Carotid extra-media thickness in obesity and metabolic syndrome: AÂ novel index of perivascular adipose tissue: Extra-media thickness in obesity and metabolic syndrome

•We test a new hypothesis on a novel ultrasound index: carotid artery extra-media thickness (EMT).•We use several clinical and ultrasound indexes of obesity.•Carotid EMT is increased in patients with metabolic syndrome.•Carotid EMT is associated with risk factors irrespective of obesity measures.•Carotid EMT is a novel index corresponding to periarterial adipose tissue.

ObjectivesWe aimed to evaluate the association between a novel ultrasound index extra-media thickness (EMT), obesity, and metabolic syndrome (MS) using several measures of adiposity.MethodsFour hundred patients were included in the study (age: 60.95 ± 7.3 years, F/M: 35/65%). Both common carotid arteries (CCA) indexes (EMT and intima-media thickness), anthropometric parameters, body fat percentage and ultrasound measures of different fat depots were obtained in all patients. MS was identified using three alternative definitions: International Diabetes Federation 2005 (IDF), National Cholesterol Education Program Adult Treatment Panel III 2001 (NCEP ATP III) and World Health Organization 1998 (WHO).ResultsThe study group included patients with very high (80.2%) or high (19.8%) CV risk (IDF MS: 59.5%). Carotid EMT measures averaged from both sides (±SD) were as follows: mean EMT: 791 ± 126 μm, mean minimum EMT: 731 ± 115 μm and mean maximum EMT: 885 ± 210 μm. Patients with MS, irrespective of its definition and measures of obesity, displayed significantly thicker mean EMT compared to non-MS individuals: 819 ± 129 μm vs 747 ± 113 μm (p < 0.001; IDF), 824 ± 131 μm vs 751 ± 112 μm (p < 0.001; NCEP ATP III) and 825 ± 137 μm vs 773 ± 120 μm (p < 0.001; WHO). Moreover, EMT was related to all major parameters of general obesity, abdominal fat distribution, regional neck subcutaneous fat with weaker association between EMT and epicardial fat thickness. Finally, EMT is associated with an increasing number of CV risk factors.ConclusionsThis is the first study providing novel findings on the relationship between EMT, MS, and adiposity indexes. Our results suggest that EMT may be a new non-invasive index of perivascular adipose tissue corresponding to cardiometabolic risk.

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