Abstract 13077: Higher Occurrence of Right Ventricular Fibrosis in Right Ventricular Outflow Tract-dominant Than Diffuse Hypertrophic Types: A Pulmonary Hypertension Study Using Cardiac Computed Tomography

Abstract

Introduction: On cardiac CT of pulmonary hypertension (PH), two right ventricular (RV) hypertrophic (RVH) morphological types are seen, namely RV outflow tract-dominant and RV-diffuse. However, clinical significance of this difference is unclear. Hypothesis: These two morphological RVH types have different effects on myocardial characteristics, clinical severity and prognosis in PH patients. Methods: We retrospectively analyzed 43 PH patients (33 females, 55±15yrs, 31 chronic thromboembolic PH (CTEPH), 7 idiopathic pulmonary arterial (PA) hypertension). On CT, RV fibrosis was defined as contrast defects in early phase and abnormal enhancement in late phase. Cases were divided into 3 groups: RV outflow tract-dominant RVH (gp 1), RVH-diffuse (gp 2), and no RVH (gp 3). Mean follow up was 39.3±20.1, 58.3±17.7, 68.2±11.9 months, respectively. Results: There were 6, 26, 11 patients in gps 1, 2, 3, respectively. There were no significant differences in these percentages between CTEPH and idiopathic PA hypertension or between ages ≥60 and <60 yrs. There were no significant differences of R/S wave ratio on ECG V1 lead, maximum RV wall thickness on end-diastole (CT), plasma BNP and estimated PA systolic pressure (PASP) on TTE between gps 1 and 2. There were significant positive correlations between maximum RV wall thickness in end-diastole and plasma BNP in gp 1 (R=0.44) but no correlations in gp 2 (R=0.05). Similarly, there were significant positive correlations between maximum RV wall thickness in end-diastole and estimated PASP in gp 1 (R=0.38) but no correlations in gp 2 (R= -0.08). RV fibrosis was detected in 3 patients (50%) (gp1) and 1 patient (4%) (gp2) (P=0.003). Zero, 2, and 1 patients died due to PH during follow-up periods in gps 1, 2, 3 , respectively, and there were no significant differences in these percentages on Kaplan Meier analysis and log rank testing. Interobserver agreement between two observers was 91% in gp 1 and 77% in both gps 2 and 3. Conclusions: In PH patients, RV outflow tract-dominant RVH was relatively easy to diagnose and manifested with greater occurrence of RV fibrosis than diffuse-type. RV outflow tract-dominant RVH showed significant positive correlations of maximum RV wall thickness in end-diastole with plasma BNP and estimated PASP.