From two pressures to three: reconstructing mean, systolic, and diastolic pulmonary arterial pressures in pulmonary hypertension

Background Mean pulmonary arterial pressure (mPAP) defines pulmonary hypertension (PH) and underpins hemodynamic classification. mPAP is time averaged during right heart catheterization. In echocardiographic studies, systolic and diastolic pressures (sPAP and dPAP) are frequently reported, and the conventional formula mPAP ≈ dPAP+0.33×pulse pressure (PP) is widely used, although its 0.33 form factor was not specifically calibrated for PH. The geometric formula mPAP ≈ √(sPAP×dPAP) has also been proposed. Whether these formulas and their rearrangements can accurately reconstruct a pressure component missing from a hemodynamic dataset when the other two are available remains uncertain. Methods This analysis included invasive hemodynamic data from 336 patients with idiopathic pulmonary arterial hypertension, post-capillary PH, and chronic thromboembolic PH. mPAP, sPAP, and dPAP were compared with values estimated using the conventional 0.33 formula, a cohort-derived recalibrated 0.37 formula based on the observed form factor, and the geometric formula. Results Measured mPAP was 41.2±10.3 mmHg. The 0.33 formula underestimated mPAP (mean bias −1.6±2.6 mmHg) and, when rearranged, overestimated sPAP (+4.8±7.8 mmHg) and dPAP (+2.4±3.9 mmHg). The 0.37 formula reduced all three mean biases to <1 mmHg while preserving precision. The geometric formula closely estimated measured mPAP (mean bias +0.1±3.0 mmHg). For both the 0.37 and geometric formulas, mPAP estimation performance was not materially altered by PH phenotype, age, sex, PP, heart rate, stroke volume, PA stiffness, or resistance. Conclusions In PH, form factor recalibration to 0.37 improved mPAP estimation and pressure-set consistency and may support missing-value estimation. The geometric relationship was confirmed and provides a parameter-free framework for physiological interpretation.