The resistance-compliance relationship at low pulmonary resistance: Integrating pulmonary wedge pressure into right ventricular load assessment

The inverse hyperbolic relationship between pulmonary vascular resistance (PVR) and pulmonary arterial compliance (PAC) is a well-established marker of right ventricular (RV) afterload. Pulmonary capillary wedge pressure (PCWP) is a known modifier of this relationship; however, its impact across pulmonary hypertension (PH) subgroups has not been well characterized. How does PCWP influence the resistance-compliance (RC) relationship in PH subgroups, and can it be integrated into PAC calculations? Data from routine right heart catheterizations were analyzed to evaluate the PVR-PAC relationship across PH subgroups, both with and without PCWP adjustment. The inverse PVR-PAC relationship was apparent in cohorts with low PVR (p < 0.001). In isolated post-capillary PH (Ipc-PH), this relationship was PCWP-dependent (unadjusted: p = 0.084; adjusted: p = 0.008). Incorporating PCWP significantly improved model fit (R² from 0.725 to 0.919). The RC relationship is broadly preserved across PH but is modulated by PCWP in low PVR states, particularly Ipc-PH. Adjusting PAC calculations for PCWP may enhance the clinical assessment of RV afterload using this metric.