Pulmonary to systemic flow ratio (Qp/Qs) is a hemodynamic parameter which is used to determine the significance of left-to-right shunts in congenital heart diseases. In patients with pulmonary hypertension (PH), Qp/Qs ratio decreases due to increased pulmonary artery pressures (PAP), and right ventricular dysfunction. In this study we aimed to investigate the prognostic value of Qp/Qs in predicting survival in PH patients without L-R shunt.
Material and method
In this prospective study of 116 consecutive PH patients without a left-to-right shunt, clinical and hemodynamic parameters were recorded at initial diagnosis. Baseline hemodynamic data including pulmonary artery pressures (PAP), pulmonary vascular resitance (PVR), cardiac index (CI), right atrial pressure (RAP) and Qp/Qs ratio were obtained. The prognostic values of baseline catheterization parameters were analyzed by Cox regression model.
In a mean follow-up of 36.months, 42 deaths occurred. On Cox regression analysis, among baseline hemodynamic parameters only Qp/Qs ratio (HR: 2.949 95% CI: 1.046- 8.333 p=0.04) and RAP ( HR: 1.091 95%CI: 1.042-1.142 p<0.001) significantly predicted mortality (Table 1). When the correlation between Qp/Qs and other well known prognostic variables were analyzed, BNP, 6 minute walking distance and TAPSE did not significanly correlate with Qp/Qs ratio. However baseline functional capacity (r:-0.236 p: 0.023), sPAPRHC (r:-0.229 p:0.025), and PVR (r: -0.270 p:0.008) were all negatively correlated with Qp/Qs ratio.
Decreased Qp/Qs ratio is associated with mortality in PH. Qp/Qs ratio may be a useful parameter in predicting severity of the disease and also survival in PH patients without left-to-right shunt.