Pulmonary Artery Pulsatility Index (PAPi)

The Pulmonary Artery Pulsatility Index (PAPi) is an invasive hemodynamic measure used to assess right ventricular (RV) function and predict adverse cardiovascular outcomes. PAPi is calculated as pulmonary artery pulse pressure divided by right atrial pressure and reflects RV contractility, RV preload, and RV afterload. Initially developed to identify severe RV dysfunction in acute inferior myocardial infarction, PAPi has since been validated in cardiogenic shock, advanced heart failure, and evaluation for mechanical circulatory support. Lower PAPi values are associated with increased risk of RV failure, need for right ventricular mechanical support, and mortality. PAPi should be interpreted in clinical context, as optimal thresholds may vary across patient populations.