title: Prognostic value of acute vasodilator response in pulmonary arterial hypertension: beyond the "classic" responders.
abstract: BACKGROUND
  A "classic" response to acute vasodilator testing (drop of >10 mm Hg in mean pulmonary artery pressure [mPAP] to <40 mm Hg) confers an excellent prognosis in patients with idiopathic pulmonary arterial hypertension (IPAH) and identifies candidates for treatment with calcium channel blockers (CCB). Little is known about vasodilator responsiveness (VR) in other types of PAH, or about outcomes in patients with a significant but "non-classic" decrease in mPAP. We hypothesized that VR occurs in non-idiopathic PAH and non-classic VR portends a better prognosis than no VR in PAH.
  
  
  METHODS
  Acute VR testing with nitric oxide was performed on 155 consecutive patients referred for PH evaluation. Non-classic response was defined as decrease in mPAP >10 mm Hg to >40 mm Hg with preserved cardiac output. Demographics and functional status were assessed at baseline and the first clinic visit after VR testing, and survival was followed over time.
  
  
  RESULTS
  Twenty patients (13%) displayed classic VR. Among classic responders, 12 (60%) had IPAH and 8 (40%) had connective tissue disease-associated PAH (CTD-PAH); however, only responders with IPAH had improved survival compared with non-responders (p = 0.02). Thirteen patients (8%) had a non-classic VR. Non-classic response was not associated with improved survival compared with non-responders (p = 0.86). Acute change in mPAP or pulmonary vascular resistance in the entire cohort did not predict survival.
  
  
  CONCLUSIONS
  Classic acute VR occurs in CTD-PAH as well as IPAH; however, only IPAH patients have improved outcomes. A significant but non-classic VR is not associated with improved survival.
authors.affiliation: Department of Internal Medicine.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Halliday
authors.affiliation: Division of Allergy, Pulmonary, and Critical Care Medicine, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Anna R
authors.initials: AR
authors.lastname: Hemnes
authors.affiliation: Division of Allergy, Pulmonary, and Critical Care Medicine, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Ivan M
authors.initials: IM
authors.lastname: Robbins
authors.affiliation: Division of Allergy, Pulmonary, and Critical Care Medicine, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Meredith E
authors.initials: ME
authors.lastname: Pugh
authors.affiliation: Section of Cardiology, Wake Forest Baptist Medical Center, Winston-Salem, North Carolina.
authors.forename: David X
authors.initials: DX
authors.lastname: Zhao
authors.affiliation: Division of Cardiovascular Medicine Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Robert N
authors.initials: RN
authors.lastname: Piana
authors.affiliation: Division of Cardiovascular Medicine Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Pete P
authors.initials: PP
authors.lastname: Fong
authors.affiliation: Division of Cardiovascular Medicine Vanderbilt University Medical Center, Nashville, Tennessee. Electronic address: evan.brittain@vanderbilt.edu.
authors.forename: Evan L
authors.initials: EL
authors.lastname: Brittain
mesh_terms: D000208:Acute Disease; D002121:Calcium Channel Blockers / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D045462:Endothelium-Dependent Relaxing Factors / Q000494:pharmacology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006976:Hypertension, Pulmonary / Q000188:drug therapy / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000494:pharmacology; D011379:Prognosis; D011669:Pulmonary Wedge Pressure / Q000187:drug effects*; D012189:Retrospective Studies; D013997:Time Factors; D014655:Vascular Resistance / Q000187:drug effects*; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*
chemical_list: D002121:Calcium Channel Blockers; D045462:Endothelium-Dependent Relaxing Factors; D009569:Nitric Oxide
keywords: connective tissue disease; hemodynamics; pulmonary arterial hypertension; right heart catheterization; vasodilator