title: Cine MR imaging of myocardial contractile impairment in patients with hypertrophic cardiomyopathy attributable to Asp175Asn mutation in the alpha-tropomyosin gene.
abstract: OBJECTIVE
  To prospectively investigate the relationship between myocardial contractile impairment and left ventricular (LV) hypertrophy measured at cardiac magnetic resonance (MR) imaging in patients with hypertrophic cardiomyopathy (HCM) caused by the substitution of aspartic acid 175 with asparagine (ie, Asp175Asn mutation) in the alpha-tropomyosin gene (TPM1).
  
  
  METHODS
  The study protocol was approved by the hospital ethics committee, and all subjects gave written informed consent. LV mass, maximal LV wall thickness, and myocardial fractional thickening during systole were measured at cine MR imaging in 24 subjects (11 male, 13 female; mean age, 42 years; age range, 17-68 years) with the Asp175Asn mutation in TPM1 and in 17 healthy volunteers (eight men, nine women; mean age, 38 years; age range, 23-60 years). The proportion of hypokinetic LV segments was calculated as the number of LV segments with fractional thickening of less than 30% divided by the total number of segments measured. Anthropometric and biochemical correlates of LV hypertrophy were determined. Univariate and multiple linear regression analyses were used to investigate the association of the proportion of hypokinetic segments and other correlates of LV hypertrophy with LV mass and maximal wall thickness.
  
  
  RESULTS
  The proportion of hypokinetic segments was higher in patients with HCM than in control subjects (37% +/- 20 [standard deviation] vs 12% +/- 12, P < .001). In stepwise multiple regression analysis, the proportion of hypokinetic segments accounted for 42% (P < .001); the LV end-diastolic volume, for 24% (P = .003); and male sex, for 10% (P = .014) of the variability in LV mass in patients with HCM. The proportion of hypokinetic LV segments, which accounted for 48% of the variability in LV maximal wall thickness (P < .001), was the only variable significantly associated with maximal wall thickness.
  
  
  CONCLUSIONS
  The extent of myocardial contractile impairment is strongly and independently related to LV mass and maximal wall thickness in patients with HCM attributable to the Asp175Asn mutation in TPM1.
authors: Department of Clinical Radiology, Kuopio University Hospital, Puijonlaaksontie 2, Kuopio FIN-70210, Finland.
authors: Petri
authors: P
authors: Sipola
authors: Kirsi
authors: K
authors: Lauerma
authors: Pertti
authors: P
authors: Jääskeläinen
authors: Markku
authors: M
authors: Laakso
authors: Keijo
authors: K
authors: Peuhkurinen
authors: Hannu
authors: H
authors: Manninen
authors: Hannu J
authors: HJ
authors: Aronen
authors: Johanna
authors: J
authors: Kuusisto
mesh_terms: D000328:Adult; D001224:Aspartic Acid / Q000235:genetics; D002312:Cardiomyopathy, Hypertrophic / Q000235:genetics* / Q000503:physiopathology*; D016022:Case-Control Studies; D004452:Echocardiography; D005260:Female; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000235:genetics* / Q000503:physiopathology*; D007091:Image Processing, Computer-Assisted; D016014:Linear Models; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009200:Myocardial Contraction / Q000502:physiology; D011446:Prospective Studies; D018709:Statistics, Nonparametric; D014335:Tropomyosin / Q000235:genetics*
chemical_list: D014335:Tropomyosin; D001224:Aspartic Acid