Epicardial adipose tissue thickness as an independent predictor of ventricular tachycardia recurrence following ablation

Epicardial fat and ventricular arrhythmias

The arrhythmogenic role of epicardial adipose tissue (EAT) in atrial arrhythmias is well established, but its effect on ventricular arrhythmias has been significantly less investigated. Since ventricular arrhythmias are thought to cause 75%-80% of cases of sudden cardiac death, this is not a trivial issue. We provide an overview of clinical data as well as experimental and molecular data linking EAT to ventricular arrhythmias, attempting to dissect possible mechanisms and indicate future directions of research and possible clinical implications. However, despite a wealth of data indicating the role of epicardial and intramyocardial fat in the induction and propagation of ventricular arrhythmias, unfortunately there is currently no direct evidence that indeed EAT triggers arrhythmia or can be a target for antiarrhythmic strategies.

Localized cardiomyocyte lipid accumulation is associated with slowed epicardial conduction in rats

Transmural action potential duration differences and transmural conduction gradients aid the synchronization of left ventricular repolarization, reducing vulnerability to transmural reentry and arrhythmias. A high-fat diet and the associated accumulation of pericardial adipose tissue are linked with conduction slowing and greater arrhythmia vulnerability. It is predicted that cardiac adiposity may more readily influence epicardial conduction (versus endocardial) and disrupt normal transmural activation/repolarization gradients. The aim of this investigation was to determine whether transmural conduction gradients are modified in a rat model of pericardial adiposity. Adult Sprague-Dawley rats were fed control/high-fat diets for 15 wk. Left ventricular 300 µm tangential slices were generated from the endocardium to the epicardium, and conduction was mapped using microelectrode arrays. Slices were then histologically processed to assess fibrosis and cardiomyocyte lipid status. Conduction velocity was significantly greater in epicardial versus endocardial slices in control rats, supporting the concept of a transmural conduction gradient. High-fat diet feeding increased pericardial adiposity and abolished the transmural conduction gradient. Slowed epicardial conduction in epicardial slices strongly correlated with an increase in cardiomyocyte lipid content, but not fibrosis. The positive transmural conduction gradient reported here represents a physiological property of the ventricular activation sequence that likely protects against reentry. The absence of this gradient, secondary to conduction slowing and cardiomyocyte lipid accumulation, specifically in the epicardium, indicates a novel mechanism by which pericardial adiposity may exacerbate ventricular arrhythmias.

The relationship between frequent premature ventricular complexes and epicardial adipose tissue volume

Background

Epicardial adipose tissue (EAT) is related to atrial fibrillation. The association between EAT volume and premature ventricular complexes (PVCs) remains unclear. Our study aimed to investigate the effect of EAT volume on the risk of frequent PVCs and burden levels of PVCs.

Methods

This observational study retrospectively recruited consecutive patients who had consultation between 2019 and 2021 at the First Affiliated Hospital of Zhengzhou University. Frequent PVC patients (n = 402) and control patients (n = 402) undergoing non-contrast computed tomography (CT) were enrolled. We selected evaluation criteria for the conduct of a 1:1 propensity score matching (PSM) analysis. Multivariable logistic analysis was used to investigate factors related to frequent PVCs. Furthermore, the determinants of EAT volume and the burden levels of PVCs were evaluated.

Results

Patients with PVCs had a significantly larger EAT volume than control patients. EAT volume was significantly larger in male PVC patients with BMI ≥24 kg/m2, diabetes mellitus, and E/A ratio <1. EAT volume was independently associated with PVCs. Moreover, the larger EAT volume was an independent predictor for the high burden level of PVCs. We revealed that the risk of high PVC burden level was increased with the rising of EAT volume by restricted cubic splines.

Conclusions

EAT volume was larger in frequent PVC patients than in control patients, regardless of other confounding factors. A large EAT volume was independently associated with high burden levels of PVCs. EAT volume may be a new mechanism to explain the pathogenesis of PVCs.

The relationship between epicardial adipose tissue thickness and arrhythmias in patients with hypertension: a 3.0T cardiac magnetic resonance study

OBJECTIVES

To investigate the relationship between epicardial adipose tissue (EAT) thickness using cardiac magnetic resonance imaging (CMR) and arrhythmias in hypertensive patients.

METHODS

Fifty-four hypertensive patients with arrhythmias (HTN [arrhythmias+]), 79 hypertensive patients without arrhythmias (HTN [arrhythmias-]), and 39 normal controls were retrospectively enrolled. EAT thickness was measured on cine images. Analysis of covariance with Bonferroni's post hoc correction, Pearson or Spearman analysis, receiver operating characteristic curve, and intraclass correlation coefficient analysis were performed.

RESULTS

All hypertensive patients had impaired left ventricular (LV) and left atrial (LA) myocardial deformation, and HTN (arrhythmias+) patients displayed higher LV myocardial native T1, LA volume index, and increased EAT thickness than HTN (arrhythmias-) patients and normotensive controls. The presence of LV late gadolinium enhancement (LGE) was higher in hypertensive patients with arrhythmias than in those without arrhythmias. EAT thickness metrics significantly correlated with age, systolic blood pressure, body mass index, triglycerides and high-density lipoprotein levels, LV mass index and native T1 (all p < 0.05). EAT thickness parameters were able to differentiate hypertensive patients with arrhythmias from those without arrhythmias and normal controls, and the right ventricular free wall had the highest diagnostic performance.

CONCLUSION

An accumulation of EAT thickness could further induce cardiac remodeling, promote myocardial fibrosis, and exaggerate function in hypertensive patients with arrhythmias.

ADVANCES IN KNOWLEDGE

CMR-derived EAT thickness metrics could be a useful imaging marker for differentiating hypertensive patients with arrhythmias, which might be a potential target for the prevention of cardiac remodeling and arrhythmias.

Radiomic Phenotype of Periatrial Adipose Tissue in the Prognosis of Late Postablation Recurrence of Idiopathic Atrial Fibrillation

The aim of the study is to find new predictors of postablation atrial fibrillation (AF) recurrence in patients with lone AF using a texture analysis of the periatrial adipose tissue (PAAT) of the left atrium.

Materials and Methods

Forty-three patients admitted for lone AF catheter ablation, who had undergone multispiral coronary angiography, were enrolled in the study. PAAT segmentation was performed using 3D Slicer application followed by extraction of 93 radiomic features. At the end of the follow-up period, patients were divided into 2 groups depending on the presence or absence of AF recurrence.

Results

12 months of follow-up after catheter ablation, postablation AF recurrence was reported in 19 out of 43 patients. Of 93 extracted radiomic features of PAAT, statistically significant differences were observed for 3 features of the Gray Level Size Zone matrix. At the same time, only one radiomic feature of PAAT, Size Zone Non Uniformity Normalized, was an independent predictor of postablative recurrence of AF after catheter ablation and 12 months of follow-up (McFadden's R²=0.451, OR - 0.506, 95% CI: 0.331‒0.776, p<0.001).

Conclusion

The radiomic analysis of periatrial adipose tissue may be considered as a promising non-invasive method for predicting adverse outcomes of the catheter treatment, which opens the possibilities for planning and correction of patient management tactics after intervention.

Radiomic phenotype of epicardial adipose tissue in the prognosis of atrial fibrillation recurrence after catheter ablation in patients with lone atrial fibrillation

Background

Epicardial adipose tissue (EAT) has been considered as one of the probable triggers of atrial fibrillation (AF). CT‐rediomics is a perspective noninvasive method of assessment of EAT. We evaluate the radiomic phenotype of EAT in patients with lone AF in the prognosis of AF recurrence after catheter ablation.

Methods

A total of 43 patients with lone AF referred for CA and 20 out‐hospital patients without arrhythmia underwent multidetector computed tomography coronary angiography. Segmentation of EAT and extraction radiomic features were performed on calcium scoring series using by 3D‐Slicer. Clinical follow‐up was performed for 12 months period after the CA.

Results

EAT in patients with lone AF had a distinct radiomic phenotype. Thus, 45 of 93 calculated radiomic features, volume and attenuation of EAT were significantly different between patients with lone AF and persons without any arrhythmia. In addition, 17 radiomic features were significantly different in subgroups with and without AF recurrence. Multivariate regression analysis demonstrated that only gray level nonuniformity normalized (GLSZM) was an independent predictor of AF recurrence (OR 1.0027, 95%CI 1.0009–1.0044, p = 0.002). ROC analysis data showed that GLSZM >1227.4 indicates high probability of AF recurrence during 12 months (sensitivity 89.4%, specificity 70.8%, AUC: 0.809; p = 0.001).

Conclusion

The radiomic parameter GLSZM is associated with late AF recurrence after CA in patients with lone AF. In current study GLSZM was a stronger predictor of lone AF recurrence in multivariate analysis comparing with other established risk factors and EAT volume and attenuation.

Epicardial adipose tissue as a mediator of cardiac arrhythmias

Obesity is associated with higher risks of cardiac arrhythmias. Although this may be partly explained by concurrent cardiometabolic ill-health, growing evidence suggests that increasing adiposity independently confers risk for arrhythmias. Among fat depots, epicardial adipose tissue (EAT) exhibits a proinflammatory secretome and, given the lack of fascial separation, has been implicated as a transducer of inflammation to the underlying myocardium. The present review explores the mechanisms underpinning adverse electrophysiological remodeling as a consequence of EAT accumulation and the consequent inflammation. We first describe the physiological and pathophysiological function of EAT and its unique secretome and subsequently discuss the evidence for ionic channel and connexin expression modulation as well as fibrotic remodeling induced by cytokines and free fatty acids that are secreted by EAT. Finally, we highlight how weight reduction and regression of EAT volume may cause reverse remodeling to ameliorate arrhythmic risk.

Cardiac Adiposity and Arrhythmias: The Role of Imaging

Increased cardiac fat depots are metabolically active tissues that have a pronounced pro-inflammatory nature. Increasing evidence supports a potential role of cardiac adiposity as a determinant of the substrate of atrial fibrillation and ventricular arrhythmias. The underlying mechanism appears to be multifactorial with local inflammation, fibrosis, adipocyte infiltration, electrical remodeling, autonomic nervous system modulation, oxidative stress and gene expression playing interrelating roles. Current imaging modalities, such as echocardiography, computed tomography and cardiac magnetic resonance, have provided valuable insight into the relationship between cardiac adiposity and arrhythmogenesis, in order to better understand the pathophysiology and improve risk prediction of the patients, over the presence of obesity and traditional risk factors. However, at present, given the insufficient data for the additive value of imaging biomarkers on commonly used risk algorithms, the use of different screening modalities currently is indicated for personalized risk stratification and prognostication in this setting.

Epicardial adipose tissue predicted prolonged QTc interval in patients with arterial hypertension

Introduction: It is important to identify those at higher risk for ventricular arrhythmia among hypertensive patients. Epicardial adipose tissue (EAT) leads to electromechanical changes in the heart by endocrine and paracrine effects with cytokines and mediators. Higher amount of EAT carries the risk of QT prolongation. Therefore, we investigated the association between EAT thickness and QTc interval in patients with arterial hypertension. Methods: A total of 230 patients who previously diagnosed with arterial hypertension between February 2019 to March 2020 were included in the study. Patients with atrial fibrillation, U-wave, atrioventricular block, left anterior or posterior fascicular block, right bundle branch block, left bundle branch block, and taking QT-prolonging medication were excluded. The corrected QT (QTc) interval was calculated with Bazzet's formula following the calculated QT interval in the semi-automatic application tool. EAT was measured at the point on the free wall of the right ventricle using transthoracic echocardiography. Results: The mean age was 62.1 ± 11.4 years and 95 (41.3%) of the patients were male. QTc was over 450 ms were considered as the prolonged interval. Both groups were similar in terms of age (p = .862), gender (p = .265) and other demographic characteristics. Left ventricle mass index (LVMI) (82.5 ± 29.5 vs 91.9 ± 32.6 g/1.7.m², p = .051) and EAT thickness (5.3 ± 2.3 vs 6.6 ± 2.6 mm, p = .001) were higher in the prolonged QTc group. Serum potassium (K) level was lesser in the prolonged QTc group (4.2 ± 0.39 vs 4.1 ± 0.4 mmol/mL, p = .005). Multivariate Cox regression analysis revealed that EAT thickness [OR = 1.227, 95% CI: 1.081-1.393, p = .002] and serum K level [OR = 0.348, 95% CI: 0.157-0.772, p = .009] predicted the prolonged QTc interval, independently. Conclusion: EAT thickness predicted prolonged QTc interval in patients with arterial hypertension. Patients with higher amount of EAT should be followed by closely monitoring to prevent arrhythmic events that may develop in the future. In addition, medications that have a potential effect on QTc interval prolongation may be carefully used in patients with higher EAT thickness.

Inflammation and adiposity: new frontiers in atrial fibrillation

The aetiology of atrial fibrillation (AF) remains poorly understood, despite its growing prevalence and associated morbidity, mortality, and healthcare costs. Obesity is implicated in myriad different disease processes and is now recognized a major risk factor in the pathogenesis of AF. Moreover, the role of distinct adipose tissue depots is a matter of intense scientific interest with the depot directly surrounding the heart—epicardial adipose tissue (EAT) appearing to have the greatest correlation with AF presence and severity. Similarly, inflammation is implicated in the pathophysiology of AF with EAT thought to act as a local depot of inflammatory mediators. These can easily diffuse into atrial tissue with the potential to alter its structural and electrical properties. Various meta-analyses have indicated that EAT size is an independent risk factor for AF with adipose tissue expansion being inevitably associated with a local inflammatory process. Here, we first briefly review adipose tissue anatomy and physiology then move on to the epidemiological data correlating EAT, inflammation, and AF. We focus particularly on discussing the mechanistic basis of how EAT inflammation may precipitate and maintain AF. Finally, we review how EAT can be utilized to help in the clinical management of AF patients and discuss future avenues for research.

Relation of cardiac adipose tissue to coronary calcification and myocardial microvascular function in type 1 and type 2 diabetes

Background

Cardiac adipose tissue may have local paracrine effects on epicardial arteries and the underlying myocardium, promoting calcification and affecting myocardial microcirculation. We explored whether the total amount of cardiac adipose tissue was associated with coronary artery calcium score (CAC) and myocardial flow reserve in persons with type 1 or type 2 diabetes and healthy controls.

Methods

We studied three groups: (1) 30 controls, (2) 60 persons with type 1 diabetes and (3) 60 persons with type 2 diabetes. The three groups were matched for sex and age. The three groups derived from retrospective analysis of two clinical studies. All underwent cardiac ⁸²Rb positron emission tomography/computed tomography (PET/CT) scanning. Cardiac adipose tissue volume (the sum of epicardial and pericardial fat), CAC, and myocardial flow reserve (ratio of pharmacological stress flow and rest flow) were evaluated using semiautomatic software. We applied linear regression to assess the association between cardiac adipose tissue, CAC and myocardial flow reserve.

Results

Mean (SD) cardiac adipose tissue volume was 99 (61) mL in the control group, 106 (78) mL in the type 1 diabetes group and 228 (97) mL in the type 2 diabetes group. Cardiac adipose tissue was positively associated with body mass index in all three groups (p ≤ 0.02). In the controls, cardiac adipose tissue was positively associated with CAC score (p = 0.008) and negatively associated with myocardial flow reserve (p = 0.005). However, cardiac adipose tissue was not associated with CAC or myocardial flow reserve in the groups including persons with type 1 or type 2 diabetes (p ≥ 0.50).

Conclusions

In contrast to what was found in healthy controls, we could not establish a relation between cardiac adipose tissue and coronary calcification or myocardial microvascular function in person with type 1 or type 2 diabetes. The role of cardiac adipose tissue in cardiovascular disease in diabetes remains unclear.

Effect of Echocardiographic Epicardial Adipose Tissue Thickness on Success Rates of Premature Ventricular Contraction Ablation

Background:

Idiopathic premature ventricular contractions are frequently detected ventricular arrhythmias, and radiofrequency ablation is an effectively treatment for improving symptoms and eliminating premature ventricular contractions. Studies have reported a relationship between an elevated epicardial adipose tissue thickness and myocardial structural pathologies. However, the association between epicardial adipose tissue thickness and success rates of premature ventricular contraction ablation has not yet been investigated.

Aims:

To assess the relationship between epicardial adipose tissue thickness and success rates of premature ventricular contraction ablation.

Study Design:

Retrospective case-control study.

Methods:

This study enrolled a total of 106 consecutive patients who have had a high premature ventricular contraction burden of >10,000/24-h assessed using ambulatory Holter monitorization and underwent catheter ablation. A frequency of premature ventricular contractions of more than 10,000/day was defined as frequent premature ventricular contraction. Epicardial adipose tissue thickness was measured using 2D transthoracic echocardiography. A successful ablation was defined as >80% decrease in pre-procedural premature ventricular contraction attacks with the same morphology during 24-h Holter monitorization after a 1-month follow-up visit from an ablation procedure.

Results:

Successful premature ventricular contraction ablation was achieved in 87 (82.1%) patients. Epicardial adipose tissue thickness was significantly higher in patients with unsuccessful ablation (p<0.001). Procedure time, total fluoroscopy time, and radiofrequency ablation time were statistically higher in the unsuccessful group (p<0.001). Stepwise multivariate logistic regression analysis showed that epicardial adipose tissue thickness and pseudo-delta wave time were independently associated with procedural success (both p values <0.001). In the receiver-operating curve analysis, epicardial adipose tissue thickness was found to be an important predictor for procedural success (area under the receiver-operating characteristic curve= 0.85, p=0.001), with a cutoff value of 7.7 mm, a sensitivity of 92%, and a specificity of 68%.

Conclusion:

Epicardial adipose tissue thickness is higher in patients with premature ventricular contraction ablation failure, which may be indicative of procedural success.