An Integrative Analysis of Echocardiographic and Haemodynamic Parameters in Heart Transplant Candidates: Specific Focus on Pulmonary Regurgitation Jet-Derived Mean Pulmonary Artery Pressure and Pulmonary Vascular Resistance.

Background and aim: Precise haemodynamic assessment is critical in heart transplant candidates with advanced left heart failure. While right heart catheterisation (RHC) is the gold standard for evaluating pulmonary haemodynamics, its invasive nature necessitates non-invasive alternatives. Transthoracic echocardiography provides a non-invasive approach to estimate haemodynamic parameters. This study focused on pulmonary regurgitation (PR) jet-derived mean pulmonary artery pressure (mPAP) and Doppler-based pulmonary vascular resistance (PVR), evaluating their correlation and agreement with RHC-derived measurements in this high-risk population.

Method: This prospective, single-centre study included 51 heart transplant candidates with a median ejection fraction of 15% (interquartile range, 13-20). PR jet-derived mPAP was calculated using the formula mPAP=4(PR peak velocity)²+right atrial pressure, and Doppler-based PVR as tricuspid regurgitation peak velocity/time-velocity integral (right ventricular outflow tract)×10+0.16. Correlation and agreement were assessed using Pearson correlation coefficients and Bland-Altman analysis. Subgroup and covariance analyses were performed, and receiver operating characteristic curves determined diagnostic performance.

Results: PR jet-derived mPAP correlated strongly with RHC (r=0.701; p<0.001), with a mean bias of -1 mmHg and limits of agreement from -14.6 to 12.6 mmHg. Echocardiographic PVR showed moderate correlation (r=0.681; p<0.001) and a mean bias of +0.88 Wood units. Subgroup analysis showed better agreement in patients with dilated cardiomyopathy and New York Heart Association class II, while tricuspid coaptation defects were associated with the lowest PVR correlation (r=0.368). Covariance analysis identified time-velocity integral (right ventricular outflow tract) as the strongest predictor of PVR. Receiver operating characteristic analysis identified optimal cut-offs of ≥26 mmHg for mPAP (area under the curve [AUC]=0.939) and ≥3.99 Wood units for PVR (AUC=0.910).

Conclusions: PR jet-derived mPAP showed good agreement with RHC, while Doppler-based PVR estimations demonstrated moderate correlation. These findings support transthoracic echocardiography as a complementary tool for pulmonary haemodynamic assessment, while emphasising the need for RHC for precise measurements.