title: Computed tomography imaging to quantify the area of the endocardial subvalvular apparatus in hypertrophic cardiomyopathy - Relationship to outflow tract obstruction and symptoms.
abstract: BACKGROUND
  Abnormalities of the endocardial subvalvular apparatus (SVA), which includes the papillary muscles directly attached to the mitral leaflet and left ventricular apical-basal muscle bundles, are occasionally identified in hypertrophic cardiomyopathy (HCM). Their associations with left ventricular outflow tract (LVOT) obstruction are unknown.
  
  
  METHODS
  We retrospectively reviewed cardiac computed tomography image data sets of 107 consecutive patients with HCM [56 obstructive (HOCM) and 51 non-obstructive (HNOCM)] as well as 53 controls. We evaluated anomalies of the SVA, measured the cross-sectional area of the SVA at the level of the LVOT, and subsequently assessed its correlation with the LVOT pressure gradient with and without medication.
  
  
  RESULTS
  The area of the SVA was greater in HOCM than in HNOCM patients and in the control group (2.5 ± 1.3 cm(2), 1.4 ± 0.8 cm(2), and 0.9 ± 0.6 cm(2), respectively; p < 0.0001). Anomalies in the SVA were more often observed in the HOCM group than in the HNOCM patients and controls (abnormal papillary muscles, 14%, 8%, and 0%, respectively; P = 0.010; LV apical-basal muscle bundles, 73%, 65%, and 45%, respectively; P = 0.0094). Among HOCM patients, logistic regression analysis demonstrated that an SVA area of 2.2 cm(2) was an independent risk factor of residual severe LVOT obstruction (≥50 mmHg) after medication (odds ratio, 10.1; 95% confidence interval, 2.05-49.80).
  
  
  CONCLUSIONS
  An increased area of the endocardial subvalvular apparatus could be an independent risk factor for clinically relevant LVOT obstruction refractory to medication.
authors: Department of Cardiology, Sakakibara Heart Institute, 3-16-1 Asahi-Cho, Fuchu, Tokyo, 183-0003, Japan; Department of Cardiovascular Medicine, The University of Tokyo, Bunkyo, Tokyo, Japan.
authors: Miyu
authors: M
authors: Tajima
authors: Department of Cardiology, Sakakibara Heart Institute, 3-16-1 Asahi-Cho, Fuchu, Tokyo, 183-0003, Japan. Electronic address: niguchi@shi.heart.or.jp.
authors: Nobuo
authors: N
authors: Iguchi
authors: Department of Cardiology, Sakakibara Heart Institute, 3-16-1 Asahi-Cho, Fuchu, Tokyo, 183-0003, Japan.
authors: Yuko
authors: Y
authors: Utanohara
authors: Division of Cardiology, National Center for Global Health and Medicine, Shinjuku, Tokyo, Japan.
authors: Yukio
authors: Y
authors: Hiroi
authors: Department of Cardiology, Sakakibara Heart Institute, 3-16-1 Asahi-Cho, Fuchu, Tokyo, 183-0003, Japan.
authors: Keitaro
authors: K
authors: Mahara
authors: Department of Cardiology, Sakakibara Heart Institute, 3-16-1 Asahi-Cho, Fuchu, Tokyo, 183-0003, Japan.
authors: Tatsunori
authors: T
authors: Niwa
authors: Department of Cardiology, Sakakibara Heart Institute, 3-16-1 Asahi-Cho, Fuchu, Tokyo, 183-0003, Japan.
authors: Morimasa
authors: M
authors: Takayama
authors: Department of Cardiology, Sakakibara Heart Institute, 3-16-1 Asahi-Cho, Fuchu, Tokyo, 183-0003, Japan.
authors: Tetsuya
authors: T
authors: Sumiyoshi
authors: Department of Cardiology, Sakakibara Heart Institute, 3-16-1 Asahi-Cho, Fuchu, Tokyo, 183-0003, Japan.
authors: Hitonobu
authors: H
authors: Tomoike
mesh_terms: D000328:Adult; D000368:Aged; D002312:Cardiomyopathy, Hypertrophic / Q000150:complications / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000503:physiopathology; D002317:Cardiovascular Agents / Q000627:therapeutic use; D015150:Echocardiography, Doppler; D004699:Endocardium / Q000000981:diagnostic imaging* / Q000187:drug effects / Q000503:physiopathology; D005260:Female; D006801:Humans; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010210:Papillary Muscles / Q000000981:diagnostic imaging* / Q000187:drug effects / Q000503:physiopathology; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D014057:Tomography, X-Ray Computed; D016277:Ventricular Function, Left; D014694:Ventricular Outflow Obstruction / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000209:etiology* / Q000503:physiopathology; D017725:Ventricular Pressure
chemical_list: D002317:Cardiovascular Agents
keywords: Beta-blockers; Computed tomography; Endocardial subvalvular apparatus; Left ventricular outflow tract obstruction; Non-obstructive hypertrophic cardiomyopathy; Obstructive hypertrophic cardiomyopathy