The presence of fragmented QRS is associated with increased epicardial adipose tissue and subclinical myocardial dysfunction in healthy individuals

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.

The epicardial fat thickness is associated with fragmented QRS in patients with newly diagnosed metabolic syndrome

OBJECTIVE

The metabolic syndrome involves both metabolic and cardiovascular risk factors and is associated with cardiovascular mortality. Epicardial fat tissue plays a crucial role in deleterious effects of metabolic syndrome on the heart, including myocardial fibrosis. The fragmented QRS reflects heterogeneous depolarization of the myocardium and occurs as a result of fibrosis. Thus, we aimed to investigate whether there is an association between fragmented QRS and epicardial fat tissue in patients with metabolic syndrome.

METHODS

This study enrolled 140 metabolic syndrome patients, of whom 35 patients with fragmented QRS (+) and 105 patients with fragmented QRS (-). The two groups were compared with respect to clinical, laboratory, electrocardiographic, and echocardiographic indexes.

RESULTS

Fragmented QRS (+) patients had higher waist circumference, red cell distribution width, creatinine, left ventricular end-systolic diameter, left atrium diameter, septal a velocity, QRS duration, and epicardial fat tissue compared with fragmented QRS (-) patients. Waist circumference, red cell distribution width, QRS duration, left ventricular end-systolic diameter, left atrium diameter, septal a velocity, and epicardial fat tissue were significantly associated with the presence of fragmented QRS. The QRS duration and epicardial fat tissue were independently associated with the presence of fragmented QRS on surface electrocardiographic in metabolic syndrome patients.

CONCLUSIONS

Epicardial fat tissue and QRS duration were independently associated with the presence of fragmented QRS. Basic echocardiographic and electrocardiographic parameters might be used for the risk stratification in metabolic syndrome patients.

Modulation of Cardiac Arrhythmogenesis by Epicardial Adipose Tissue: JACC State-of-the-Art Review

Obesity is a significant risk factor for arrhythmic cardiovascular death. Interactions between epicardial adipose tissue (EAT) and myocytes are thought to play a key role in the development of arrhythmias. In this review, the authors investigate the influence of EAT on arrhythmogenesis. First, they summarize electrocardiographic evidence showing the association between increased EAT volume and atrial and ventricular conduction delay. Second, they detail the structural cross talk between EAT and the heart and its arrhythmogenicity. Adipose tissue infiltration within the myocardium constitutes an anatomical obstacle to cardiac excitation. It causes activation delay and increases the risk of arrhythmias. Intercellular electrical coupling between cardiomyocytes and EAT can further slow conduction and increase the risk of block, favoring re-entry and arrhythmias. Finally, EAT secretes multiple substances that influence cardiomyocyte electrophysiology either by modulating ion currents and electrical coupling or by stimulating fibrosis. Thus, structural and paracrine cross talk between EAT and cardiomyocytes facilitates arrhythmias.

Fragmented QRS as an early predictor of left ventricular systolic dysfunction in healthy individuals: a nested case-control study in the era of speckle tracking echocardiography

BACKGROUND

Several studies addressed the association between fragmented QRS (fQRS) on 12-lead EKG and left ventricular (LV) dysfunction in patients with a variety of cardiovascular disorders. We tested such association in healthy individuals.

METHODS

Out of 500 healthy participants without -overt cardiovascular disease from the Shiraz Heart Study cohort, we identified 20 subjects with fQRS (cases) and 20 peers without fQRS (controls). Global LV longitudinal strain (GLS) was measured by speckle tracking echocardiography in the two groups. Comparison was made between case and control groups by using chi-square or independent sample t-test or ANOVA.

RESULTS

Age, gender, ejection fraction, LV volume and dimensions did not differ between the case and the control groups. Overall, 14 subjects out of 40 had reduced GLS (≤20%) and 10 of them (25%) had fQRS. GLS was significantly lower in the group with fQRS than in the control group (19.9 ± 1.8 vs 21.4 ± 1.6; p = 0.009).

CONCLUSIONS

Healthy subjects with fQRS present regional LV systolic dysfunction, assessed by GLS, in the presence of a normal ejection fraction. These data suggest that fQRS may be a promising tool to identify apparently healthy subjects with regional LV systolic dysfunction.

Fragmented QRS and subclinical left ventricular dysfunction in individuals with preserved ejection fraction: A speckle-tracking echocardiographic study

INTRODUCTION

Fragmented QRS (fQRS) complex on routine 12-lead electrocardiogram (ECG) predicts adverse outcomes in patients with cardiovascular diseases. In addition, it has been found to be associated with subclinical myocardial dysfunction in chronic diseases. We sought to investigate the relationship between the presence of fQRS with the myocardial functions in individuals free from known systemic cardiovascular diseases.

METHODS

In a case-control study, we evaluated normal individuals from March 2017 to February 2018. All participants underwent a 2-dimensional transthoracic echocardiographic examination using tissue Doppler imaging (TDI) and speckle-tracking echocardiography. In addition, all participants were examined using a 12-lead surface ECG, and patients with fQRS and a group of age- and sex-matched controls without fQRS were enrolled in our study.

RESULTS

The patients' mean age was 40.3 ± 10.7 and 35.4 ± 11.2 years in fQRS-positive and fQRS-negative groups, respectively (P = .110). Patients with fQRS had significantly lower values of apical left ventricular global longitudinal strain (LV GLS) in 2-chamber (16.9 ± 2.5 vs. 20.5 ± 3.3, P < .001), 4-chamber (16.9 ± 3.4 vs. 20.1 ± 3, P = .001), LAX views (17.7 ± 2.8 vs. 20.8 ± 3.5, P = .001), and averaged LV GLS (17 ± 2.6 vs. 20.4 ± 2.7, P < .001) values compared to patients without fQRS. In a multivariate analysis, averaged LV GLS and smoking history were independent predictors for positive fQRS.

CONCLUSION

The presence of fQRS on 12-lead ECG in healthy population was associated with lower values of LV GLS compared to normal individuals without fQRS.