title: Impact of low flow on the outcome of high-risk patients undergoing transcatheter aortic valve replacement.
abstract: OBJECTIVE
  This study sought to assess the impact of baseline left ventricular (LV) outflow, LV ejection fraction (LVEF), and transvalvular gradient on outcomes following transcatheter aortic valve replacement (TAVR) in patients with severe aortic stenosis (AS).
  
  
  BACKGROUND
  Low flow (i.e., reduced stroke volume index [SVi]) can occur with both reduced and preserved LVEF. Low flow is often associated with low gradient despite severe stenosis and with worse outcomes following surgical aortic valve replacement. However, there are few data about the impact of low flow on outcomes following TAVR.
  
  
  METHODS
  We retrospectively analyzed the clinical, Doppler-echocardiographic, and outcome data prospectively collected in 639 patients who underwent TAVR for symptomatic severe AS in 2 Canadian centers.
  
  
  RESULTS
  In this cohort, 334 (52.3%) patients had a low flow (SVi <35 ml/m(2)) and these patients had increased 30-day mortality (11.4 vs. 5.9%, p = 0.01), 2-year all-cause mortality (35.3 vs. 30.9%, p = 0.005), and 2-year cardiovascular mortality (25.7 vs. 16.8%, p = 0.01) compared with patients with normal flow. Reduced flow was an independent predictor of 30-day mortality (odds ratio: 1.94, p = 0.026), cumulative all-cause mortality (hazard ratio: 1.27 per 10 ml/m(2) SVi decrease, p = 0.016), and cumulative cardiovascular mortality (hazard ratio: 1.29 per 10 ml/m(2) decrease, p = 0.04). Despite significant association in univariable analyses, low LVEF and low mean gradient were not found to be independent predictors of outcomes in multivariable analyses.
  
  
  CONCLUSIONS
  Low flow but not low LVEF or low gradient is an independent predictor of early and late mortality following TAVR in high-risk patients with severe AS. SVi should be integrated in the risk stratification process of these patients.
authors.affiliation: Institut Universitaire de Cardiologie et de Pneumologie de Québec/Québec Heart and Lung Institute, Laval University, Québec City, Québec, Canada.
authors.forename: Florent
authors.initials: F
authors.lastname: Le Ven
authors.forename: Mélanie
authors.initials: M
authors.lastname: Freeman
authors.forename: John
authors.initials: J
authors.lastname: Webb
authors.forename: Marie-Annick
authors.initials: MA
authors.lastname: Clavel
authors.forename: Miriam
authors.initials: M
authors.lastname: Wheeler
authors.forename: Éric
authors.initials: É
authors.lastname: Dumont
authors.forename: Chris
authors.initials: C
authors.lastname: Thompson
authors.forename: Robert
authors.initials: R
authors.lastname: De Larochellière
authors.forename: Robert
authors.initials: R
authors.lastname: Moss
authors.forename: Daniel
authors.initials: D
authors.lastname: Doyle
authors.forename: Henrique B
authors.initials: HB
authors.lastname: Ribeiro
authors.forename: Marina
authors.initials: M
authors.lastname: Urena
authors.forename: Luis
authors.initials: L
authors.lastname: Nombela-Franco
authors.forename: Josep
authors.initials: J
authors.lastname: Rodés-Cabau
authors.forename: Philippe
authors.initials: P
authors.lastname: Pibarot
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001024:Aortic Valve Stenosis / Q000401:mortality / Q000503:physiopathology* / Q000601:surgery; D002170:Canada; D006328:Cardiac Catheterization; D015331:Cohort Studies; D015150:Echocardiography, Doppler; D005260:Female; D019918:Heart Valve Prosthesis Implantation; D006801:Humans; D008297:Male; D011379:Prognosis; D011446:Prospective Studies; D012189:Retrospective Studies; D012307:Risk Factors; D013318:Stroke Volume / Q000502:physiology*; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging / Q000503:physiopathology*
keywords: AS; CI; Doppler-echocardiography; HG; HR; LEF; LF; LG; LV; LVEF; MG; NEF; NF; OR; SVi; TAVR; aortic stenosis; confidence interval; hazard ratio; high gradient; left ventricle/ventricular; left ventricular ejection fraction; low ejection fraction; low flow; low gradient; mean gradient; normal ejection fraction; normal flow; odds ratio; stroke volume index; transcather aortic valve implantation; transcatheter aortic valve replacement