Kuronuma K, et al.. Adv Exp Med Biol. 2020;1232:355-360.
Epicardial adipose tissue (EAT), is the visceral fat depot of the heart and produces inflammatory adipokines. It is associated with visceral fat, atrial fibrillation and major adverse cardiovascular events. To prevent unfavourable cardiac events, assessment of peripheral microcirculation in post-cardiac surgical patients is necessary. Near infrared spectroscopy (NIRS) is a non-invasive technique that allows to evaluate peripheral blood flow. Kuronuma K, et al., conducted a study to assess correlations between NIRS changes induced by a vascular occlusion test (VOT) and EAT volume measured by cardiac computed tomography (CCT) in patients with suspected coronary artery disease (CAD).
Correlation between body mass index (BMI) and EAT volume was assessed and compared in patients treated with statin therapy and in those without statin therapy. A NIRS probe was set on the right thenar eminence, and brachial artery blood flow was blocked for 3 min before being released. NIRS parameters included total hemoglobin (ΔcHb), oxyhemoglobin (ΔO2Hb), deoxyhemoglobin (ΔHHb) and tissue oxygenation index (ΔTOI); these parameters were recorded every 0.2 s, continuously. A total of 83 consecutive patients (52 male, median age 69.0 years, median BMI 23.9 kg/m2) were enrolled, and 39 patients were prescribed statins. ΔTOI, ΔcHb and ΔHHb were not correlated with EAT volume (r=−0.08, p=0.46; r=−0.098, p=0.38 and r=0.056, p=0.62, respectively). In the overall study population, a negative correlation was found between ΔTOI and EAT volume in the overall study population (r=−0.236, p=0.03). A strong correlation was observed in the patients without statin therapy (r=−0.488; p<0.001). Conversely, the correlation was absent in the patients with statin therapy (r=0.157; p=0.34) (Figure 1). In all cases, a positive correlation was observed between BMI and EAT volume (r=0.547, p<0.001). A stronger correlation was observed in patients without statin therapy (r=0.722, p<0.001), while a significant but weak correlation was observed in patients with statin therapy (r=0.325, p=0.044) (Figure 2).
These findings suggest that NIRS measurements with VOT may be a useful method to identify patients with high EAT volume and high cardiovascular risks.
Figure 1: Relationship between epicardial adipose tissue volume and changes of oxyhemoglobin in all patients (A) in patients without statin therapy (B) and in patients with statin therapy (C) EATV, epicardial adipose tissue volume; O2Hb, oxyhemoglobin
Figure 2: Relationship between epicardial adipose tissue volume and body mass index in all patients (A), in patients without statin therapy (B) and in patients with statin therapy (C). EATV, epicardial adipose tissue volume; BMI, body mass index
