Myocardial tissue characterization by cardiovascular magnetic resonance T1 mapping and pericardial fat quantification in adolescents with morbid obesity. Cardiac dimorphism by gender

Purpose Changes in the myocardial extracellular matrix (ECM) identified using T1 mapping cardiovascular magnetic resonance (CMR) have been only reported in obese adults, but with opposite conclusions. The objectives are to assess the composition of the myocardial ECM in an obese pediatric population without type 2 diabetes by quantifying native T1 time, and to quantify the pericardial fat index (PFI) and their relationship with cardiovascular risk factors. Methods Observational case-control research of 25 morbidly obese adolescents and 13 normal-weight adolescents. Native T1 and T2 times (ms), left ventricular (LV) geometry and function, PFI (g/ht 3 ) and hepatic fat fraction (HFF, %) were calculated by 1.5-T CMR. Results No differences were noticed in native T1 between obese and non-obese adolescents (1000.0 vs. 990.5 ms, p0.73), despite showing higher LV mass values (28.3 vs. 22.9 g/ht 3 , p0.01). However, the T1 mapping values were significantly higher in females (1012.7 vs. 980.7 ms, p < 0.01) while in males, native T1 was better correlated with obesity parameters, particularly with triponderal mass index (TMI) (r = 0.51), and inflammatory cells. Similarly, the PFI was correlated with insulin resistance (r = 0.56), highly sensitive C-reactive protein (r = 0.54) and TMI (r = 0.77). Conclusion Female adolescents possess myocardium peculiarities associated with higher mapping values. In males, who are commonly more exposed to future non-communicable diseases, TMI may serve as a useful predictor of native T1 and pericardial fat increases. Furthermore, HFF and PFI appear to be markers of adipose tissue infiltration closely related with hypertension, insulin resistance and inflammation.