Abstract
To assess the global and segmental left ventricular (LV) native T1 and extracellular volume fraction (ECV) in children and young adults with hypertrophic cardiomyopathy (HCM) compared to a control cohort. The study population included 21 HCM patients (mean 14.1 ± 4.6 years) and 21 controls (mean 15.7 ± 1.5 years). Native modified Look-Locker inversion recovery sequence was performed before and after contrast injection in 3 short axis planes. Global and segmental LV native T1 and ECV were quantified and compared between HCM patients and controls. Mean native T1 in HCM patients and controls was 1020.4 ± 41.2 and 965.6 ± 30.2 ms respectively (p < 0.0001). Hypertrophied myocardium had significantly higher native global T1 and global ECV compared to non-hypertrophied myocardium in HCM (p < 0.0001, = 0.14 and 0.048, = 0.01 respectively). In a subset of patients, ECV was higher in LV segments with LGE compared to no LGE (p < 0.0001). No significant correlation was identified between global native T1 and ECV and parameters of LV structure and function. Native T1 cut-off of 987 ms provided the highest sensitivity (95 %) and specificity (91 %) to separate HCM patients from controls. Global and segmental native T1 are elevated in HCM patients. LV segments with hypertrophy and/or LGE had higher ECV in a subset of HCM patients. LV native T1 and ECV do not correlate with parameters of LV structure and function. T1 in children and young adults may be used as a non-invasive tool to assess for HCM and related fibrosis.
Highlights
The presence of myocardial fibrosis in hypertrophic cardiomyopathy (HCM) is associated with a wide range of adverse outcomes including ventricular arrhythmia and sudden death in adults
The diagnosis of HCM was based on the demonstration of a non-dilated hypertrophic left ventricle (LV) in the absence of increased LV stress or another cardiac or systemic disease that could result in a similar magnitude of hypertrophy
There was no significant difference in T1 values between HCM patients without and with late gadolinium enhancement (p = 0.07)
Summary
The presence of myocardial fibrosis in hypertrophic cardiomyopathy (HCM) is associated with a wide range of adverse outcomes including ventricular arrhythmia and sudden death in adults. Its presence suggests an adverse prognosis and may provide important therapeutic guidance. Native T1 can be an alternative to routinely used late gadolinium enhancement and has a potential to provide a non-contrast alternative in children. A T1 of > 990 msec yielded a sensitivity of 90% and specificity of 90% to identify patients with HCM (p < 0.05). There was a modest but significant correlation between native T1 and indexed LV mass (r = 0.36, p = 0.03). No correlation was identified between native T1 and heart rate, LV ejection
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