Independent association of thigh muscle fat density with vascular events in Korean adults

Abstract

Background: We aimed to explore the associations between thigh muscle fat density and vascular events.

Methods: A total of 3,595 adults (mean age, 57.2 years; women, 1,715 [47.7%]) without baseline cardiovascular events from the Korean Atherosclerosis Study-2 were included. Muscle and fat area at the mid-thigh level were measured by computed tomography (CT) using the following Hounsfield Unit range: 0-30 for low density muscle (LDM); 31-100 for normal density muscle (NDM); and - 250 to - 50 for fat.

Results: During a median follow-up period of 11.8 (4.3-13.9) years, vascular events occurred in 11.6% of men and 5.9% of women. Individuals with vascular events had a larger LDM area (men: 48.8 ± 15.5 cm² vs. 44.6 ± 14.5 cm²; women: 39.4 ± 13.2 cm² vs. 35.0 ± 11.8 cm², both P < 0.001) compared with those who did not have vascular events during the follow-up of at least 5 years. The LDM/NDM ratio was also independently associated with vascular events after adjusting for cardiometabolic risk factors. Moreover, the LDM/NDM ratio improved the prognostic value for vascular events when added to conventional risk factors.

Conclusions: The current study suggests that a higher thigh muscle fat infiltration is associated with an increased risk of developing vascular events among Korean adults.

Keywords: Cardiovascular disease; Coronary artery disease; Ectopic fat; Myosteatosis.

Fig. 1

(A) Measurement of visceral fat area at umbilical level. (B) Measurement of fat area and low density muscle (LDM) and normal density muscle (NDM) area at mid-thigh level. C and D. Representative photos of individuals who had small LDM and large NDM area (C) and who had large LDM and small NDM area (D)

Fig. 2

Incidence of vascular event according to (A) LDM area (cm²) or (B) LDM/NDM ratio (%). Red and blue indicates the participants who did or did not develop the disease, respectively. VE, vascular event; CAD, coronary artery disease; CeVD, cerebrovascular disease; PAD, peripheral artery disease. P value between the groups is listed above the bars

Fig. 3

The Kaplan–Meier survival curve demonstrating the incidence of vascular events over the follow-up period, stratified by the optimal cutoff values for LDM/NDM ratio. Participants with high LDM/NDM ratios are represented by black line and low LDM/NDM ratios are in red line, with the 95% confidence interval in shades

Fig. 4

Summary receiver operating characteristic (ROC) curves for predicting vascular events. (A) Vascular events in men. Model 1 (black solid line) was adjusted for age, HbA1c, hsCRP, hypertension, and dyslipidemia. Model 2 (red dashed line) was further adjusted for LDM/NDM ratio. (B) Vascular events in women. Model 1 was adjusted for age, HbA1c, dyslipidemia, and smoking. Model 2 was further adjusted for LDM/NDM ratio