Calculation of pulmonary capillary wedge pressure including left atrial function is superior to morphology alone and accurately identifies elevated filling pressures in left heart disease

BACKGROUND: Right heart catheterization (RHC) with pulmonary capillary wedge pressure (PCWP) assessment is the reference standard for diagnosis of heart failure with preserved ejection fraction (HFpEF), but remains largely underused. Different approaches for non-invasive PCWP calculation have been proposed. However, as left atrial strain (LA Es) and end-systolic volume index (ESVi) emerge as key criteria in HFpEF, we sought to investigate them for PCWP calculation. METHODS: The derivation population consisted of patients referred to RHC and cardiovascular magnetic resonance (CMR) imaging who were enrolled in a prospective monocentric registry. Patients were classified by RHC according to current guideline recommendations. The external validation population consisted of patients included in the HFpEF-Stress trial who underwent exercise-stress RHC and CMR with follow-up after 4 years for hospitalized cardiovascular events. Performance of strain-derived PCWP was compared to a published LA volume (LAV) and left ventricular mass (LVM) derived method. RESULTS: The derivation population consisted of n = 209 patients, n = 123 underwent exercise-stress RHC (n = 55 without pulmonary hypertension PH, n = 72 pre-capillary, n = 27 combined post- and pre-capillary pulmonary hypertension CpcPH, n = 15 isolated post-capillary pulmonary hypertension IpcPH, n = 34 exercise, and n = 6 unclassified PH). Linear regression models identified the following formulae for functional PCWPrest 10.304 - 0.095 * Es + 0.098 * ESVi and functional PCWPstress 24.666 - 0.251 * Es + 0.056 * ESVi calculation. The validation population consisted of n = 74 patients (n = 15 without, n = 5 pre-capillary, n = 8 CpcPH, n = 10 IpcPH, and n = 32 exercise PH with n = 4 remaining unclassified). Functional PCWPrest (11.8) and RHC-derived PCWPrest (11 mmHg) were statistically similar (p = 0.285) and showed moderate correlation (r = 0.53, p < 0.001). Functional PCWPrest (area under the curve AUC 0.80) and PCWPstress (AUC 0.85) accurately identified HFpEF patients, were superior to LAV/LVM-based PCWP (AUC 0.67, p ≤ 0.002) and showed prognostic implications (hazard ratio 1.37 (1.16-1.62) and 1.29 (1.14-1.46), p < 0.001). CONCLUSION: Functional PCWP may aid in the identification of post-capillary involvement in PH and HFpEF superiorly compared to morphology-derived PCWP and shows prognostic implications.