sPAP/PAAT Ratio as a New Index of Pulmonary Vascular Load: A Study in Normal Subjects and Ssc Patients with and without PH

In pulmonary hypertension (PH), the development of right ventricular (RV) dilatation and RV failure are signs of accelerated progression of the disease, resulting in an increased risk of cardiac death. Even the noninvasive assessment of systolic blood pressure in the pulmonary artery undertaken by echocardiography does not provide a measure of ventricle-pulmonary interaction. Some studies have shown the potential for echocardiography to indirectly evaluate pulmonary vascular resistance (PVR) and the acceleration time of pulmonary outflow (PAAT). We used systolic pulmonary artery pressure (sPAP) and pulmonary vascular resistance to develop an sPAP/PAAT ratio (strength/surface unit)/(time) for this study. From January 2017 to December 2018, 60 healthy subjects and 63 patients with systemic scleroderma (Ssc) (60 females, 3 males), 27 with PH and 36 without PH at two-dimensional echocardiographic/Doppler, were screened. In normal subjects, the mean sPAP/PAAT ratio was 0.26 ± 0.063, which indicated optimal pulmonary arterial ventricle coupling and biventricular function. The data derived from the analysis of the Ssc patients showed that those presenting pre-capillary PH at cardiac catheterization had an sPAP/PAAT ratio of 0.40 ± 0.05. There was a significant correlation between sPAP/PAAT with Walk Distance (WD) and PVR, but not with TAPSE. Interobserver variability was less than 5%. The sPAP/PAAT ratio is a new parameter that may indicate pulmonary vascular afterload and interaction, both in normal subjects and in patients with Ssc and PH.