title: Survival by stroke volume index in patients with low-gradient normal EF severe aortic stenosis.
abstract: OBJECTIVE
  Low-gradient (LG) severe aortic stenosis (AS) and preserved EF with reduced stroke volume are associated with an adverse prognosis, but the relationship of stroke volume index (SVI) with mortality among a range of values is unknown. We investigated the prognostic impact of SVI in this population.
  
  
  METHODS
  We examined 405 consecutive patients with preserved EF (≥50%) and severe AS (valve area <1.0 cm(2)) with LG (<40 mm Hg) using echocardiography. Patients were stratified into quartiles based on SVI distribution (group 1: <38 mL/m(2) (n=90), group 2: 38-43 mL/m(2) (n=105), group 3: 43-48 mL/m(2) (n=104) and group 4: >48 mL/m(2) (n=106)).
  
  
  RESULTS
  Groups 1 and 2 had poorer survival with medical management compared with 3 and 4 (3-year estimate 46% and 67% vs. 78% and 73%, respectively, p=0.002) although aortic valve replacement referral rate was similar (53%-62%, p=0.57). An inverse relationship was observed between SVI and mortality (HR 1.28 (1.11 to 1.46) per every 5 mL/m(2) decrease in SVI). After multivariable analysis, SVI was the strongest predictor of mortality (HR 0.92 (0.89 to 0.95), p<0.0001). Using different SVI cutpoints, SVI <35 was associated with highest mortality (HR 2.36 (1.49 to 3.73), p<0.001), followed by SVI <38 (HR 2.09 (1.39 to 3.16), p<0.001) and by SVI <43 (HR 2.05 (1.38 to 3.05), p<0.001). Survival with SVI ≥43 was similar to age and sex-matched controls (3-year estimate 84%, p=0.24); survival for SVI <43 was significantly worse (3-year estimate 63%, p<0.001).
  
  
  CONCLUSIONS
  Lower SVI is incrementally associated with mortality in LG severe AS with preserved EF. These findings have implications for classification of AS severity, identification of high-risk groups and subsequent management.
authors.affiliation: Divisions of Cardiovascular Diseases, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
authors.forename: Mackram F
authors.initials: MF
authors.lastname: Eleid
authors.affiliation: Divisions of Cardiovascular Diseases, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Sorajja
authors.affiliation: Divisions of Cardiovascular Diseases, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
authors.forename: Hector I
authors.initials: HI
authors.lastname: Michelena
authors.affiliation: Divisions of Cardiovascular Diseases, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
authors.forename: Joseph F
authors.initials: JF
authors.lastname: Malouf
authors.affiliation: Divisions of Biostatistics, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
authors.forename: Christopher G
authors.identifier: http://orcid.org/0000-0003-1340-0647
authors.initials: CG
authors.lastname: Scott
authors.affiliation: Divisions of Cardiovascular Diseases, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Pellikka
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001024:Aortic Valve Stenosis / Q000000981:diagnostic imaging / Q000401:mortality / Q000503:physiopathology* / Q000601:surgery; D015150:Echocardiography, Doppler; D005260:Female; D019918:Heart Valve Prosthesis Implantation; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011379:Prognosis; D016016:Proportional Hazards Models; D012017:Referral and Consultation; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D013318:Stroke Volume; D013997:Time Factors; D016277:Ventricular Function, Left