Echocardiographic Assessment of RV–PA Coupling in Advanced Heart Failure: A Comparative Analysis of Volumetric and Strain‐Based Measures

BACKGROUND: Right ventricular (RV) dysfunction is a key determinant of prognosis in advanced heart failure (HF) patients, particularly those undergoing heart transplantation. Noninvasive RV-pulmonary arterial (PA) coupling indices, such as tricuspid annular plane systolic excursion (TAPSE)/pulmonary artery systolic pressure (PASP), fractional area change (FAC)/PASP and strain-based parameters, offer potential in predicting clinical outcomes. However, their comparative prognostic value remains unclear. METHODS: A retrospective cohort of 247 patients evaluated for heart transplantation between 2021 and 2023 was included. Echocardiographic parameters, including TAPSE (mm), FAC (%), RV ejection fraction (RVEF, %), lateral tricuspid annular systolic velocity (s' by tissue Doppler imaging, cm/s), RV free-wall strain (RVFWS, %), and global longitudinal strain (RVGLS, %) and PASP (mmHg), were measured. The primary composite outcome was heart transplantation, LV assist device implantation, or all-cause mortality. Cox regression (hazard ratios per 1-standard deviation [SD] change; for strain, per 1-SD decrease in absolute magnitude) and time-dependent receiver operating characteristic (ROC) analyses were performed to assess the prognostic value of RV-PA coupling indices. RESULTS: During a median follow-up of 452 days, 62 patients (25.1%) experienced the primary outcome. Patients with adverse outcomes had significantly lower TAPSE, FAC, s' (TDI), and higher PASP. RV-PA coupling indices, including TAPSE/PASP, FAC/PASP, and RVGLS/PASP, were significantly lower in these patients. Among those parameters, RVEF/PASP and TAPSE/PASP showed numerically higher prognostic performance with C-index values of 0.827 and 0.826, respectively, while RV strain indices appeared to demonstrate relatively stronger prognostic capacity during longer follow-ups. CONCLUSION: Noninvasive RV-PA coupling indices, particularly TAPSE/PASP, FAC/PASP, and RVEF/PASP, were associated with adverse outcomes in advanced HF patients and may provide useful information for early risk stratification. Strain-based indices, especially RVFWS/PASP, appeared to offer additional prognostic value during longer-term follow-up. These findings highlight the potential clinical relevance of RV-PA coupling; however, they should be regarded as descriptive and hypothesis-generating until validated in larger, prospective cohorts.