title: Cardiac MRI evaluation of hypertrophic cardiomyopathy: left ventricular outflow tract/aortic valve diameter ratio predicts severity of LVOT obstruction.
abstract: OBJECTIVE
  To evaluate if left ventricular outflow tract/aortic valve (LVOT/AO) diameter ratio measured by cardiac magnetic resonance (CMR) imaging is an accurate marker for LVOT obstruction in patients with hypertrophic cardiomyopathy (HCM) compared to Doppler echocardiography.
  
  
  METHODS
  In all, 92 patients with HCM were divided into three groups based on their resting echocardiographic LVOT pressure gradient (PG): <30 mmHg at rest (nonobstructive, n = 31), <30 mmHg at rest, >30 mmHg after provocation (latent, n = 29), and >30 mmHg at rest (obstructive, n = 32). The end-systolic dimension of the LVOT on 3-chamber steady-state free precession (SSFP) CMR was divided by the end diastolic aortic valve diameter to calculate the LVOT/AO diameter ratio.
  
  
  RESULTS
  There were significant differences in the LVOT/AO diameter ratio among the three subgroups (nonobstructive 0.60 ± 0.13, latent 0.41 ± 0.16, obstructive 0.24 ± 0.09, P < 0.001). There was a strong linear inverse correlation between the LVOT/AO diameter ratio and the log of the LVOT pressure gradient (r = -0.84, P < 0.001). For detection of a resting gradient >30 mmHg, the LVOT/AO diameter ratio the area under the receiver operating characteristic (ROC) curve was 0.91 (95% confidence interval [CI] 0.85-0.97). For detection of a resting and/or provoked gradient >30 mmHg, the LVOT/AO diameter ratio area under the ROC curve was 0.90 (95% CI 0.84-0.96).
  
  
  CONCLUSIONS
  The LVOT/AO diameter ratio is an accurate, reproducible, noninvasive, and easy to use CMR marker to assess LVOT pressure gradients in patients with HCM.
authors.affiliation: Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA. vogel-claussen.jens@mh-hannover.de
authors.forename: Jens
authors.initials: J
authors.lastname: Vogel-Claussen
authors.forename: Miguel
authors.initials: M
authors.lastname: Santaularia Tomas
authors.forename: Amit
authors.initials: A
authors.lastname: Newatia
authors.forename: Danielle
authors.initials: D
authors.lastname: Boyce
authors.forename: Aurelio
authors.initials: A
authors.lastname: Pinheiro
authors.forename: Roselle
authors.initials: R
authors.lastname: Abraham
authors.forename: Theodore
authors.initials: T
authors.lastname: Abraham
authors.forename: David A
authors.initials: DA
authors.lastname: Bluemke
mesh_terms: D000465:Algorithms; D001011:Aorta / Q000473:pathology*; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications / Q000473:pathology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D014694:Ventricular Outflow Obstruction / Q000209:etiology* / Q000473:pathology*