Impact of patient positioning on hemodynamic assessment: A comparison of supine and upright right heart catheterization.

The impact of patient positioning on PCWP measurement and PH classification is underexplored. This study evaluates the differences in hemodynamic assessments between supine and upright RHC. We conducted a retrospective analysis of a single-center iCPET registry, comparing sequential hemodynamic measurements in the supine and upright positions in 1307 patients. Compared 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). The differences in mPAP and PCWP measurements between supine and upright RHC persisted regardless of sex, age, BMI, or severity of chronic lung disease. Supine RHC diagnosed significantly more cases of HFpEF (21.8% vs. 5.7%) and isolated postcapillary PH (10.9% vs. 1.8%), primarily due to the overestimation of PCWP. Upright RHC had a higher specificity for detecting elevated PCWP (>15 mmHg) in patients with PCWP/CO>2 (98.27% vs. 84.61%) and demonstrated a stronger association with PCWP/CO>2 (OR 9.11, 95% CI 5-16) compared to supine RHC (p = 0.058). PCWP measured in the supine position is higher compared to upright assessment and probably results in increased diagnosis of postcapillary PH.