title: Hypertrophic cardiomyopathy phenotype revisited after 50 years with cardiovascular magnetic resonance.
abstract: OBJECTIVE
  Our purpose was to characterize the pattern and distribution of left ventricular (LV) hypertrophy by cardiovascular magnetic resonance (CMR) to more precisely define phenotypic expression and its clinical implications in hypertrophic cardiomyopathy (HCM).
  
  
  BACKGROUND
  Based on prior pathologic and 2-dimensional echocardiographic studies, HCM has been regarded as a disease characterized by substantial LV wall thickening.
  
  
  METHODS
  Cine and late gadolinium enhancement CMR were performed in 333 consecutive HCM patients (age 43 +/- 17 years).
  
  
  RESULTS
  Basal anterior LV free wall and the contiguous anterior ventricular septum were the most commonly hypertrophied segments (n = 256; 77%). LV hypertrophy was focal (involving < or = 2 segments [< or = 12% of LV]) in 41 patients (12%), intermediate (3 to 7 segments [13% to 49% of LV]) in 112 patients (34%), and diffuse (> or = 8 segments [> or = 50% of LV]) in 180 patients (54%); 42 patients (13%) showed hypertrophied segments separated by regions of normal thickness. The number of hypertrophied segments was greater in patients with LV outflow tract obstruction (> or = 30 mm Hg) than without (10 +/- 4 vs. 8 +/- 4 per patient; p = 0.0001) and was associated with an advanced New York Heart Association functional class (p = 0.007). LV wall thickness was greater in segments with late gadolinium enhancement than without (20 +/- 6 mm vs. 16 +/- 6 mm; p < 0.001). We also identified 40 (12%) of HCM patients with segmental LV hypertrophy largely confined to the anterolateral free wall, posterior septum, or apex, which was underestimated or undetected by echocardiography.
  
  
  CONCLUSIONS
  Although diverse, patterns of LV hypertrophy are usually not extensive in HCM, involving < or = 50% of the chamber in about one-half the patients, and are particularly limited in extent in an important minority. Contiguous portions of anterior free wall and septum constituted the predominant region of wall thickening, with implications for clinical diagnosis. These observations support an emerging role for CMR in the contemporary evaluation of patients with HCM.
authors: Hypertrophic Cardiomyopathy Center, Division of Cardiology, Tufts Medical Center, Boston, Massachusetts 02111, USA. mmaron@tuftsmedialcenter.org
authors: Martin S
authors: MS
authors: Maron
authors: Barry J
authors: BJ
authors: Maron
authors: Caitlin
authors: C
authors: Harrigan
authors: Jacki
authors: J
authors: Buros
authors: C Michael
authors: CM
authors: Gibson
authors: Iacopo
authors: I
authors: Olivotto
authors: Leah
authors: L
authors: Biller
authors: John R
authors: JR
authors: Lesser
authors: James E
authors: JE
authors: Udelson
authors: Warren J
authors: WJ
authors: Manning
authors: Evan
authors: E
authors: Appelbaum
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002312:Cardiomyopathy, Hypertrophic / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000235:genetics; D002648:Child; D004452:Echocardiography; D005260:Female; D005355:Fibrosis; D005682:Gadolinium; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000235:genetics; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D011446:Prospective Studies; D011877:Radionuclide Imaging; D013997:Time Factors; D014694:Ventricular Outflow Obstruction / Q000175:diagnosis / Q000235:genetics; D055815:Young Adult
chemical_list: D005682:Gadolinium