Right Ventricular Outflow Tract Velocity Time Integral Is the Strongest Echo-Doppler Predictor of Right Ventricular Fibrosis in Patients with Pulmonary Arterial Hypertension

Abstract

Purpose Right ventricular (RV) late gadolinium enhancement (LGE) is indicative of RV fibrosis and has correlated with pulmonary artery pressures (PAP), RV ejection fraction (RVEF) and outcomes in pulmonary hypertension patients. We evaluated whether echo-Doppler measures of RV structure, function, and hemodynamics were predictive of RV-LGE in patients with pulmonary arterial hypertension (PAH). Methods and Materials We reviewed our cardiac MRI (CMRI) and transthoracic echocardiography (TTE) databases to identify PAH patients who had TTE, CMRI and catheterization within 180 days. RV echo-Doppler quantitation was performed by a single reader blinded to patient LGE status. We compared TTE, CMRI and hemodynamic variables in RV-LGE+ and RV-LGE- groups. Results 26 PAH patients (56±16 yrs, 81% female) were included in this study. 15 (58%) had RV-LGE on CMRI. Invasive hemodynamics were similar in LGE- and LGE+ patients (mean PAP 40±21 vs. 43±12mmHg, P=0.32, RAP 11±9 vs. 7mmHg, P=0.27). RVEF (41±18% vs. 41±15%, P=0.89) and RVEDVI (103±52 vs. 101±50 ml/m2) on CMRI were also similar between groups. Echo-Doppler measures of RV geometry were similar in LGE+ and LGE- patients (RV/LV ratio 1.2±0.56 vs. 1.14±0.33, P=0.89). Echo-Doppler measures of RV function also did not predict LGE positivity (TAPSE 14±7 vs. 17±8mmHg, RVFAC 25±10% vs. 24±11%, P=0.59). Doppler hemodynamic variables were the only TTE measures that predicted LGE positivity: RV outflow tract (RVOT) velocity time integral (VTI) was higher in LGE- vs. LGE+ patients (15±5 vs. 12±2cm, P=0.02) and there were non-significant trends towards lower RVOT acceleration time (83±28 vs. 67±14ms, P=0.19) and higher estimated PAP (60±30 vs. 78±37mmHg, P=0.35) in LGE+ patients. Conclusions RVOT VTI was the strongest echo-Doppler predictor of RV fibrosis in this PAH cohort. Other standard echo-Doppler measures of RV structure and function were relatively poor in terms of predicting RV-LGE in patients with PAH.