title: Rationale and design of the PRognostic Importance of MIcrovascular Dysfunction in asymptomatic patients with Aortic Stenosis (PRIMID-AS): a multicentre observational study with blinded investigations.
abstract: BACKGROUND
  Aortic stenosis (AS) is the commonest valve disorder in the developed world requiring surgery. Surgery in patients with severe asymptomatic AS remains controversial. Exercise testing can identify asymptomatic patients at increased risk of death and symptom development, but with limited specificity, especially in older adults. Cardiac MRI (CMR), including myocardial perfusion reserve (MPR) may be a novel imaging biomarker in AS.
  
  
  OBJECTIVE
  (1) To improve risk stratification in asymptomatic patients with AS and (2) to determine whether MPR is a better predictor of outcome than exercise testing and brain natriuretic peptide (BNP).
  
  
  METHODS
  Multicentre, prospective observational study in the UK, comparing MPR with exercise testing and BNP (with blinded CMR analysis) for predicting outcome.
  
  
  METHODS
  170 asymptomatic patients with moderate-to-severe AS, who would be considered for aortic valve replacement (AVR).
  
  
  METHODS
  Composite of: typical symptoms necessitating referral for AVR and major adverse cardiovascular events.
  
  
  RESULTS
  12-30 months (minimum 12 months).
  MPR will be a better predictor of outcome than exercise testing and BNP.
  The study has full ethical approval and is actively recruiting patients. Data collection will be completed in November 2014 and the study results will be submitted for publication within 6 months of completion.
  
  
  BACKGROUND
  NCT01658345.
authors.affiliation: Department of Cardiovascular Sciences, University of Leicester, Glenfield Hospital, Leicester, UK and NIHR Leicester Cardiovascular Biomedical Research Unit, Glenfield Hospital, Leicester, UK.
authors.forename: Anvesha
authors.initials: A
authors.lastname: Singh
authors.forename: Ian
authors.initials: I
authors.lastname: Ford
authors.forename: John P
authors.initials: JP
authors.lastname: Greenwood
authors.forename: Jamal N
authors.initials: JN
authors.lastname: Khan
authors.forename: Akhlaque
authors.initials: A
authors.lastname: Uddin
authors.forename: Colin
authors.initials: C
authors.lastname: Berry
authors.forename: Stefan
authors.initials: S
authors.lastname: Neubauer
authors.forename: Bernard
authors.initials: B
authors.lastname: Prendergast
authors.forename: Michael
authors.initials: M
authors.lastname: Jerosch-Herold
authors.forename: Bryan
authors.initials: B
authors.lastname: Williams
authors.forename: Nilesh J
authors.initials: NJ
authors.lastname: Samani
authors.forename: Gerry P
authors.initials: GP
authors.lastname: McCann