title: Cardiac magnetic resonance imaging-derived pulmonary artery distensibility index correlates with pulmonary artery stiffness and predicts functional capacity in patients with pulmonary arterial hypertension.
abstract: BACKGROUND
  Increased stiffness of the pulmonary vascular bed is known to increase mortality in patients with pulmonary arterial hypertension (PAH); and pulmonary artery (PA) stiffness is also thought to be associated with exercise capacity. The purpose of the present study was to investigate whether cardiac magnetic resonance imaging (CMRI)-derived PA distensibility index correlates with PA stiffness estimated on right heart catheterization (RHC) and predicts functional capacity (FC) in patients with PAH.
  
  
  RESULTS
  Thirty-five consecutive PAH patients (23% male, mean age, 44 ± 13 years; 69% idiopathic) underwent CMRI, RHC, and 6-min walk test (6MWT). PA distensibility indices were derived from cross-sectional area change (%) in the transverse view, perpendicular to the axis of the main PA, on CMRI [(maximum area-minimum area)/minimum area during cardiac cycle]. Among the PA stiffness indices, pulmonary vascular resistance (PVR) and PA capacitance were calculated using hemodynamic dataset from RHC. CMRI-derived PA distensibility was inversely correlated with PVR (R²=0.34, P<0.001) and directly correlated with PA capacitance (R²=0.35, P<0.001), and the distance in the 6MWT (R²=0.61, P<0.001). Furthermore, PA distensibility <20% predicted poor FC (<400m in 6MWT) with a sensitivity of 82% and a specificity of 94%.
  
  
  CONCLUSIONS
  Non-invasive CMRI-derived PA distensibility index correlates with PA stiffness and can predict FC in patients with PAH.
authors.affiliation: Division of Cardiology, Yonsei University College of Medicine, Yonsei University Health System, Seoul, Korea.
authors.forename: Ki-Woon
authors.initials: KW
authors.lastname: Kang
authors.forename: Hyuk-Jae
authors.initials: HJ
authors.lastname: Chang
authors.forename: Young-Jin
authors.initials: YJ
authors.lastname: Kim
authors.forename: Byoung-Wook
authors.initials: BW
authors.lastname: Choi
authors.forename: Hye Sun
authors.initials: HS
authors.lastname: Lee
authors.forename: Woo-In
authors.initials: WI
authors.lastname: Yang
authors.forename: Chi-Young
authors.initials: CY
authors.lastname: Shim
authors.forename: Jongwon
authors.initials: J
authors.lastname: Ha
authors.forename: Namsik
authors.initials: N
authors.lastname: Chung
mesh_terms: D000328:Adult; D006328:Cardiac Catheterization; D065627:Familial Primary Pulmonary Hypertension; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D011859:Radiography; D014655:Vascular Resistance