The interaction of lipomatous hypertrophy of the interatrial septum with pericardial adipose tissue biomarkers by computed tomography.

OBJECTIVE

Novel pericardial adipose tissue imaging biomarkers are currently under investigation for cardiovascular risk stratification. However, a specific compartment of the epicardial adipose tissue (EAT), lipomatous hypertrophy of the interatrial septum (LHIS), is included in the pericardial fat volume (PCFV) quantification software. Our aim was to evaluate LHIS by computed tomography angiography (CTA), to elaborate differences to other pericardial adipose tissue components (EAT) and paracardial adipose tissue (PAT), and to compare CT with [18F]FDG-PET.

MATERIALS AND

METHODS

Of 6983 patients screened who underwent coronary CTA for clinical indications, 190 patients with LHIS were finally included (age 62.8 years ± 9.6, 31.6% females, BMI 28.5 kg/cm2 ± 4.7) in our retrospective cohort study. CT images were quantified for LHIS, EAT, and PAT density (HU), and total PCFV, with and without LHIS, was calculated. CT was compared with [18F]FDG-PET if available.

RESULTS

CT-density of LHIS was higher (- 22.4 HU ± 22.8) than all other pericardial adipose tissue components: EAT right and left (97.4 HU ± 13 and - 95.1 HU ± 13) PAT right and left (- 107.5 HU ± 13.4 and - 106.3 HU ± 14.5) and PCFV density -83.3 HU ± 5.6 (p < 0.001). There was a mild association between LHIS and PAT right (Beta 0.338, p = 0.006, 95% CI: 0.098-577) and PAT left (Beta 0.249, p = 0.030; 95% CI: 0.024-0.474) but not EAT right (p = 0.325) and left (p = 0.351), and not with total PCFV density (p = 0.164). The segmented LHIS volume comprised 3.01% of the total PCFV, and 4.3% (range, 2.16-11.7%) in those with LHIS > 9 mm. [18F]FDG-PET: LHIS was tracer uptake positive in 83.3% (37.5%: mild and 45.8%: minimal) of 24 patients.

CONCLUSIONS

LHIS is a distinct compartment of PCFV with higher density suggesting brown fat and has no consistent association with EAT, but rather with PAT.

CLINICAL RELEVANCE STATEMENT: LHIS should be recognized as a distinct compartment of the EAT, when using EAT for cardiovascular risk stratification.

KEY POINTS: LHIS is currently included in EAT quantification software. LHIS density is relatively high, it is not associated with EAT, and has a high [18F]FDG-PET positive rate suggesting brown fat. LHIS is a distinct compartment of the EAT, and it may act differently as an imaging biomarker for cardiovascular risk stratification.