Myocardial fibrosis as an early manifestation of hypertrophic cardiomyopathy.
BACKGROUND
Myocardial fibrosis is a hallmark of hypertrophic cardiomyopathy and a proposed substrate for arrhythmias and heart failure. In animal models, profibrotic genetic pathways are activated early, before hypertrophic remodeling. Data showing early profibrotic responses to sarcomere-gene mutations in patients with hypertrophic cardiomyopathy are lacking.


METHODS
We used echocardiography, cardiac magnetic resonance imaging (MRI), and serum biomarkers of collagen metabolism, hemodynamic stress, and myocardial injury to evaluate subjects with hypertrophic cardiomyopathy and a confirmed genotype.


RESULTS
The study involved 38 subjects with pathogenic sarcomere mutations and overt hypertrophic cardiomyopathy, 39 subjects with mutations but no left ventricular hypertrophy, and 30 controls who did not have mutations. Levels of serum C-terminal propeptide of type I procollagen (PICP) were significantly higher in mutation carriers without left ventricular hypertrophy and in subjects with overt hypertrophic cardiomyopathy than in controls (31% and 69% higher, respectively; P<0.001). The ratio of PICP to C-terminal telopeptide of type I collagen was increased only in subjects with overt hypertrophic cardiomyopathy, suggesting that collagen synthesis exceeds degradation. Cardiac MRI studies showed late gadolinium enhancement, indicating myocardial fibrosis, in 71% of subjects with overt hypertrophic cardiomyopathy but in none of the mutation carriers without left ventricular hypertrophy.


CONCLUSIONS
Elevated levels of serum PICP indicated increased myocardial collagen synthesis in sarcomere-mutation carriers without overt disease. This profibrotic state preceded the development of left ventricular hypertrophy or fibrosis visible on MRI. (Funded by the National Institutes of Health and others.)
Ho
Carolyn Y
CY
Cardiovascular Division, Brigham and Women's Hospital, Boston, MA 02115, USA. cho@partners.org
López
Begoña
B
Coelho-Filho
Otavio R
OR
Lakdawala
Neal K
NK
Cirino
Allison L
AL
Jarolim
Petr
P
Kwong
Raymond
R
González
Arantxa
A
Colan
Steven D
SD
Seidman
J G
JG
Díez
Javier
J
Seidman
Christine E
CE
D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000097:blood; D024722:Cardiac Myosins; D002312:Cardiomyopathy, Hypertrophic / Q000097:blood / Q000150:complications* / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D003094:Collagen / Q000096:biosynthesis; D024042:Collagen Type I; D004452:Echocardiography; D005260:Female; D005355:Fibrosis / Q000175:diagnosis / Q000209:etiology; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000209:etiology; D016015:Logistic Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009154:Mutation; D009206:Myocardium / Q000378:metabolism / Q000473:pathology*; D018995:Myosin Heavy Chains / Q000235:genetics; D010446:Peptide Fragments / Q000097:blood*; D010455:Peptides; D011347:Procollagen / Q000097:blood*; D055815:Young Adult; D000099163:Myosin Binding Protein C
D015415:Biomarkers; D024722:Cardiac Myosins; D002352:Carrier Proteins; D003094:Collagen; D024042:Collagen Type I; D018995:Myosin Heavy Chains; D010446:Peptide Fragments; D010455:Peptides; D011347:Procollagen; D000099163:Myosin Binding Protein C; C501641:MYH7 protein, human; C052929:collagen type I trimeric cross-linked peptide; C042813:procollagen type I carboxy terminal peptide
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