Right ventricular hemodynamics and performance in relation to perfusion during first year after heart transplantation

We aim to evaluate changes in invasive haemodynamics, right ventricular (RV) function, and perfusion during the first year after heart transplantation (HTx) and to determine the relation between RV function and myocardial perfusion.

Thirty patients were prospectively enrolled at the time of HTx. Right heart catheterization (RHC), comprehensive 2D and 3D echocardiography and cardiac biomarkers were performed at baseline (≤2 weeks after HTx) and at follow-up 1, 3, 6, and 12 months after HTx. At 12 months, HTx patients were subjected to an exercise stress test with assessment of maximal oxygen consumption (VO₂ max). RV myocardial perfusion reserve was evaluated by ¹⁵ O-H₂ O positron emission tomography at baseline and at 3 and 12 months after HTx. A group of 43 healthy subjects served as echocardiographic controls and a subgroup comprising 16 healthy controls underwent exercise stress test with simultaneous RHC. At baseline, HTx patients had higher pulmonary artery wedge pressure (PAWP) and right atrial pressure (RAP) and pulmonary vascular resistance (PVR) than healthy controls whereas cardiac index (CI) was reduced (PAWP; 14 mmHg [8;17] vs. 8 mmHg [7;10]; RAP: 7 mmHg [4;11] vs. 5 mmHg [4;6]; PVR: 1.9 wood units [1.3;2.6] vs. 1.1 wood units [1.0;1.4]; CI 2.4 L/min/m² [2.2;2.8] vs. 3.3 L/min/m² [2.8;.3.6], all P < 0.05). Normalization of filling pressures and CI was seen 3-6 months after HTx. During follow-up, RV function in terms of 3D ejection fraction (EF) and longitudinal strain (LS) improved in HTx patients but remained reduced compared with healthy controls at 12 months follow-up (3D RV EF: 52 ± 7% vs. 60 ± 8%; RV LS: 22 ± 4% vs. 28 ± 5%, both P < 0.001). During follow-up, RV perfusion reserve improved (baseline 2.1 ± 0.9; 3 months follow-up 3.2 ± 0.8; 12 months follow-up 3.7 ± 1.1, P < 0.0001). RV perfusion reserve significantly correlated to cardiac markers in terms of troponin T (r = -0.62, P < 0.0001), NT-proBNP (r = -0.65, P < 0.0001), RAP (r = -0.43, P < 0.01) and CI (r = 0.37, P < 0.01) and with VO₂ max 12 months after HTx (r = 0.75, P < 0.01).

Normalization of left and right atrial filling pressures is demonstrated within the first 3 to 6 months after HTx. RV function and RV perfusion reserve correlated and gradually improved during the first year after HTx but RV function remained reduced in HTx patients compared with healthy controls.