Hypertrophic cardiomyopathy phenotype revisited after 50 years with cardiovascular magnetic resonance.
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.
Maron
Martin S
MS
Hypertrophic Cardiomyopathy Center, Division of Cardiology, Tufts Medical Center, Boston, Massachusetts 02111, USA. mmaron@tuftsmedialcenter.org
Maron
Barry J
BJ
Harrigan
Caitlin
C
Buros
Jacki
J
Gibson
C Michael
CM
Olivotto
Iacopo
I
Biller
Leah
L
Lesser
John R
JR
Udelson
James E
JE
Manning
Warren J
WJ
Appelbaum
Evan
E
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
D005682:Gadolinium