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Heterogeneity of Intramural Function in Hypertrophic Cardiomyopathy: Mechanistic Insights from MRI Late Gadolinium Enhancement and High-resolution DENSE Strain Maps
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Details:
  • Pubmed ID:
    21576279
  • Pubmed Central ID:
    PMC3460377
  • Funding:
    Z01 HL004607-08 CE/CE/NCIPC CDC HHS/United States
    Z01 HL004607-09/Intramural NIH HHS/United States
    Z01 HL004607-10/Intramural NIH HHS/United States
    ZIA HL004607-11/Intramural NIH HHS/United States
    ZIA HL004607-12/Intramural NIH HHS/United States
    ZIA HL004607-14/Intramural NIH HHS/United States
    ZID HL006140-01/Intramural NIH HHS/United States
  • Document Type:
  • Collection(s):
  • Description:
    Background

    In HCM, myocardial abnormalities are commonly heterogeneous. Two patterns of LGE have been reported: a bright “confluent” and an intermediate intensity abnormality termed “diffuse,” each representing different degrees of myocardial scarring. We used MRI to study the relation between intramural cardiac function and the extent of fibrosis in HCM. The aim of this study was to determine whether excess collagen or myocardial scarring, as determined by late gadolinium enhancement (LGE) MRI, are the primary mechanisms leading to heterogeneous regional contractile function in patients with hypertrophic cardiomyopathy (HCM).

    Methods and Results

    Intramural left ventricular (LV) strain, transmural LV function, and regions of myocardial fibrosis/scarring were imaged in 22 patients with HCM using displacement encoding with stimulated echoes (DENSE), cine MRI and LGE. DENSE systolic strain maps were qualitatively and quantitatively compared with LGE images. Intramural systolic strain by DENSE was significantly depressed within areas of confluent and diffuse LGE but also in the core of the most hypertrophic non-enhanced segment (all p<0.001 vs. non-hypertrophied segments). DENSE demonstrated an unexpected inner rim of largely preserved contractile function and a non-contracting outer wall within hypertrophic segments in 91% of patients.

    Conclusions

    LGE predicted some but not all of the heterogeneity of intramural contractile abnormalities. This indicates that myocardial scarring or excess interstitial collagen deposition does not fully explain the observed contractile heterogeneity in HCM. Thus, myofibril disarray or other non-fibrotic processes affect systolic function in a large number of patients with HCM.