure (RAP) would be associated with mortality in the National Institutes of Health Registry for Primary Pulmonary Hypertension (NIH-RPPH). Methods The impact of PAPi, the Pulmonary Hypertension Connection (PHC) risk score, right ventricular stroke work, pulmonary artery capacitance (PAC), other haemodynamic indices, and demographic characteristics was evaluated in 272 NIH-RPPH patients using multivariable Cox proportional hazards (CPH) regression and receiver operating characteristic (ROC) analysis. Results In the 272 patients (median age 37.7 +/- 15.9 years, 63% female), the median PAPi was 5.8 (IQR 3.7-9.2). During 5 years of follow-up, 51.8% of the patients died. Survival was markedly lower (32.8% during the first 3 years) in PAPi quartile 1 compared with the remaining patients (58.5% over 3 years in quartiles 2-4; p < 0.0001). The best multivariable CPH survival model included PAPi, the PHC-Risk score, PAC, and body mass index (BMI). In this model, the adjusted hazard ratio for death with increasing PAPi was 0.946 (95% CI 0.905-0.989). The independent ROC areas for 5-year survival based on bivariable logistic regression for PAPi, BMI, PHC Risk, and PAC were 0.63, 0.62, 0.64, and 0.65, respectively (p < 0.01). The ROC area for 5-year survival for the multivariable logistic model with all four covariates was 0.77 (p < 0.0001). Conclusions Pulmonary artery pulsatility index was independently associated with survival in PAH, highlighting the utility of PAPi in combination with other key measures for risk stratification in this population.