Myocardial t1 mapping: relation of t1 values to myocardial perfusion, early gadolinium enhancement and late gadolinium enhancement in hypertrophic cardiomyopathy
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Date
2019-12
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SCTIMST
Abstract
Hypertrophic cardiomyopathy (HCM) is a disorder of myocardium with a genetic basis,
characterized by an increase in myocardial thickness, non-dilated left ventricle and increased
in ejection fraction(1). Incidence is believed to be 1 in 500 people(2) with heterogeneous
phenotypic expression. Natural history is variable presenting as sudden cardiac death, heart
failure or arrhythmias. HCM is usually a diagnosis of exclusion, while other ethology of LV
hypertrophy needs to be ruled out. Most common differential diagnosis are hypertension,
valvular heart diseases and infiltrative cardiomyopathies(2). HCM is defined as a wall
thickness of > 15 mm either any echocardiography, Computed tomography or cardiac magnetic
resonance imaging (CMR), without any identifiable cause(3). Cardiac involvement is usually
asymmetric, most commonly involving the basal septum, followed by apical and mid cavity
involvement. Echocardiogram is usually the first modality for diagnosis and assessment of
HCM. CMR is the established modality for diagnosis, risk stratification, and management of
the patients diagnosed with HCM. Myocardial fibrosis has proven to be associated with severe
hypertrophy, and an increase in fibrosis reflects onto failing LV function and risk of sudden
cardiac death secondary to arrythmias in patients of HCM(4). Myocardial fibrosis determined
by Late gadolinium enhancement (LGE) has been established as the maker for future risk of
sudden cardiac death(5). Increase in myocardial crypts in phenotype positive HCM is
associated with particular gene mutations(6). These crypts can be assessed using Early
gadolinium enhancement (EGE) sequence which can predict areas of subtle changes even
before fibrosis sets in.
Assessment of LGE requires CMR contrast for fibrosis quantification. T1 mapping is a novel
technique which can assess the local/diffuse fibrosis without the requirement of an MR contrast
agent. Native T1 maps have proven to be a cost-effective method or fibrosis assessment without 10
exposure to gadolinium-based contrast agent(7). Microvascular perfusion defects in HCM
patients is an important marker of prognosis and future arrhythmic episodes causing sudden
cardiac death(8).
This study was aimed at determining the relationship between Early gadolinium enhancement
(EGE)/Late gadolinium enhancement (LGE) and native T1 values in patients of hypertrophic
cardiomyopathy.