Tissue characterisation and myocardial mechanics using cardiac MRI in children with hypertrophic cardiomyopathy

Abstract

Introduction:Distinguishing between hypertrophic cardiomyopathy and other causes ofleft ventricular hypertrophy can be difficult in children. We hypothesised that cardiac MRI T1 mapping could improve diagnosis of paediatric hypertrophic cardiomyopathy and that measures of myocardial function would correlate with T1 times and extracellular volume fraction.Methods:Thirty patients with hypertrophic cardiomyopathy completed MRI with tissue tagging, T1-mapping, and late gadolinium enhancement. Left ventricular circumferential strain was calculated from tagged images. T1, partition coefficient, and synthetic extracellular volume were measured at base, mid, apex, and thickest area of myocardial hypertrophy. MRI measures compared to cohort of 19 healthy children and young adults. Mann–Whitney U, Spearman’s rho, and multivariable logistic regression were used for statistical analysis.Results:Hypertrophic cardiomyopathy patients had increased left ventricular ejection fraction and indexed mass. Hypertrophic cardiomyopathy patients had decreased global strain and increased native T1 (−14.3% interquartile range [−16.0, −12.1] versus −17.3% [−19.0, −15.7], p < 0.001 and 1015 ms [991, 1026] versus 990 ms [972, 1001], p = 0.019). Partition coefficient and synthetic extracellular volume were not increased in hypertrophic cardiomyopathy. Global native T1 correlated inversely with ejection fraction (ρ = −0.63, p = 0.002) and directly with global strain (ρ = 0.51, p = 0.019). A logistic regression model using ejection fraction and native T1 distinguished between hypertrophic cardiomyopathy and control with an area under the receiver operating characteristic curve of 0.91.Conclusion:In this cohort of paediatric hypertrophic cardiomyopathy, strain was decreased and native T1 was increased compared with controls. Native T1 correlated with both ejection fraction and strain, and a model using native T1 and ejection fraction differentiated patients with and without hypertrophic cardiomyopathy.

Cardiac magnetic resonance diastolic indices correlate with ventricular filling pressures in pediatric heart transplant recipients

“…T1 increases with myocardial edema and fibrosis and is also impacted by myocyte changes. 29 ECV is more specific to the extracellular matrix and increases with any causes of extracellular matrix expansion, specifically edema or fibrosis. 30 We hypothesized that diffuse fibrosis and edema would correlate with PCWP and RAP; however, while both markers increased with increasing PCWP and RAP, neither reached statistical significance.…”

A Comprehensive Assessment of Cardiomyopathies through Cardiovascular Magnetic Resonance: Focus on the Pediatric Population

“…In pediatric patients, diffusely increased T1 values and decreased global longitudinal strain values were found in HCM patients compared to controls [63], as a sign of global involvement of the myocardium. Regarding ECV values, which reflect the presence of fibrosis in the interstitial space, a recent CMR study outlined how septal ECV values were not significantly increased after surgical septal myectomy when performed in early childhood in HCM with LVOT obstruction resistant to medical therapy [64].…”

Cardiac MRI in diagnosis, prognosis, and follow-up of hypertrophic cardiomyopathy in children: current perspectives

“…Native T1 and ECV are both representatives of extracellular matrix expansion, which is seen in the presence of interstitial fibrosis. 36 , 37 HCM patients are characterised by prolonged T1 relaxation times and native T1, together with ECV expansion. 37 Parametric mapping for diffuse interstitial fibrosis is therefore complementary to LGE, which allows for the identification of focal areas of myocardial fibrosis.…”

“… 23 , 42 , 44 Increased native T1 values and expansion of the ECV are seen in paediatric HCM patients as an expression of focal myocardial fibrosis. 37 , 42 Impaired myocardial perfusion can be observed in affected myocardial segments in the absence of coronary artery disease. 38 …”