Impact of Patient Positioning on Hemodynamic Assessment: A Comparison of Supine and Upright Right Heart Catheterization in Pulmonary Hypertension and HFpEF

BackgroundRight heart catheterization (RHC) is the gold standard for the objective diagnosis of heart failure with preserved ejection fraction (HFpEF) and pulmonary hypertension (PH). Typically performed in the supine position, RHC may not accurately reflect the hemodynamic changes that occur during upright activity. The effect of patient positioning on RHC measurements, especially in distinguishing between precapillary and postcapillary PH, has been underexplored. This study aims to compare hemodynamic measurements between supine and upright RHC and assess how patient positioning influences the diagnosis of PH. MethodsWe performed a retrospective observational study of patients who underwent both supine and upright RHC during invasive cardiopulmonary exercise testing (iCPET) at Brigham and Womens Hospital between January 2015 and January 2024. Hemodynamic parameters were measured and compared between both positions. ResultsCompared to upright RHC, supine RHC showed consistently higher mean PAP (21 {+/-} 8.5 mmHg vs. 16 {+/-} 8 mmHg) and PCWP (12 {+/-} 4.7 mmHg vs. 6.4 {+/-} 4.9 mmHg). Supine RHC diagnosed significantly more cases of HFpEF (21.8% vs. 5.7%) and isolated postcapillary PH (10.9% vs. %), primarily due to overestimation of PCWP. Upright RHC had a higher specificity for detecting elevated PCWP (>15 mmHg) in patients with elevated NT-proBNP (92.8% vs. 74.3%), iCPET diagnosed exercise HFpEF (95.29% vs 80.92%), PCWP/CO>2 (98.27% vs 84.61%) and demonstrated stronger association with PCWP/CO>2 (OR 9.11, 95% CI 5-16) compared to supine RHC. The differences in mPAP and PCWP measurement between supine and upright RHC persisted regardless of sex, age, BMI, or severity of chronic lung disease. ConclusionsHemodynamic discrepancies between supine and upright RHC exist which can significantly affect the diagnosis of PH and HFpEF. Upright RHC provides more physiologically relevant data, potentially enhancing diagnostic accuracy and should be considered in the evaluation of patients with PH. Clinical PerspectiveO_ST_ABSWhat is new?C_ST_ABSO_LIThis study highlights significant differences in hemodynamic measurements of mean pulmonary artery pressure and pulmonary capillary wedge pressure between supine and upright RHC. C_LIO_LIThe difference in supine and upright hemodynamics persists despite age, sex, BMI, FEV1 or smoking. C_LIO_LICompared to upright RHC, supine RHC results in overestimation of PCWP resulting in misclassification of PH. C_LI What are the clinical implications?O_LIUtilizing upright RHC may enhance the accuracy of diagnosing PH and HFpEF, leading to better-targeted therapies and management strategies for patients. C_LIO_LIImproved diagnostic precision could reduce unnecessary treatments and hospitalizations associated with misdiagnosed heart failure and pulmonary hypertension. C_LI