Coronary Flow Dynamics Measured by Computed Tomography Angiography

Serum FGF21 concentration is associated with hypertriglyceridaemia, hyperinsulinaemia and pericardial fat accumulation, independently of obesity, but not with current coronary artery status

OBJECTIVE

Fibroblast growth factor 21 (FGF21) is an emerging metabolic regulator associated with glucose and lipid metabolism. However, previous studies of FGF21 have been largely confounded by obesity, and data are limited for advanced outcomes such as coronary artery disease (CAD) and ectopic fat accumulation. We investigated the associations between serum FGF21 concentrations and glucose/lipid metabolism, CAD, and pericardial fat deposition in subjects strictly matched for obesity parameters.

DESIGN, PATIENTS AND MEASUREMENTS

We enrolled 189 patients who had undergone cardiac multidetector coronary computed tomography. We measured cardiometabolic parameters and serum FGF21 levels within body mass index (BMI)-matched groups. Correlations and linear regressions were analysed among serum FGF21 levels, pericardial fat volumes and cardiometabolic parameters. Serum FGF21 concentrations were compared in patients with and without diabetes, metabolic syndrome (MS) or CAD.

RESULTS

Serum FGF21 concentrations were significantly higher in BMI-matched patients with MS (107·2 ± 83·6 vs 82·1 ± 67·4 ng/l without MS, P < 0·05), but not among those with diabetes (84·3 ± 56·4 vs 96·3 ± 98·9 ng/l without diabetes, P = 0·300) or CAD (89·6 ± 65·8 vs 84·2 ± 83·1 ng/l without CAD, P = 0·633). Serum FGF21 concentrations correlated positively with triglycerides, low-density lipoprotein-cholesterol, insulin, HOMA-IR and pericardial fat volume. They showed an independent association with pericardial fat volume (β = 0·111 ± 0·053, P < 0·05).

CONCLUSIONS

Serum FGF21 concentrations were significantly associated with lipid profiles, insulin resistance, pericardial fat volume and MS, independently of obesity, but not with overt CAD or diabetes.

Associations between thyroid hormone levels and regional fat accumulation in euthyroid men

OBJECTIVE

Body adiposity, especially ectopic fat accumulation, has a range of metabolic and cardiovascular effects. This study aimed to investigate whether thyroid function is associated with various regional fat quantities in euthyroid subjects.

METHODS

A total of 100 euthyroid men (free triiodothyronine (fT3), 4.77±1.21 pg/ml; free thyroxine (fT4), 1.38±0.21 ng/dl; and TSH, 2.09±0.91 μIU/ml) were enrolled in this cross-sectional study. We measured accumulated regional fat using 64-slice multi-detector computed tomography. Multiple linear regression analysis was used to determine whether accumulated fat in each region was associated with clinical parameters after adjusting for age.

RESULTS

FT3 was inversely correlated with BMI (R=0.232, P=0.029) and LDL cholesterol level (R=0.277, P=0.019). FT4 was inversely correlated with waist circumference (R=0.350, P=0.008) and BMI (R=0.355, P0.001). In multiple linear regression analysis, fT3 and fT4 levels were significantly associated with pericardial fat volume (fT3: B=-0.079, 95% CI -0.142 to -0.017, P=0.013; fT4: B=-0.411, 95% CI -0.780 to -0.042, P=0.030) in euthyroid men, independent of age. FT3 level was inversely associated with intramuscular fat area (B=-0.059, 95% CI -0.106 to -0.011, P=0.016) and hepatic fat quantity (B=-0.237, 95% CI -0.441 to -0.033, P=0.024) in euthyroid men, independent of age.

CONCLUSIONS

In euthyroid men, low levels of fT3 and fT4 were significantly associated with increased pericardial fat volume and BMI.