Right ventricle-pulmonary artery coupling in repaired tetralogy of Fallot with pulmonary regurgitation: Clinical implications

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Right ventricle-pulmonary artery (RV-PA) coupling is a strong prognostic marker in several clinical settings, but few studies have focused on its role in repaired tetralogy of Fallot (rToF) with pulmonary regurgitation. To assess whether differences exist in RV-PA coupling, estimated by echocardiography, between patients with rToF and pulmonary regurgitation with or without an indication for pulmonary valve replacement (PVR). The study population included 40 patients with rToF, who were allocated to two groups: 20 with an indication for PVR (i-PVR group); and 20 without an indication for PVR (ni-PVR group). Forty healthy controls were also included. All subjects underwent echocardiography, and cardiac magnetic resonance (CMR) was available in 27/40 patients with rToF. RV-PA coupling was assessed by echocardiographic tricuspid annular plane systolic excursion/pulmonary arterial systolic pressure (TAPSE/PASP) and right ventricular stroke volume/right ventricular end-systolic volume (RVSV/RVESV) by CMR. TAPSE was similar in the i-PVR and ni-PVR groups (19.0±3.4 vs 18.8±2.7mm; P=0.97) whereas RV-PA coupling was significantly worse in the i-PVR group versus the ni-PVR group (TAPSE/PASP 0.8±0.3 vs 1.1±0.5mm/mmHg; P=0.001), and in the i-PVR group versus the control group (P=0.02); there was no difference between the ni-PVR and control groups (P=0.29). CMR data confirmed the echocardiography results, with a significant difference in RV-PA coupling between the i-PVR and ni-PVR groups (RVSV/RVESV 0.9±0.2 vs 1.2±0.3mL/min/mL; P=0.01). This study demonstrates worse RV-PA coupling, despite normal RV systolic function, in patients with rToF with an indication for PVR. RV-PA coupling could be a sensitive marker of a progressive maladaptive RV response to long-standing volume overload in rToF before the onset of clinical symptoms and RV systolic dysfunction.