Associations Between Visceral and Liver Fat and Cardiac Structure and Function: A UK Biobank Study

Context: Different fat depots have different associations connected to cardiovascular health. Objective: We assessed the associations of abdominal magnetic resonance-quantified visceral adipose tissue (VAT) and liver fat (proton density fat fraction, PDFF) with cardiac magnetic resonance (CMR)-measured cardiac structure and function, and we considered potential mechanisms. Methods: Our study encompassed 10 920 participants from the UK Biobank. We utilized multiple linear regression and multiple mediation analyses to estimate the connections between VAT or PDFF and CMR metrics. Results: Elevated VAT or PDFF exhibited associations with adverse left ventricular (LV) structure (increased wall thickness, concentric LV remodeling), impaired LV function (lower LV global functional index, absolute value of LV global longitudinal strain), and diminished left atrial volumes and stroke volume (all P values were significant). Upon stratifying participants based on VAT and PDFF combinations, all groups, except the low VAT-low PDFF group, were linked to unfavorable cardiac remodeling metrics. The high VAT-high PDFF group displayed the most pronounced cardiac alterations. Multiple mediation analyses were employed to investigate potential mediating roles of systolic blood pressure (SBP), diabetes, dyslipidemia, and blood biomarkers (lipidemia, transaminases) in the adipose-CMR relationship. The findings suggested that VAT or PDFF was related to SBP, diabetes, dyslipidemia, lipid profile, liver function, and glucose. Several potential mediating pathways were identified, primarily through SBP and triglyceride-glucose index, which only partially explained the adipose-CMR relationship. Conclusion: We established the independent associations of VAT and PDFF with unhealthy cardiac structure and function. Furthermore, it identifies SBP and insulin resistance as important mediating factors.