Does pulmonary artery pulsatility index predict mortality in pulmonary arterial hypertension?

Pulmonary artery pulsatility index (PAPi), defined as [(pulmonary artery systolic pressure - diastolic pulmonary artery pressure)/mean right atrial pressure], is a novel haemodynamic index that predicts right ventricular failure after myocardial infarction and left ventricular assist device implantation. We analysed if a low PAPi is associated with death in our 14 - ​year pulmonary arterial hypertension (PAH) registry.

Consecutive patients with newly diagnosed PAH and complete haemodynamic data were prospectively enrolled into our standing registry between January 2003 and December 2016. PAPi was calculated from baseline invasive right heart catheterization data. A prognostic cut-off value was determined with a decision tree. Baseline characteristics of 'high' and 'low' PAPi groups based on this cut-off were compared, as well as odds of death and time-to-death.

One hundred and two patients were included. Mean age was 53 years, and 77% were women. Our multi-ethnic cohort was 64% Chinese, 23% Malay, and 10% Indian. The aetiologies were idiopathic (33%), connective tissue disease (31%), congenital heart disease (24%), and others (12%). The low PAPi group (<5.3) had a greater age (56 years vs. 49 years), lower pulmonary artery systolic pressure (71 mmHg vs. 85 mmHg), and higher mean right atrial pressure (14 mmHg vs. 6 mmHg). Mortality risk was higher in the low PAPi group (adjusted odds ratio: 2.98 and adjusted hazard ratio: 2.23). Mean right atrial pressure was the strongest predictor (hazard ratio 1.114, P = 0.009) when components of PAPi were analysed.

Pulmonary artery pulsatility index was found to be predictive of mortality in PAH and may be a valuable marker for risk stratification. Its prognostic strength may be driven by mean right atrial pressure.