Relationship between epicardial fat tissue and left ventricular synchronicity: An observational study

Lipids and diastolic dysfunction: Recent evidence and findings

AIM

Diastolic dysfunction is the decreased flexibility of the left ventricle due to the impaired ability of the myocardium to relax and plays an important role in the pathogenesis of heart failure. Lipid metabolism is a well-known contributor to cardiac conditions, including ventricular function. In this article, we aimed to review the literature addressing the connections between lipids, their storage, and metabolism with left ventricular diastolic dysfunction.

DATA SYNTHESIS

We searched Google scholar, Pubmed, Embase and Researchgate for our keywords: "Diastolic function", "Fat" and "Lipid profile". Initially, 250 articles were selected by title and 84 of them were chosen as most relevant and directly reviewed.

CONCLUSIONS

Alterations of lipid metabolism in cardiac muscle and cardiac lipid content can occur in many conditions, including consumption of a high-fat diet, obesity, metabolic syndrome, and non-alcoholic fatty liver disease (NAFLD). These conditions induce alterations in myocardial lipid metabolism, increase myocardial fat content and epicardial fat thickness and increase inflammation and oxidative stress which ultimately lead to cardiac lipotoxicity and diastolic dysfunction. The effects of lipids on diastolic function can differ based on gender. Lipid profile and metabolism are as important in the pathogenesis of diastolic dysfunction as they are in other cardiovascular disorders. A more careful look at cardiac lipid metabolism in molecular, histological and gross levels results in more precise understanding of its role in myocardial function and leads to development of potential treatments for diastolic dysfunction.

Cardiac CT scanning in coronary artery disease: Epicardial fat volume and its correlation with coronary artery lesions and left ventricular function

Coronary artery disease (CAD) is a major and common disease that poses a threat to human health. Recent studies suggested that epicardial fat may have an important role in the pathogenesis of CAD. Therefore, the association between epicardial fat volume (EFV) and left ventricular function with CAD was investigated in the present study. A total of 61 patients with suspected CAD who underwent CT scanning were enrolled. Baseline data, parameters of left heart function and EFV of the subjects were collected and analyzed. The degree of coronary artery lesions was assessed using the Gensini score. Pearson's correlation analysis and a logistic regression model were applied to assess the association between EFV and risk factors for CAD, the Gensini score and left ventricular function index. A total of 29 female and 32 male subjects with a median age of 63 years were enrolled. The median body mass index (BMI) of the subjects was 23.37 kg/m² and the median EFV was 86.41 cm³. It was revealed that risk factors of CAD, specially hypertension, diabetes mellitus, dyslipidemia, history of myocardial infarction and smoking, had no significant association with the EFV (P>0.05); however, the EFV was significantly positively correlated with the BMI (r=0.479, P<0.0001), interventricular septal thickness (r=0.436, P=0.004), left ventricular posterior wall thickness (r=0.350, P=0.0058), left ventricular end diastolic diameter (r=0.265, P=0.0388), left ventricular mass (r=0.445, P=0.0003) and left ventricular mass index (r=0.371, P=0.0035). However, no correlation was identified between the EFV and the Gensini score (r=0.131, P=0.3137). In conclusion, the EFV measured by cardiac CT scanning was positively correlated with the BMI and left ventricular function, but was not associated with the presence of CAD according to the Gensini scores.

Mitochondrial calcium uniporter inhibition provides cardioprotection in pressure overload-induced heart failure through autophagy enhancement

BACKGROUND

HF incurs high disease burden, and the effectiveness of known HF treatments is unsatisfactory. Therefore, seeking novel therapeutic target of HF is important. The present study aimed to investigate the role of the mitochondrial calcium uniporter (MCU) and its relationship with autophagy in overload-induced heart failure (HF).

METHODS AND RESULTS

In both early-stage and end-stage of pressure overload-induced HF, MCU appeared up-regulated along with heart enlargement, increased microtubule-associated proteins 1A/1B light chain 3B (LC3B) II/I ratio and autophagosome content, damaged cardiac function, and ventricular asynchrony. However, sequestosome-1 (SQSTM1/p62) level decreased indicating blockaded autophagic flux. Seven-week administration of MCU inhibitor ruthenium red improved cardiac function and mitigated its pathological change. MCU inhibition maintained mitochondrial integrity, increased LC3B II/I ratio, up-regulated Parkin and Pink1, and down-regulated SQSTM1/p62. MCU inhibition also alleviated ventricular asynchrony of HF, and this might be related to connexin-43 up-regulation. In vitro study validated intervention on MCU leading to elevation of autophagy and mitophagy. MCU inhibition could partly prevent from excessive cellular enlargement induced by isoprenaline.

CONCLUSIONS

In summary, MCU inhibition played an important role in pressure overload-induced heart failure through autophagy and mitophagy enhancement, and intervention on MCU offered cardioprotective effects. To our knowledge, the role of MCU in HF and its relationship with autophagy and mitophagy are firstly disclosed. Moreover, our study suggests that MCU inhibition could be explored as a novel therapeutic concept in HF.

Relationship between R-R interval and left ventricular systolic synchrony in subjects with coronary artery disease determined using angiography

The aim of this study was to assess the relationship between R-R interval and left ventricular systolic synchrony in subjects with coronary artery disease determined using angiography. A total of 277 subjects who underwent coronary angiography for suspected CAD were recruited in this study. For all subjects, the R-R interval was quantified using simultaneous ECG, and the times to peak systolic longitudinal strain (Tssl) on 17 LV segments were quantified using four-dimensional (4D) speckle tracking echocardiography (STE) and manually measured. The independent predictors of R-R interval using multiple linear regression analyses were the time to peak systolic longitudinal strain in the apical-septal segment (Tssl-Apical-S) (β=0.325, P=0.000), smoking status (β=0.141, P=0.013), and the time to peak systolic longitudinal strain in the basal-anterolateral segment (Tssl-Basal-AL) (β=0.151, P=0.014), which were significantly independently associated with the R-R interval. In multiple regression analyses, smoking status (OR, 1.943; 95% CI, 1.119-3.375, P=0.018), Tssl-Basal-AL (OR, 1.002; 95% CI, 1.000-1.004, P=0.043), the time to peak systolic longitudinal strain in the mid-inferoseptal segment (Tssl-Mid-IS) (OR, 1.008; 95% CI, 1.003-1.013, P=0.004), and Tssl-Apical-S (OR, 1.010; 95% CI, 1.004-1.016, P=0.002) remained independently associated with the risk of a longer R-R interval (the median 849.49 ms was set as the cutoff value) in the population. Our findings may provide the basis for future investigations of LV systolic synchrony and cardiac resynchronization therapy.