FFAs and QT intervals in obese women with visceral adiposity: effects of sustained weight loss over 1 year

Electrocardiographic markers of ventricular repolarization in the obese population: A descriptive review

Obesity is a global epidemiological problem that significantly contributes to the development of cardiovascular diseases. It is a proven factor for an increased risk of overall mortality and the occurrence of sudden cardiac death (SCD). The disease is accompanied by a structural and functional myocardium remodeling, which often results in ventricular repolarization abnormalities and contributes to the triggering of life-threatening arrhythmias. This heightened state of readiness for proarrhythmia is the cause of the sudden cardiac deaths which are recorded in this group of patients and which often constitute the first manifestation of ongoing cardiac pathology. One of the reasons for these arrhythmias may be abnormalities of ventricular muscle repolarization. In this descriptive review, we demonstrate electrocardiographic markers of ventricular repolarization (J point, QT/QTc/QTc-d, JT/JTc/JTc-d, ST segment, T wave and Tp-e/Tp-ed/Tp-e/QT), analyze their abnormalities in the obese population, and discuss their changes after weight loss.

Ventricular conduction improvement after pericardial fat reduction triggered by rapid weight loss in subjects with obesity undergoing bariatric surgery

BACKGROUND

Obesity is considered a major cardiovascular risk factor. The excess of pericardial fat (PF) in patients with obesity has been associated with a variety of electrocardiographic alterations. In previous studies, we demonstrated that rapid weight loss and bariatric interventions result in decreased PF.

OBJECTIVES

The aim of this study is to report the changes in PF after bariatric surgery and its effect on ventricular conduction.

SETTING

US hospital, academic institution.

METHODS

A linear measurement of PF thickness on computed tomography scans was obtained for 81 patients, as well as a retrospective review of electrocardiographic changes before and after bariatric surgery. We compared the changes in PF thickness and electrocardiographic components before and after procedures. Common demographics and co-morbidities were collected along with lipid profiles preoperative and postoperative.

RESULTS

A total of 81 patients had electrocardiograms done before and 1 year after bariatric surgery. Females comprised 67.9% (n = 55), and the average age for our population was 55.07 ± 14.17 years. Pericardial fat thickness before surgery was 5.6 ± 1.84 and 4.5 ± 1.62 mm after surgery (P = .0001). Ventricular conduction (QT and QT corrected [QTc] intervals) showed a significant improvement from 438.7 + 29 before to 426.8 + 25.3 after bariatric surgery (P = .006). We found a statistically significant association between the decrease in PF and the decrease in QTc intervals (P = .002).

CONCLUSION

Obesity is a risk factor for arrhythmias and sudden cardiac death. Bariatric surgery and its effect on PF produce an improvement in ventricular conduction, which may reduce the ventricular electrical instability in patients with obesity.

The negative effects of obesity on heart, especially the electrophysiology of the heart

Obesity is associated with ventricular arrhythmia and sudden cardiac death. Numerous studies have shown that obesity may have effects on the heart by affecting the ventricular re-polarisation (VR). As an effective detection method for VR the measurement of the QT interval has been extensively studied in obese patients (OP). This review aims to investigate the relationship between obesity and obesity-related diseases; including diabetes, hypertension and cardiovascular diseases (CVD). This review compares the advantages and disadvantages of different QT interval measurement methods, as well as explores the possible mechanisms of obesity leading to heart disease. Finally, it also reviews the feasibility of various weight loss methods to reverse the risk of obesity leading to heart disease is discussed.

Different body parts' fat mass and corrected QT interval on the electrocardiogram: The Fasa PERSIAN Cohort Study

Background

Previous studies suggested that obesity and fat mass are associated with QT interval prolongation, but the role of different body parts' fat mass is unclear. The associations between total and regional fat mass (FM) and corrected QT interval (QTc) were investigated for the first time in this study.

Methods

In this sub-analysis of Fasa PERSIAN cohort Study data, 3217 subjects aged 35–70 entered our study. Body fat mass was assessed by bioelectrical impedance analysis and QTc interval calculated by the QT interval measured by Cardiax^® software from ECGs and Bazett’s formula. Uni- and multi-variable linear and logistic regression was performed in IBM SPSS Statistics v23.

Results

In males, the fat mass to fat-free mass (FM/FFM) ratio in the trunk, arms, total body, and legs were significantly higher in the prolonged QTc group (QTc > 450 ms). Trunk (B = 0.148), total (B = 0.137), arms (B = 0.124), legs (B = 0.107) fat mass index (FMI) showed significant positive relationship with continuous QTc (P-value < 0.001). Also, just the fat-free mass index of legs had significant positive associations with QTc interval (P-value < 0.05). Surprisingly, in females, the mean of FM/FFM ratio in trunk and legs in the normal QTc group had higher values than the prolonged QTc group (QTc > 470 ms). Also, none of the body composition variables had a significant correlation with continuous QTc.

Conclusion

Our study suggested that FMI ratios in the trunk, total body, arms, and legs were positively associated with QTc interval in males, respectively, from a higher to a lower beta-coefficient. Such associations were not seen in females. Our study implies that body fat mass may be an independent risk factor for higher QTc interval and, consequently, more cardiovascular events that should be investigated.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-02095-2.

Effects of Bariatric Surgery on Heart Rhythm Disorders: a Systematic Review and Meta-Analysis

The aim of this systematic review is to provide an overview of the literature on the effects of bariatric surgery on obesity-associated electrocardiogram (ECG) abnormalities and cardiac arrhythmias. Fourteen studies were included with a methodological quality ranging from poor to good. Majority of the studies showed a significant decrease of QT interval and related measures after bariatric surgery. Seven studies were included in the meta-analysis on effects of bariatric surgery on QTc interval and a significant decrease in QTc interval of - 33.6 ms, 95%CI [- 49.8 to - 17.4] was seen. Bariatric surgery results in significant decrease in QTc interval and P-wave dispersion, i.e., a normalization of initial pathology. The effects on atrial fibrillation are conflicting and not yet fully understood.

Lipid mechanisms in hallmarks of cancer

Excess adiposity is a risk factor for several cancer types. This is likely due to complex mechanisms including alterations in the lipid milieu that plays a pivotal role in multiple aspects of carcinogenesis. Here we consider the direct role of lipids in regulating well-known hallmarks of cancer. Furthermore, we suggest that obesity-associated remodelling of membranes and organelles drives cancer cell proliferation and invasion. Identification of cancer-related lipid-mediated mechanisms amongst the broad metabolic disturbances due to excess adiposity is central to the identification of novel and more efficacious prevention and intervention strategies.

Association of Adiponectin with Lung Function Impairment and Disease Severity in Chronic Obstructive Pulmonary Disease

Context:

Chronic obstructive pulmonary disease (COPD) is not only restricted to the pulmonary inflammation and airway obstruction but is also associated with comorbidities, which affect the therapeutic intervention and the quality of life and survival. Markers that can predict the systemic inflammation and a decline in the pulmonary function are of scientific interest. Adiponectin (APN) appears to be one such biomarker and can be used as a potential indicator of severity and response to treatment in patients of COPD.

Aims:

The study aims to find out the role of APN as a marker of inflammation in the pathogenesis of COPD and explore its relationship with the severity of the disease.

Settings and Design:

This was a cross-sectional study.

Subjects and Methods:

The study group consisted of 60 patients of COPD, which included 30 males admitted with acute exacerbation of COPD (AECOPD) and 30 males with stable COPD. The study group was compared with 30 healthy, age-matched males. APN was estimated by commercially available ELISA kits. Pulmonary function tests were performed on all cases and controls using standardized protocols on SPIROLAB III.

Statistical Analysis Used:

Statistical analysis was performed using Student's t-test and Pearson's correlation coefficient.

Results:

The levels of APN were found to be significantly higher in patients with COPD as compared to the controls and the levels increased with the severity of the disease were 16.10 ± 4.97 ng/ml and 11.43 ± 4.22 ng/ml, respectively, in AECOPD and COPD. A significant positive correlation was found between the levels of APN and interleukin (IL)-8 in patients of COPD, while the levels correlated negatively with percentage of forced expiratory volume in 1 s (FEV1%).

Conclusions:

The results reveal that APN is associated with the inflammatory process of COPD as suggested by its significant inverse relationship with FEV1% and positive correlation with a marker of inflammation such as IL-8. It can thus be used as a biomarker for disease severity and progression in patients of COPD, therefore aiding in risk stratification and therapeutic intervention.

Comparison of High-Protein, Intermittent Fasting Low-Calorie Diet and Heart Healthy Diet for Vascular Health of the Obese

AIM

It has been debated whether different diets are more or less effective in long-term weight loss success and cardiovascular disease prevention among men and women. To further explore these questions, the present study evaluated the combined effects of a high-protein, intermittent fasting, low-calorie diet plan compared with a heart healthy diet plan during weight loss, and weight loss maintenance on blood lipids and vascular compliance of obese individuals.

METHODS

The experiment involved 40 obese adults (men, n = 21; women, n = 19) and was divided into two phases: (a) 12-week high-protein, intermittent fasting, low-calorie weight loss diet comparing men and women (Phase 1) and (b) a 1-year weight maintenance phase comparing high-protein, intermittent fasting with a heart healthy diet (Phase 2). Body weight, body mass index (BMI), blood lipids, and arterial compliance outcomes were assessed at weeks 1 (baseline control), 12 (weight loss), and 64 (12 + 52 week; weight loss maintenance).

RESULTS

At the end of weight loss intervention, concomitant reductions in body weight, BMI and blood lipids were observed, as well as enhanced arterial compliance. No sex-specific differences in responses were observed. During phase 2, the high-protein, intermittent fasting group demonstrated a trend for less regain in BMI, low-density lipoprotein (LDL), and aortic pulse wave velocity than the heart healthy group.

CONCLUSION

Our results suggest that a high-protein, intermittent fasting and low-calorie diet is associated with similar reductions in BMI and blood lipids in obese men and women. This diet also demonstrated an advantage in minimizing weight regain as well as enhancing arterial compliance as compared to a heart healthy diet after 1 year.

Effect of obesity and weight loss on ventricular repolarization: a systematic review and meta-analysis

We performed a systematic review and meta-analysis of the effects of obesity ± overweight and weight loss on the corrected QT interval (QTc) and QT or QTc dispersion (indices of ventricular repolarization). Mean difference for both QTc and QT or QTc dispersion with 95% confidence intervals (CIs) was calculated comparing obese ± overweight subjects and normal weight controls and QTc and QT or QTc dispersion before and after weight loss from diet ± exercise or bariatric surgery. A total of 22 studies fulfilled the selection criteria. Compared with normal weight controls, there was a significantly longer QTc in obese ± overweight subjects (mean difference of 21.74 msec, 95% CI: 18.76 to 22.32) and significantly longer QT or QTc dispersion (mean difference of 15.17 msec, 95% CI: 13.59 to 16.74). Weight loss was associated with a significant decrease in QTc (mean difference -25.77 msec, 95% CI: -28.33-23.21) and QT or QTc dispersion (mean difference of -13.46 msec, 95% CI: -15.60 to -11.32 in obese ± overweight subjects. Thus, obesity ± overweight is associated with significant prolongation of QTc and QT or QTC dispersion. Weight loss in obese ± overweight subjects produces significant decreases in these variables. © 2016 World Obesity.

Metabolic syndrome is associated with a poor outcome in patients affected by outflow tract premature ventricular contractions treated by catheter ablation

Background

The purpose of this study was to investigate the impact of metabolic syndrome (MS) on outcome of catheter ablation (CA) for treatment of frequent premature ventricular contraction beats (PVCs) originating from right ventricular outflow tract (RVOT), left ventricular outflow tract (LVOT) or coronary cusps (CUSPs), in patients with normal ventricular systolic function and absence of cardiac structural disease.

Methods

In this multicentre prospective study we evaluated 90 patients with frequent PVCs originating from RVOT (n = 68), LVOT (n = 19) or CUSPs (n = 3), treated with CA. According to baseline diagnosis they were divided in patients with MS (n = 24) or without MS (n = 66). The study endpoint was a composite of recurrence of acute or delayed outflow tract ventricular arrhythmia: acute spontaneous or inducible outflow tract ventricular arrhythmia recurrence or recurrence of outflow tract PVCs in holter monitoring at follow up.

Results

Patients with MS compared to patients without MS showed a higher acute post-procedural recurrence of outflow tract PVCs (n = 8, 66.6%, vs. n = 6, 9.0%, p = 0.005). At a mean follow up of 35 (17-43) months survival free of recurrence of outflow tract PVCs was lower in patients with baseline MS compared to patients without MS diagnosis (log-rank test, p < 0.001). In cox regression analysis, only MS was independently associated with study endpoint (HR = 9.655 , 95% CI 3.000-31.0.68 , p < 0.001).

Conclusions

MS is associated with a higher recurrence rate of outflow tract PVCs after CA in patients without structural heart disease.

Adiposopathy: how do diet, exercise and weight loss drug therapies improve metabolic disease in overweight patients?

An increase in bodyweight is generally associated with an increased risk of excessive fat-related metabolic diseases (EFRMD), including Type 2 diabetes mellitus, hypertension and dyslipidemia. However, not all patients who are overweight have EFRMD, and not all patients with EFRMD are significantly overweight. The adipocentric paradigm provides the basis for a unifying, pathophysiological process whereby fat gain in susceptible patients leads to fat dysfunction ('sick fat'), and wherein pathological abnormalities in fat function (adiposopathy) are more directly related to the onset of EFRMD than increases in fat mass (adiposity) alone. But just as worsening fat function worsens EFRMD, improved fat function improves EFRMD. Peroxisome proliferator-activated receptor-gamma agonists increase the recruitment, proliferation and differentiation of preadipocytes ('healthy fat') and cause apoptosis of hypertrophic and dysfunctional (including visceral) adipocytes resulting in improved fat function and improved metabolic parameters associated with EFRMD. Weight loss interventions, such as a hypocaloric diet and physical exercise, in addition to agents such as orlistat, sibutramine and cannabinoid receptor antagonists, may have favorable effects upon fat storage (lipogenesis and fat distribution), nutrient metabolism (such as free fatty acids), favorable effects upon adipose tissue factors involved in metabolic processes and inflammation, and enhanced 'cross-talk' with other major organ systems. In some cases, weight loss therapeutic agents may even affect metabolic parameters and adipocyte function independently of weight loss alone, suggesting that the benefit of these agents in improving EFRMD may go beyond their efficacy in weight reduction. This review describes how adiposopathy interventions may affect fat function, and thus improve EFRMD.

β-adrenergic receptor responsiveness in aging heart and clinical implications

Elderly healthy individuals have a reduced exercise tolerance and a decreased left ventricle inotropic reserve related to increased vascular afterload, arterial-ventricular load mismatching, physical deconditioning and impaired autonomic regulation (the so called "β-adrenergic desensitization"). Adrenergic responsiveness is altered with aging and the age-related changes are limited to the β-adrenergic receptor density reduction and to the β-adrenoceptor-G-protein(s)-adenylyl cyclase system abnormalities, while the type and level of abnormalities change with species and tissues. Epidemiological studies have shown an high incidence and prevalence of heart failure in the elderly and a great body of evidence correlate the changes of β-adrenergic system with heart failure pathogenesis. In particular it is well known that: (a) levels of cathecolamines are directly correlated with mortality and functional status in heart failure, (b) β1-adrenergic receptor subtype is down-regulated in heart failure, (c) heart failure-dependent cardiac adrenergic responsiveness reduction is related to changes in G proteins activity. In this review we focus on the cardiovascular β-adrenergic changes involvement in the aging process and on similarities and differences between aging heart and heart failure.

Adrenergic signaling and oxidative stress: a role for sirtuins?

The adrenergic system plays a central role in stress signaling and stress is often associated with increased production of ROS. However, ROS overproduction generates oxidative stress, that occurs in response to several stressors. β-adrenergic signaling is markedly attenuated in conditions such as heart failure, with downregulation and desensitization of the receptors and their uncoupling from adenylyl cyclase. Transgenic activation of β2-adrenoceptor leads to elevation of NADPH oxidase activity, with greater ROS production and p38MAPK phosphorylation. Inhibition of NADPH oxidase or ROS significantly reduced the p38MAPK signaling cascade. Chronic β2-adrenoceptor activation is associated with greater cardiac dilatation and dysfunction, augmented pro-inflammatory and profibrotic signaling, while antioxidant treatment protected hearts against these abnormalities, indicating ROS production to be central to the detrimental signaling of β2-adrenoceptors. It has been demonstrated that sirtuins are involved in modulating the cellular stress response directly by deacetylation of some factors. Sirt1 increases cellular stress resistance, by an increased insulin sensitivity, a decreased circulating free fatty acids and insulin-like growth factor (IGF-1), an increased activity of AMPK, increased activity of PGC-1a, and increased mitochondrial number. Sirt1 acts by involving signaling molecules such P-I-3-kinase-Akt, MAPK and p38-MAPK-β. βAR stimulation antagonizes the protective effect of the AKT pathway through inhibiting induction of Hif-1α and Sirt1 genes, key elements in cell survival. More studies are needed to better clarify the involvement of sirtuins in the β-adrenergic response and, overall, to better define the mechanisms by which tools such as exercise training are able to counteract the oxidative stress, by both activation of sirtuins and inhibition of GRK2 in many cardiovascular conditions and can be used to prevent or treat diseases such as heart failure.

Adrenergic signaling and oxidative stress: a role for sirtuins?

The adrenergic system plays a central role in stress signaling and stress is often associated with increased production of ROS. However, ROS overproduction generates oxidative stress, that occurs in response to several stressors. β-adrenergic signaling is markedly attenuated in conditions such as heart failure, with downregulation and desensitization of the receptors and their uncoupling from adenylyl cyclase. Transgenic activation of β2-adrenoceptor leads to elevation of NADPH oxidase activity, with greater ROS production and p38MAPK phosphorylation. Inhibition of NADPH oxidase or ROS significantly reduced the p38MAPK signaling cascade. Chronic β2-adrenoceptor activation is associated with greater cardiac dilatation and dysfunction, augmented pro-inflammatory and profibrotic signaling, while antioxidant treatment protected hearts against these abnormalities, indicating ROS production to be central to the detrimental signaling of β2-adrenoceptors. It has been demonstrated that sirtuins are involved in modulating the cellular stress response directly by deacetylation of some factors. Sirt1 increases cellular stress resistance, by an increased insulin sensitivity, a decreased circulating free fatty acids and insulin-like growth factor (IGF-1), an increased activity of AMPK, increased activity of PGC-1a, and increased mitochondrial number. Sirt1 acts by involving signaling molecules such P-I-3-kinase-Akt, MAPK and p38-MAPK-β. βAR stimulation antagonizes the protective effect of the AKT pathway through inhibiting induction of Hif-1α and Sirt1 genes, key elements in cell survival. More studies are needed to better clarify the involvement of sirtuins in the β-adrenergic response and, overall, to better define the mechanisms by which tools such as exercise training are able to counteract the oxidative stress, by both activation of sirtuins and inhibition of GRK2 in many cardiovascular conditions and can be used to prevent or treat diseases such as heart failure.

Metabolic syndrome remodels electrical activity of the sinoatrial node and produces arrhythmias in rats

In the last ten years, the incidences of metabolic syndrome and supraventricular arrhythmias have greatly increased. The metabolic syndrome is a cluster of alterations, which include obesity, hypertension, hypertriglyceridemia, glucose intolerance and insulin resistance, that increase the risk of developing, among others, atrial and nodal arrhythmias.

The aim of this study is to demonstrate that metabolic syndrome induces electrical remodeling of the sinus node and produces arrhythmias. We induced metabolic syndrome in 2-month-old male Wistar rats by administering 20% sucrose in the drinking water. Eight weeks later, the rats were anesthetized and the electrocardiogram was recorded, revealing the presence of arrhythmias only in treated rats. Using conventional microelectrode and voltage clamp techniques, we analyzed the electrical activity of the sinoatrial node.

We observed that in the sinoatrial node of “metabolic syndrome rats”, compared to controls, the spontaneous firing of all cells decreased, while the slope of the diastolic depolarization increased only in latent pacemaker cells. Accordingly, the pacemaker currents I_f and I_st increased. Furthermore, histological analysis showed a large amount of fat surrounding nodal cardiomyocytes and a rise in the sympathetic innervation. Finally, Poincaré plot denoted irregularity in the R-R and P-P ECG intervals, in agreement with the variability of nodal firing potential recorded in metabolic syndrome rats.

We conclude that metabolic syndrome produces a dysfunction SA node by disrupting normal architecture and the electrical activity, which could explain the onset of arrhythmias in rats.

Adiponectin: an attractive marker for metabolic disorders in Chronic Obstructive Pulmonary Disease (COPD)

Chronic Obstructive Pulmonary Disease (COPD) is a chronic inflammatory lung disease which may be complicated by development of co-morbidities including metabolic disorders. Metabolic disorders commonly associated with this disease contribute to lung function impairment and mortality. Systemic inflammation appears to be a major factor linking COPD to metabolic alterations. Adipose tissue seems to interfere with systemic inflammation in COPD patients by producing a large number of proteins, known as “adipokines”, involved in various processes such as metabolism, immunity and inflammation. There is evidence that adiponectin is an important modulator of inflammatory processes implicated in airway pathophysiology. Increased serum levels of adiponectin and expression of its receptors on lung tissues of COPD patients have recently highlighted the importance of the adiponectin pathway in this disease. Further, in vitro studies have demonstrated an anti-inflammatory activity for this adipokine at the level of lung epithelium. This review focuses on mechanisms by which adiponectin is implicated in linking COPD with metabolic disorders.

Potential mechanisms linking atherosclerosis and increased cardiovascular risk in COPD: focus on Sirtuins

The development of atherosclerosis is a multi-step process, at least in part controlled by the vascular endothelium function. Observations in humans and experimental models of atherosclerosis have identified monocyte recruitment as an early event in atherogenesis. Chronic inflammation is associated with ageing and its related diseases (e.g., atherosclerosis and chronic obstructive pulmonary disease). Recently it has been discovered that Sirtuins (NAD⁺-dependent deacetylases) represent a pivotal regulator of longevity and health. They appear to have a prominent role in vascular biology and regulate aspects of age-dependent atherosclerosis. Many studies demonstrate that SIRT1 exhibits anti-inflammatory properties in vitro (e.g., fatty acid-induced inflammation), in vivo (e.g., atherosclerosis, sustainment of normal immune function in knock-out mice) and in clinical studies (e.g., patients with chronic obstructive pulmonary disease). Because of a significant reduction of SIRT1 in rodent lungs exposed to cigarette smoke and in lungs of patients with chronic obstructive pulmonary disease (COPD), activation of SIRT1 may be a potential target for chronic obstructive pulmonary disease therapy. We review the inflammatory mechanisms involved in COPD-CVD coexistence and the potential role of SIRT1 in the regulation of these systems.

Relation of left ventricular mass to QTc in normotensive severely obese patients

Prolongation of the corrected QT interval (QTc) has been described in obese subjects. This study assesses the relation of left ventricular (LV) mass to QTc in normotensive severely obese subjects. Fifty normotensive patients whose BMI was ≥40 kg/m(2) (mean age: 38 ± 7 years) were studied. QTc was derived using Bazett's formula. LV mass was calculated using the formula of Devereux et al. and was indexed to height(2.7). Mean QTc was 428.8 ± 19.0 ms and was significantly longer in those with than in those without LV hypertrophy (P < 0.01) QTc correlated positively and significantly with BMI (r = 0.392, P < 0.025), LV mass/height(2.7) (r = 0.793, P < 0.0005), systolic blood pressure (r = 0.742, P < 0.001), LV end - systolic wall stress (r = 0.746, P < 0.001) and LV internal dimension in diastole (r = 0.788, P < 0.0005). Among five variables tested, LV mass/height(2.7) was identified as the sole predictor of QTc by multivariate analysis. In conclusion, LV mass and loading conditions that may affect LV mass are important determinants of QTc in normotensive severely obese subjects.

Novel electrocardiographic parameters of altered repolarization in uncomplicated overweight and obesity

In addition to well-known electrocardiographic measurements, as QT, QT dispersion, and QT apex dispersion, new parameters such as Tpeak-Tend, Tpeak-Tend dispersion, and Tpeak-Tend/QT ratio have been recently introduced as indexes of increased arrhythmic risk. The aim of the present study was to test, in overweight and obese subjects not affected by conditions of comorbidity, the aforementioned markers of ventricular repolarization. We studied 60 athletic subjects with normal body weight (21 females and 39 males, BMI between 19 and 24, mean BMI 22.0 ± 2.0 kg/m(2), aged 14-64 years, mean age 32 ± 13.59) and 60 sedentary and overweight/obese subjects (34 overweight and 26 obese, 22 females, and 38 males, BMI between 26 and 55, mean BMI 30.7 ± 5.7 kg/m(2), aged 14-64, mean age 38 ± 14.49). Each subject underwent anthropometric measurements and a 12-lead electrocardiogram, from which the following different parameters were calculated: QT, corrected QT, QT dispersion, QT apex dispersion, Tpeak-Tend, Tpeak-Tend dispersion and Tpeak-Tend/QT ratio were calculated. The aforementioned repolarization markers resulted, respectively: 340.2 ± 25.1, 373.8 ± 25.9, 29 ± 16.2, 23.5 ± 14.6, 87.3 ± 12.8, 26.5 ± 16.8, and 0.22 ± 0.03 ms in control subjects and 362.5 ± 28.5, 397.4 ± 35.4, 34.5 ± 16.8, 30.7 ± 16.3, 90.5 ± 15.2, 27 ± 17.1, and 0.22 ± 0.04 ms in overweight/obese subjects. Neither uncomplicated obesity nor overweight were associated with a statistically significant difference in QT dispersion, QT apex dispersion, Tpeak-Tend, Tpeak-Tend dispersion, and Tpeak-Tend/QT ratio; QT and corrected QT were the only parameters that showed statistically significant variations between normal weight and overweight/obese subjects.

Factors affecting the degree of QT prolongation with drug challenge in a large cohort of normal volunteers

BACKGROUND

The degree of QT prolongation by drug is highly variable and related to risk for polymorphic ventricular tachycardia due to drugs.

OBJECTIVE

The purpose of this study was to determine factors that affect the degree of QT prolongation by drugs.

METHODS

QT and QTc were measured before and after administration of the QT-prolonging drug ibutilide in 253 normal volunteers aged 18 to 40 years. Drug effect on QTc prolongation was defined as ΔQTc = QTc after drug minus QTc before drug.

RESULTS

Ibutilide prolonged QT from 396 ± 31 ms to 418 ± 39 ms (P <.001) and QTc from 406 ± 15 ms to 446 ± 33 ms (P <.001). ΔQTc did not correlate with baseline QTc (Pearson correlation 0.016, P = .8). Postdrug QTc was correlated weakly with predrug QTc (Pearson correlation 0.484, P <.001), and strongly with ΔQTc (Pearson correlation 0.882, P <.001). ΔQTc was identical for men and women (39 ± 29 ms vs 39 ± 27 ms, P = .9) but displayed significant differences among body mass index categories (P <.001). Overweight (48 ± 27 ms) and obese (61 ± 31 ms) subjects had significantly more QT prolongation by drug than normal (31 ± 25 ms) or underweight (24 ± 12 ms) subjects.

CONCLUSION

QT prolongation by ibutilide does not correlate to baseline QTc and does not differ between men and women. Overweight and obese subjects have greater drug effect on QTc than subjects with normal or low body mass index. These findings have implications for drug-induced long QT syndrome.

The myth of QT shortening by weight loss and physical training in obese subjects with coronary heart disease

This study aims to describe the changes that a period of low-calorie diet and physical training determines in heart rate and in corrected QT (QTc) interval in obese patients with coronary heart disease (CHD) and to verify whether it is effective in shortening the QT interval using three different methods for QT correction. Two hundred and seventy obese white patients (162 males--60%) affected with stable CHD and treated with β-blockers were retrospectively studied in the setting of a program aimed at losing weight through training (aerobic activity + strength exercise) and diet (80% of estimated resting energy expenditure). Age was related to RR interval, QTc was related to left ventricular ejection fraction (EF) while sex exerted no effects. At the end of the study period heart rate decreased by 8.3% and noncorrected QT increased by 3.0%; QT corrected with the Bazett formula decreased by 0.7% (P = 0.007), QT corrected with the Fridericia formula increased by 0.5% (P = 0.023), whereas the modifications were nonsignificant when the Framingham correction was used. In conclusion, contrary to the current views, physical training and diet, which are effective in reducing heart rate, produced no clinically relevant change in the QT interval.

Could a high-fat diet rich in unsaturated fatty acids impair the cardiovascular system?

BACKGROUND

Dyslipidemia results from consumption of a diet rich in saturated fatty acids and is usually associated with cardiovascular disease. A diet rich in unsaturated fatty acids is usually associated with improved cardiovascular condition.

OBJECTIVE

To investigate whether a high-fat diet rich in unsaturated fatty acids (U-HFD) - in which fatty acid represents approximately 45% of the total calories - impairs the cardiovascular system.

METHODS

Male, 30-day-old Wistar rats were fed a standard (control) diet or a U-HFD containing 83% unsaturated fatty acid for 19 weeks. The in vivo electrocardiogram, the spectral analysis of heart rate variability, and the vascular reactivity responses to phenylephrine, acetylcholine, noradrenaline and prazosin in aortic ring preparations were analyzed to assess the cardiovascular parameters.

RESULTS

After 19 weeks, the U-HFD rats had increased total body fat, baseline glucose levels and feed efficiency compared with control rats. However, the final body weight, systolic blood pressure, area under the curve for glucose, calorie intake and heart weight⁄final body weight ratio were similar between the groups. In addition, both groups demonstrated no alteration in the electrocardiogram or cardiac sympathetic parameters. There was no difference in the responses to acetylcholine or the maximal contractile response of the thoracic aorta to phenylephrine between groups, but the concentration necessary to produce 50% of maximal response showed a decrease in the sensitivity to phenylephrine in U-HFD rats. The cumulative concentration- effect curve for noradrenaline in the presence of prazosin was shifted similarly in both groups.

CONCLUSIONS

The present work shows that U-HFD did not impair the cardiovascular parameters analyzed.

Increased heterogenity of ventricular repolarization in obese nonhypertensive children

OBJECTIVE

Obese children, without arterial hypertension, may be a unique clinical opportunity to evaluate the effect of obesity, per se, on ventricular repolarization, excluding the influence of possible comorbidities. The QTc dispersion (QTc-d), JTc dispersion (JTc-d), and transmural dispersion of repolarization (TDR) have been suggested to be electrocardiographic indexes reflecting the physiological variability of regional ventricular repolarization. The aim of our study is to define the effects of obesity on the ventricular repolarization in obese children who have no other clinically appreciable cause of heart disease.

METHODS

The study involved 70 subjects (48 male, 22 female), with a mean age (± standard deviation) of 13 ± 2 years. A total of 35 individuals were obese (Group A: 24 male, 11 female, mean body mass index [BMI] of 38.2 ± 5.8 kg/m(2) ), and 35 participants were healthy lean children (Group C: 24 male, 11 female, mean BMI of 22.3 ± 0.3 kg/m(2) ). Heart rate; QRS duration; maximum and minimum QT interval; and QTc-d, JTc-d, and TDR measurement were performed.

RESULTS

Compared with the healthy control group, obese children presented increased values of the QTc-d, JTc-d, and TDR (31.1 ± 10.6 vs 46.2 ± 15.3 ms, P < 0.003; 29.8 ± 8.5 vs 40.1 ± 10.3 ms, P < 0.04; 83.2 ± 13.5 vs 100.7 ± 16.3 ms, P < 0.05). A statistically significant correlation was found between the values of QTc-d, insulin serum concentration (r = 0.46, P = 0.04), and homeostasis model assessment of insulin resistance (r = 0.34, P = 0.03).

CONCLUSIONS

Our data suggest that obese nonhypertensive children have an increased ventricular repolarization heterogeneity in relation to controls.

Effect of Weight Loss following Bariatric Surgery on Myocardial Dispersion of Repolarization in Morbidly Obese Patients

BACKGROUND

Weight-stable obese subjects have an increased risk of arrhythmias and sudden death, even in the absence of cardiac dysfunction, and the risk of sudden cardiac death (SCD) with increasing weight is seen in both genders. The mechanism of unexplained deaths in obese patients is still unclear and may be related to ventricular repolarization abnormalities. The aim of this study is to determine the effect of severe obesity on spatial and transmural ventricular repolarization and to clarify the influence of bariatric surgery with a consequent substantial weight loss on arrhythmogenic substrate in the morbidly obese population.

METHODS

For the study, we enrolled 100 severely obese patients; 50 age-matched non-obese healthy subjects were also recruited as controls. All subjects underwent conventional 12-lead electrocardiography for analysis of spatial and transmural ventricular repolarization assessed by corrected QT dispersion (QTc-d), corrected JT dispersion (JTc-d) and transmural dispersion of repolarization, (TDR). All subjects underwent bariatric surgery and were resubmitted to electrocardiographic, biochemical and anthropometric examination 12 months postoperatively.

RESULTS

Severely obese patients had greater values in QTc-d, JTc-d and TDR than the normal-weight controls. Bariatric surgery reduced significantly the QTc-d value, JTc-d value and TDR value. There was a significant correlation between decrease of heterogeneity of repolarization indexes (QTd, JTd and TDR) and bariatric surgery-induced weight loss.

CONCLUSIONS

In severely obese patients, surgically-induced weight loss is associated with significant decrease in the heterogeneity of ventricular repolarization. The reduction of spatial (QTc-d, JTc-d) and transmural dispersion of repolarization (TDR) may be of clinical significance, by reducing the risk of potentially fatal arrhythmias in morbidly obese subjects.

Long-term fish consumption is associated with protection against arrhythmia in healthy persons in a Mediterranean region--the ATTICA study

BACKGROUND

Dietary habits have long been associated with many manifestations of cardiovascular disease.

OBJECTIVE

We sought to investigate whether a diet enriched with fish and n-3 fatty acid consumption are associated with changes in the potential duration of the electrical action, as represented by the QT duration on a resting electrocardiogram, in a population-based sample of Greek adults.

DESIGN

During 2001 and 2002, we randomly enrolled 1514 men (18-87 y old) and 1528 women (18-89 y old) stratified by age and sex distribution (in the 2001 Greek census) from the Attica area, Greece. We studied several demographic, anthropometric, lifestyle, dietary, and bioclinical factors of the participants. Dietary habits (including fish consumption) were evaluated by using a validated food-frequency questionnaire. All subjects underwent electrocardiography with a 12-lead surface, in which, along with several other indexes, QT duration was measured, and the heart rate-corrected QT (QTc) was calculated (corrected by using Bazett's rate). The tested hypothesis was evaluated through multiple linear regression analysis, after control for physical activity status, sex, age, medication intake, and several other potential confounders.

RESULTS

Compared with fish nonconsumers, those who consumed >300 g fish/wk had a mean 13.6% lower QTc (P<0.01). These findings were confirmed after adjustment for age, sex, physical activity status, BMI, smoking habits, intake of nuts, and other confounders. Moreover, compared with fish nonconsumers, those who consumed >or=300 g fish/wk had a 29.2% lower likelihood of having QTc intervals >0.45 s (P=0.03).

CONCLUSIONS

Long-term consumption of fish is associated with lower QTc interval in free-eating people without any evidence of cardiovascular disease. Thus, fish intake seems to provide antiarrhythmic protection at a population level.

Obesity and cardiovascular disease: pathophysiology, evaluation, and effect of weight loss: an update of the 1997 American Heart Association Scientific Statement on Obesity and Heart Disease from the Obesity Committee of the Council on Nutrition, Physical Activity, and Metabolism

Obesity is becoming a global epidemic in both children and adults. It is associated with numerous comorbidities such as cardiovascular diseases (CVD), type 2 diabetes, hypertension, certain cancers, and sleep apnea/sleep-disordered breathing. In fact, obesity is an independent risk factor for CVD, and CVD risks have also been documented in obese children. Obesity is associated with an increased risk of morbidity and mortality as well as reduced life expectancy. Health service use and medical costs associated with obesity and related diseases have risen dramatically and are expected to continue to rise. Besides an altered metabolic profile, a variety of adaptations/alterations in cardiac structure and function occur in the individual as adipose tissue accumulates in excess amounts, even in the absence of comorbidities. Hence, obesity may affect the heart through its influence on known risk factors such as dyslipidemia, hypertension, glucose intolerance, inflammatory markers, obstructive sleep apnea/hypoventilation, and the prothrombotic state, in addition to as-yet-unrecognized mechanisms. On the whole, overweight and obesity predispose to or are associated with numerous cardiac complications such as coronary heart disease, heart failure, and sudden death because of their impact on the cardiovascular system. The pathophysiology of these entities that are linked to obesity will be discussed. However, the cardiovascular clinical evaluation of obese patients may be limited because of the morphology of the individual. In this statement, we review the available evidence of the impact of obesity on CVD with emphasis on the evaluation of cardiac structure and function in obese patients and the effect of weight loss on the cardiovascular system.

Free Fatty Acids, Insulin Resistance, and Corrected QT Intervals in Morbid Obesity: Effect of Weight Loss During 6 Months With Differing Dietary Interventions

OBJECTIVE

To assess whether shortening of the corrected QT (QTc) interval is most closely associated with changes in weight, insulin resistance, or free fatty acids (FFAs) (or some combination of these factors).

METHODS

We randomized 75 severely obese subjects without diabetes to either a low-carbohydrate or a conventional low-fat weight-loss diet for 6 months. We measured QTc, insulin sensitivity, body mass index, and FFAs at baseline and at 6 months. Analysis was performed to determine whether improvement in weight, in insulin resistance, or in FFAs has the greatest effect on reducing the QTc interval.

RESULTS

"Completers" of both the low-carbohydrate diet (N = 25) and the low-fat diet (N = 22) had a decrease in weight, but the weight loss was greater in the low-carbohydrate group. A statistically significant decrease in QTc from baseline was observed only in the low-carbohydrate group. QTc in the low-carbohydrate group correlated with improvement in insulin resistance, but this finding was not significant after correction for the greater weight loss. FFAs or weight loss was not correlated with QTc in either dietary group.

CONCLUSION

Low-carbohydrate dieting is associated with a greater decrease in the QTc interval in comparison with low-fat dieting. Improvements in insulin resistance seem to have a relatively weak mechanistic role, and a decrease in FFAs has no apparent role in the reduction of the QTc interval.

Sympathovagal balance, nighttime blood pressure, and QT intervals in normotensive obese women

OBJECTIVE

We describe associations among the heart-rate-corrected QT (QTc) interval, QTc dispersion (QTc-d), circadian BP variation, and autonomic function in obese normotensive women and the effect of sustained weight loss.

RESEARCH METHODS AND PROCEDURES

In 71 obese (BMI = 37.14 +/- 2.6 kg/m(2)) women, 25 to 44 years of age, circadian BP variations (24-hour ambulatory BP monitoring), autonomic function (power spectral analysis of RR interval oscillations), and cardiac repolarization times (QTc-d and QTc interval) were recorded at baseline and after 1 year of a multidisciplinary program of weight reduction.

RESULTS

Compared with nonobese age-matched women (n = 28, BMI = 23 +/- 2.0 kg/m(2)), obese women had higher values of QTc-d (p < 0.05) and QTc (p < 0.05), an altered sympathovagal balance (ratio of low-frequency/high-frequency power, p < 0.01), and a blunted nocturnal drop in BP (p < 0.01). In obese women, QTc-d and the QTc interval correlated with diastolic nighttime BP (p < 0.01) and sympathovagal balance (p < 0.01). Waist-to-hip ratio, free fatty acids, and plasma insulin levels correlated with QT intervals and reduced nocturnal drops in both systolic and diastolic BP and sympathovagal balance (p < 0.01). After 1 year, obese women lost at least 10% of their original weight, which was associated with decrements of QTc-d (p < 0.02), the QTc interval (p < 0.05), nighttime BP (p < 0.01), and sympathovagal balance (p < 0.02).

DISCUSSION

Sustained weight loss is a safe method to ameliorate diastolic nighttime BP drop and sympathetic overactivity, which may reduce the cardiovascular risk in obese women.

Autonomic dysfunction associates with prolongation of QT intervals and blunted night BP in obese women with visceral obesity

Prolonged QT intervals and a reduced fall of nocturnal blood pressure (BP) both predict an increased risk of cardiovascular events in obese subjects. We evaluated circadian BP variations (24-h ambulatory BP monitoring), autonomic function (power spectral analysis of RR interval oscillations) and cardiac repolarization times (QTc-dispersion and QTc interval) in 70 obese women, aged 25-44 yr, grouped by WHR into group A (WHR > 0.85, no.=38) and group B (WHR < or = 0.85, no.=32). Compared with non-obese age-matched women (no.=25, BMI=23+/-1.8) and obese women of group B, obese women of group A had higher values of QTc-d (p<0.05) and QTc (p<0.05), an altered sympathovagal balance (ratio of low-frequency/high-frequency power, p<0.01), and a blunted nocturnal drop in BP (p<0.01). In group A, QTc-d and the QTc interval correlated with diastolic night BP (p<0.01) and sympathovagal balance (p<0.01). WHR and plasma insulin levels correlated with QT intervals, reduced nocturnal fall in diastolic BP and sympathovagal balance (p<0.01). Prolongation of cardiac repolarization times and the reduction of nocturnal fall in BP coexist in obese women with visceral obesity, and might contribute to their raised cardiovascular risk. Autonomic dysfunction may be the common mechanism for this association.