title: Velocity ratio predicts outcomes in patients with low gradient severe aortic stenosis and preserved EF.
abstract: OBJECTIVE
  To evaluate the usefulness of velocity ratio (VR) in patients with low gradient severe aortic stenosis (LGSAS) and preserved EF.
  
  
  BACKGROUND
  LGSAS despite preserved EF represents a clinically challenging entity. Reliance on mean pressure gradient (MPG) may underestimate stenosis severity as has been reported in the context of paradoxical low flow, LGSAS. On the other hand, grading of stenosis severity by aortic valve area (AVA) may overrate stenosis severity due to erroneous underestimation of LV outflow tract (LVOT) diameter, small body size or inconsistencies in cut-off values for severe stenosis. We hypothesised that VR may have conceptual advantages over MPG and AVA, predict clinical outcomes and thereby be useful in the management of patients with LGSAS.
  
  
  METHODS
  Patients from the prospective Simvastatin and Ezetimibe in Aortic Stenosis (SEAS) study with an AVA<1.0 cm(2), MPG≤40 mm Hg and EF≥55% and asymptomatic at baseline were stratified according to VR with a cut-off value of 0.25. Outcomes were evaluated according to aortic valve-related events and cardiovascular death.
  
  
  RESULTS
  Of 435 patients with LGSAS, 197 (45%) had VR<0.25 suggesting severe and 238 (55%) had VR≥0.25 suggesting non-severe stenosis. Aortic valve-related events (mean follow-up 42±14 months) were more frequent in patients with VR<0.25 (57% vs 41%; p<0.001) as was cardiovascular death within the first 24 months (p<0.05). In multivariable Cox regression analysis, MPG was the strongest independent predictor of aortic valve events (p<0.001) followed by VR (p<0.02). Adjusting AVA by VR increased predictive accuracy for aortic valve events (area under the receiver operating curve 0.62 (95% CI 0.57 to 0.67) vs 0.56 (95% CI 0.51 to 0.61) for AVA, p=0.02) with net reclassification improvement calculated at 0.36 (95% CI 0.17 to 0.54, p<0.001). VR did not improve the prediction of clinical events by MPG.
  
  
  CONCLUSIONS
  In the difficult setting of LGSAS, VR shows a strong association with valve-related events and-although not outperforming MPG-may be particularly useful in guiding clinical management.
  
  
  BACKGROUND
  NCT00092677.
authors.affiliation: University Heart Center Freiburg, Bad Krozingen, Germany.
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Jander
authors.affiliation: University Heart Center Freiburg, Bad Krozingen, Germany.
authors.forename: Willibald
authors.initials: W
authors.lastname: Hochholzer
authors.affiliation: Department of Cardiology, University Hospital Basel, Basel, Switzerland.
authors.forename: Beat A
authors.initials: BA
authors.lastname: Kaufmann
authors.affiliation: Department of Cardiology, Asklepios Clinic St. Georg, Hamburg, Germany.
authors.forename: Edda
authors.initials: E
authors.lastname: Bahlmann
authors.affiliation: Department of Clinical Science, University of Bergen, Bergen, Norway.
authors.forename: Eva
authors.initials: E
authors.lastname: Gerdts
authors.affiliation: Department of Medicine, Skellefteå, Sweden Institution of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden.
authors.forename: Kurt
authors.initials: K
authors.lastname: Boman
authors.affiliation: Cardiothoracic Centre, Guys & St Thomas Hospital Trust, London, UK.
authors.forename: John B
authors.initials: JB
authors.lastname: Chambers
authors.affiliation: Heart Center Rostock, University of Rostock, Rostock, Germany.
authors.forename: Christoph A
authors.initials: CA
authors.lastname: Nienaber
authors.affiliation: Department of Cardiology, University Hospitals of South Manchester, Manchester, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Ray
authors.affiliation: Division of Cardiology, Oslo University Hospital, Aker, Norway.
authors.forename: Anne
authors.initials: A
authors.lastname: Rossebo
authors.affiliation: University of Oslo and Oslo University Hospital, Ullevål, Centre of Preventive Medicine, Oslo, Norway.
authors.forename: Terje R
authors.initials: TR
authors.lastname: Pedersen
authors.affiliation: Department of Cardiology, Glostrup, Copenhagen, Denmark.
authors.forename: Kristian
authors.initials: K
authors.lastname: Wachtell
authors.affiliation: University Heart Center Freiburg, Bad Krozingen, Germany.
authors.forename: Christa
authors.initials: C
authors.lastname: Gohlke-Bärwolf
authors.affiliation: University Heart Center Freiburg, Bad Krozingen, Germany.
authors.forename: Franz-Josef
authors.initials: FJ
authors.lastname: Neumann
authors.affiliation: University Heart Center Freiburg, Bad Krozingen, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Minners
mesh_terms: D000368:Aged; D000924:Anticholesteremic Agents / Q000627:therapeutic use; D001024:Aortic Valve Stenosis / Q000188:drug therapy / Q000401:mortality / Q000503:physiopathology*; D001384:Azetidines / Q000627:therapeutic use; D001783:Blood Flow Velocity / Q000502:physiology; D004452:Echocardiography; D000069438:Ezetimibe; D005260:Female; D006333:Heart Failure / Q000209:etiology; D006801:Humans; D008297:Male; D011446:Prospective Studies; D012372:ROC Curve; D019821:Simvastatin / Q000627:therapeutic use; D013318:Stroke Volume / Q000502:physiology
chemical_list: D000924:Anticholesteremic Agents; D001384:Azetidines; D019821:Simvastatin; D000069438:Ezetimibe