Heterogeneity of Intramural Function in Hypertrophic Cardiomyopathy: Mechanistic Insights from MRI Late Gadolinium Enhancement and High-resolution DENSE Strain Maps
Published Date:May 16 2011
Source:Circ Cardiovasc Imaging. 4(4):425-434.
Displacement Encoding With Stimulated Echoes
Late Gadolinium Enhancement
Magnetic Resonance Imaging
Magnetic Resonance Imaging, Cine
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
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.
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.
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