Atrial fibrillation and obesity--results of a meta-analysis

Periatrial epicardial fat is associated with markers of endothelial dysfunction in patients with atrial fibrillation

Background

Epicardial adipose tissue (EAT) is associated to atrial fibrillation (AF) burden and outcome after AF ablation. We intended to determine whether global or local EAT is associated with systemic and/or left atrial (LA) inflammation and markers of endothelial dysfunction in AF patients.

Methods and Results

Total, atrial, and ventricular EAT volume (EATtotal, EATatrial, EATventricular) were measured by multislice cardiac CT in 49 patients with paroxysmal (PAF, n=25) or persistent AF (PeF, n=24). Periatrial epicardial fat thickness at the esophagus (LA-ESO) and thoracic aorta (LA-ThA) were also measured. Vascular endothelial growth factor (VEGF), interleukin-8 (IL-8), soluble intercellular adhesion molecule 1 (sICAM-1), transforming growth factor-β1 (TGF-β1), and von Willebrand Factor (vWF) levels were measured in peripheral and LA blood samples obtained during catheterization during AF ablation. Patients with PeF had higher EATatrial (P<0.05) and LA-ESO (P=0.04) than patients with PAF. VEGF, IL-8, and TGF-β1 were not associated with EAT. In contrast, after adjusting for LA volume and body mass index, higher LA-ThA was significantly associated with higher sICAM-1 and vWF levels, both in peripheral blood (P<0.05) and in LA (P<0.05). Similar results were found with LA-ESO. Body mass index, EATtotal and EATventricular were not associated with sICAM-1 and vWF.

Conclusions

Periatrial epicardial fat showed a significant positive association with increased levels of sICAM-1 and vWF, which are biomarkers of endothelial dysfunction. No such associations were found when considering body mass index or EATtotal. These results suggest that local EAT rather than regional or total adiposity may modulate endothelial dysfunction in patients with AF.

Chronic baroreflex activation restores spontaneous baroreflex control and variability of heart rate in obesity-induced hypertension

The sensitivity of baroreflex control of heart rate is depressed in subjects with obesity hypertension, which increases the risk for cardiac arrhythmias. The mechanisms are not fully known, and there are no therapies to improve this dysfunction. To determine the cardiovascular dynamic effects of progressive increases in body weight leading to obesity and hypertension in dogs fed a high-fat diet, 24-h continuous recordings of spontaneous fluctuations in blood pressure and heart rate were analyzed in the time and frequency domains. Furthermore, we investigated whether autonomic mechanisms stimulated by chronic baroreflex activation and renal denervation-current therapies in patients with resistant hypertension, who are commonly obese-restore cardiovascular dynamic control. Increases in body weight to ∼150% of control led to a gradual increase in mean arterial pressure to 17 ± 3 mmHg above control (100 ± 2 mmHg) after 4 wk on the high-fat diet. In contrast to the gradual increase in arterial pressure, tachycardia, attenuated chronotropic baroreflex responses, and reduced heart rate variability were manifest within 1-4 days on high-fat intake, reaching 130 ± 4 beats per minute (bpm) (control = 86 ± 3 bpm) and ∼45% and <20%, respectively, of control levels. Subsequently, both baroreflex activation and renal denervation abolished the hypertension. However, only baroreflex activation effectively attenuated the tachycardia and restored cardiac baroreflex sensitivity and heart rate variability. These findings suggest that baroreflex activation therapy may reduce the risk factors for cardiac arrhythmias as well as lower arterial pressure.

Diabetes, Obesity and Atrial Fibrillation: Epidemiology, Mechanisms and Interventions

Body mass index (BMI) is a powerful predictor of death, type 2 diabetes (T2DM) and cardiovascular (CV) morbidity and mortality. Over the last few decades, we have witnessed a global rise in adult obesity of epidemic proportions. Similarly, there has been a parallel increase in the incidence of atrial fibrillation (AF), itself a significant cause of cardiovascular morbidity and mortality. This may be partly attributable to advances in the treatment of coronary heart disease (CHD) and heart failure (HF) improving life expectancy, however, epidemiological studies have demonstrated an independent association between obesity, diabetes and AF, suggesting possible common pathophysiological mechanisms and risk factors. Indeed, cardiac remodeling, haemodynamic alterations, autonomic dysfunction, and diastolic dysfunction have been reported in obese and diabetic cohorts. Moreover, diabetic cardiomyopathy is characterized by an adverse structural and functional cardiac phenotype, which may predispose to the development of AF. In this review, we discuss the pathophysiological and mechanistic relationships between obesity, diabetes and AF, and some of the challenges posed in the management of this high-risk group of individuals.

Cardiovascular magnetic resonance of total and atrial pericardial adipose tissue: a validation study and development of a 3 dimensional pericardial adipose tissue model

BACKGROUND

Recently pericardial adipose tissue (PAT) has been shown to be an independent predictor of atrial fibrillation (AF). Atrial PAT may influence underlying atrial musculature creating a substrate for AF. This study sought to validate the assessment of total and atrial PAT by standard cardiovascular magnetic resonance (CMR) measures and describe and validate a three dimensional atrial PAT model.

METHODS

10 merino cross sheep underwent CMR using a 1.5 Tesla system (Siemens, Sonata, Erlangen, Germany). Atrial and ventricular short axis (SA) images were acquired, using ECG -gated steady state free precession sequences. In order to quantify total volume of adipose tissue, a three dimensional model was constructed from consecutive end-diastolic images using semi-automated software. Regions of adipose tissue were marked in each slice followed by linear interpolation of pixel intensities in spaces between consecutive image slices. Total volume of adipose tissue was calculated as a total volume of the three dimensional model and the mass estimated from volume measurements. The sheep were euthanized and pericardial adipose tissue was removed and weighed for comparison to the corresponding CMR measurements.

RESULTS

All CMR adipose tissue estimates significantly correlated with autopsy measurements (ICC > 0.80; p < 0.03). Intra- observer reliability in CMR measures was high, with 95% levels of agreement within 5.5% (ICC = 0.995) for total fat mass and its individual atrial (95% CI ± 8.3%, ICC = 0.993) and ventricular components (95% CI ± 6.6%, ICC = 0.989). Inter- observer 95% limits of agreement were within ± 10.7% (ICC = 0.979), 7.4% (ICC = 0.991) and 7.2% (ICC = 0.991) for atrial, ventricular and total pericardial adipose tissue, respectively.

CONCLUSION

This study validates the use of a semi-automated three dimensional atrial PAT model utilizing standard (clinical) CMR sequences for accurate and reproducible assessment of atrial PAT. The measurement of local cardiac fat stores via this methodology could provide a sensitive tool to examine the regional effect of fat deposition on atrial substrate which potentially may influence AF ablation strategies in obese patients.

Impact of visceral obesity on cardiac parasympathetic activity in type 2 diabetics after coronary artery bypass graft surgery

OBJECTIVE

The association between adiposity and heart rate variability (HRV) in patients with type 2 diabetes (T2D) after coronary artery bypass graft surgery (CABG) is not well documented. We evaluated the associations between indices of adiposity and HRV in patients with T2D with CABG and quantified the relationships of the volume of visceral (VVAT) and subcutaneous adipose tissue (VSAT) to HRV.

DESIGN AND METHODS

One hundred and thirty-five men with T2D who underwent CABG participated in this study. HRV, BMI, waist circumference (WC), VVAT, and VSAT were measured. Correlations between indices of HRV and adiposity were evaluated and predictors of HRV modulation were identified. Patients were then divided into quartiles of VVAT and VSAT to further evaluate the influence of adiposity on HRV.

RESULTS

Subjects were 65 ± 7 years old (mean ± SD) with a BMI of 30 ± 4 kg/m(2) and a WC of 105 ± 10 cm. BMI (r = -0.19) and WC (r = -0.25) were inversely correlated with low frequencies. VVAT correlated negatively with SD normal-to normal (SDNN) (r = -0.22, P < 0.01), indices of cardiac parasympathetic activity [rMSSD (r = -0.27), NN50 (r = -0.22), pNN50 (r = -0.26; all P < 0.05], and with low (r = -0.37) and high frequencies (r = -0.20; all P < 0.01). Patients with the lowest VVAT had the highest cardiac parasympathetic activity (P < 0.05). VVAT remained the best predictor of cardiac parasympathetic activity after adjustments for confounding parameters (P < 0.01).

CONCLUSION

An increase in visceral adiposity, not BMI, seems to be associated with lower HRV in patients with T2D who had a CABG procedure.

The sympathetic nervous system in obesity hypertension

Abundant evidence supports a role of the sympathetic nervous system in the pathogenesis of obesity-related hypertension. However, the nature and temporal progression of mechanisms underlying this sympathetically mediated hypertension are incompletely understood. Recent technological advances allowing direct recordings of renal sympathetic nerve activity (RSNA) in conscious animals, together with direct suppression of RSNA by renal denervation and reflex-mediated global sympathetic inhibition in experimental animals and human subjects have been especially valuable in elucidating these mechanisms. These studies strongly support the concept that increased RSNA is the critical mechanism by which increased central sympathetic outflow initiates and maintains reductions in renal excretory function, causing obesity hypertension. Potential determinants of renal sympathoexcitation and the differential mechanisms mediating the effects of renal-specific versus reflex-mediated, global sympathetic inhibition on renal hemodynamics and cardiac autonomic function are discussed. These differential mechanisms may impact the efficacy of current device-based approaches for hypertension therapy.

Body mass index and adverse events in patients with incident atrial fibrillation

BACKGROUND

Obesity is associated with the development of atrial fibrillation and may impact atrial fibrillation-related outcomes. To date, no anthropometric measure is included in any risk stratification scheme for stroke and death in atrial fibrillation patients.

METHODS

The prospective Danish Diet, Cancer and Health study is a cohort including 57,053 participants (27,178 men and 29,875 women) aged between 50 and 64 years. The study population for this study included the 3135 patients (2025 men and 1110 women) who developed incident atrial fibrillation during follow-up.

RESULTS

Of the subjects with atrial fibrillation, 1414 (45%) had a body mass index (BMI) in the overweight category (BMI 25 to <30 kg/m(2)) and 767 (24%) were categorized as obese (BMI ≥30 kg/m(2)). During a median follow-up of 4.9 years, 609 deaths and 216 thromboembolic events (98% ischemic strokes) occurred. Using normal-weight patients as reference, the risk of a composite end point of "ischemic stroke, thromboembolism, or death" was significantly higher in overweight (crude hazard ratio [HR] 1.31; 95% confidence interval [CI], 1.09-1.56) and obese patients (crude HR 1.55; 95% CI 1.27-1.90). After adjustment for CHADS2 and CHA2DS2-VASc scores, the HRs for the composite end point were 1.21 (95% CI 1.02-1.45) and 1.31 (95% CI 1.10-1.56), respectively, for overweight and 1.25 (95% CI 1.03-1.53) and 1.36 (95% CI 1.11-1.65), respectively, for obese. Continuous analyses of BMI stratified by sex identified obese men and normal-weight women as the sex-specific "high-risk" categories.

CONCLUSION

Overweight and obesity are risk factors for "ischemic stroke, thromboembolism or death" in patients with atrial fibrillation, even after adjustment for CHADS2 and CHA2DS2-VASc scores. The association between BMI and outcomes among atrial fibrillation patients may be modified by sex.

What do we currently know about metabolic syndrome and atrial fibrillation?

Metabolic syndrome represents a cluster of atherogenic risk factors including hypertension, insulin resistance, obesity, and dyslipidemia. Considering that all of these risk factors could influence the development of atrial fibrillation, an association between atrial fibrillation and the metabolic syndrome has been suggested. Additionally, oxidative stress and inflammation have been involved in the pathogenesis of both metabolic syndrome and atrial fibrillation. The mechanisms that relate metabolic syndrome to the increased risk of atrial fibrillation occurrence are not completely understood. Metabolic syndrome and atrial fibrillation are associated with increased cardiovascular morbidity and mortality. Because atrial fibrillation is the most common arrhythmia, and along with the prevalence of metabolic syndrome constantly increasing, it would be very important to determine the relationship between these 2 entities, especially due to the fact that the risk factors of metabolic syndrome are mainly correctable. This review focused on the available evidence supporting the association between metabolic syndrome components and metabolic syndrome as a clinical entity with atrial fibrillation.

Obesity, diabetes and atrial fibrillation; epidemiology, mechanisms and interventions

The last few decades have witnessed a global rise in adult obesity of epidemic proportions. The potential impact of this is emphasized when one considers that body mass index (BMI) is a powerful predictor of death, type 2 diabetes (T2DM) and cardiovascular (CV) morbidity and mortality [1, 2]. Similarly we have witnessed a parallel rise in the incidence of atrial fibrillation (AF), the commonest sustained cardiac arrhythmia, which is also a significant cause of cardiovascular morbidity and mortality. Part of this increase is attributable to advances in the treatment of coronary heart disease (CHD) and heart failure (HF) improving life expectancy and consequently the prevalence of AF. However, epidemiological studies have demonstrated an independent association between obesity and AF, possibly reflecting common pathophysiology and risk factors for both conditions. Indeed, weight gain and obesity are associated with structural and functional changes of the cardiovascular system including left atrial and ventricular remodeling, haemodynamic alterations, autonomic dysfunction, and diastolic dysfunction. Moreover, diabetic cardiomyopathy is characterized by an adverse structural and functional cardiac phenotype which may predispose to the development of AF [3]. In this review, we discuss the pathophysiological and mechanistic relationships between obesity, diabetes and AF, and the challenges posed in the management of this high-risk group of individuals.

Influence of body mass index on recurrence and quality of life in atrial fibrillation patients after catheter ablation: a meta-analysis and systematic review

BACKGROUND

Accumulating evidence has demonstrated that overweight and obesity, expressed as high body mass index (BMI), are associated with the development of atrial fibrillation (AF) and quality of life (QoL) in AF patients. However, the role of high BMI as a risk factor for prognosis and QoL in AF patients undergoing ablation remains controversial.

HYPOTHESIS

We hypothesized that elevated BMI was correlated with AF recurrence and QoL after an ablative procedure.

METHODS

We performed a comprehensive search of PubMed, EMBASE, and the Cochrane Library. Studies were included if they investigated the association of BMI with AF recurrence and QoL after ablation.

RESULTS

Of the 151 articles identified, 12 studies that enrolled 3286 individuals met the inclusion criteria. Overall, compared with normal-BMI patients, AF recurrence occured more frequently in high-BMI patients after ablation (odds ratio: 1.32, 95% confidence interval: 1.17-1.5, P < 0.001). However, the pooled esimate of odds ratio adjusted for multiple confounders did not reach significance. The summary weighted mean difference of BMI between patients with and without recurrence was 0.43 (95% confidence interval: 0.05-0.81, P = 0.027). In addition, QoL scores were significantly lower in high-BMI than in normal-BMI patients before the ablative procedure, whereas the gap of QoL between normal-BMI and high-BMI groups was decreased at follow-up.

CONCLUSIONS

Results of this meta-analysis suggest 2 points, namely that the tight association between overweight/obesity and AF recurrence after ablation may be partly due to other concomitant conditions, and that impaired QoL in high-BMI groups is significantly improved after ablation.

Atrial fibrillation in the 21st century: a current understanding of risk factors and primary prevention strategies

Atrial fibrillation (AF) is the most common arrhythmia worldwide, and it has a significant effect on morbidity and mortality. It is a significant risk factor for stroke and peripheral embolization, and it has an effect on cardiac function. Despite widespread interest and extensive research on this topic, our understanding of the etiology and pathogenesis of this disease process is still incomplete. As a result, there are no set primary preventive strategies in place apart from general cardiology risk factor prevention goals. It seems intuitive that a better understanding of the risk factors for AF would better prepare medical professionals to initially prevent or subsequently treat these patients. In this article, we discuss widely established risk factors for AF and explore newer risk factors currently being investigated that may have implications in the primary prevention of AF. For this review, we conducted a search of PubMed and used the following search terms (or a combination of terms): atrial fibrillation, metabolic syndrome, obesity, dyslipidemia, hypertension, type 2 diabetes mellitus, omega-3 fatty acids, vitamin D, exercise toxicity, alcohol abuse, and treatment. We also used additional articles that were identified from the bibliographies of the retrieved articles to examine the published evidence for the risk factors of AF.

Impact of obesity on cardiovascular health

This review examines the impact of obesity on cardiovascular health. We will review first, relationship between obesity and hypertension. Second, we will describe obesity-related subclinical abnormalities in cardiovascular function and structure. Third, we will summarize evidence linking obesity to overt cardiovascular disease including coronary artery disease, congestive heart failure, stroke, arrhythmias and sudden cardiac death. Fourth, we will discuss the potential mechanisms underlying increased cardiovascular risk in obese subjects. Last, we will discuss contribution of sleep apnea to the link between obesity and cardiovascular disease. Despite recent progress in understanding epidemiologic and pathophysiological links between obesity and cardiovascular disease, several issues remain to be addressed in the future studies. There is a clear need to identify better markers of obesity-related subclinical cardiovascular damage. Furthermore, we should improve identification of obese subjects at highest cardiovascular risk.

The Role of Pericardial and Epicardial Fat in Atrial Fibrillation Pathophysiology and Ablation Outcomes

Emerging evidence suggests that epicardial and pericardial fat are related to the presence, severity and outcome of AF. These associations, independent of generalized obesity, suggest that they may become increasingly useful as markers for risk stratification or monitoring in the clinical setting. Mechanistically, studies have suggested the effects of epicardial and pericardial fat may be mediated by local adipokines, inflammation, fatty infiltration, modulation of AF drivers and left atrial dilatation. Given the dual epidemics of AF and obesity, in the present paper we review the role that the ectopic adipose tissue surrounding the heart has in the pathogenesis of AF. Further inquiries in this active area of investigation may ultimately lead to new insights in how to best combat these interrelated epidemics and reduce the societal burden of AF.

Association of body mass index, diabetes, hypertension, and blood pressure levels with risk of permanent atrial fibrillation

BACKGROUND

After an initial episode of atrial fibrillation (AF), AF may recur and become permanent. AF progression is associated with higher morbidity and mortality. Understanding the risk factors for permanent AF could help identify people who would benefit most from interventions.

OBJECTIVE

To determine whether body mass index (BMI), diabetes, hypertension, and blood pressure levels are associated with permanent AF among people whose initial AF episode terminated.

DESIGN

Population-based inception cohort study.

PARTICIPANTS

Enrollees in Group Health, an integrated health care system, aged 30-84 with newly diagnosed AF in 2001-2004, whose initial AF terminated within 6 months and who had at least 6 months of subsequent follow-up (N = 1,385).

MAIN MEASURES

Clinical characteristics were determined from medical records. Permanent AF was determined from medical records and ECG and administrative databases. Permanent AF was defined as AF present on two separate occasions 6-36 months apart, without any documented sinus rhythm between the two occasions. Cox proportional hazards models were used to estimate adjusted hazard ratios (HRs).

KEY RESULTS

Five-year cumulative incidence of permanent AF was 24 %. Compared with normal BMI (18.5-24.9 kg/m(2)), BMI levels of 25.0-29.9 (overweight), 30.0-34.9 (obese 1), 35.0-39.9 (obese 2), and ≥ 40.0 kg/m(2) (obese 3) were associated with HRs of permanent AF of 1.26 (95 % CI: 0.92, 1.72); 1.35 (0.96, 1.91); 1.50 (0.97, 2.33); and 1.79 (1.13, 2.84), adjusted for age, sex, diabetes, hypertension, blood pressure, coronary heart disease, valvular heart disease, heart failure, and prior stroke. Diabetes, hypertension, and blood pressure were not associated with permanent AF.

CONCLUSIONS

For people whose initial AF episode terminates, benefits of having lower BMI may include a lower risk of permanent AF. Risk of permanent AF was similar for people with and without diabetes or hypertension and across blood pressure levels.

Comparison of Atrial Fibrillation in the Young versus That in the Elderly: A Review

The incidence and prevalence of atrial fibrillation (AF) are projected to increase significantly worldwide, imposing a significant burden on healthcare resources. The disease itself is extremely heterogeneous in its epidemiology, pathophysiology, and treatment options based on individual patient characteristics. Whilst ageing is well recognised to be an independent risk factor for the development of AF, this condition also affects the young in whom the condition is frequently symptomatic and troublesome. Traditional thinking suggests that the causal factors and pathogenesis of the condition in the young with structurally normal atria but electrophysiological "triggers" in the form of pulmonary vein ectopics leading to lone AF are in stark contrast to that in the elderly who have AF primarily due to an abnormal substrate consisting of fibrosed and dilated atria acting in concert with the pulmonary vein triggers. However, there can be exceptions to this rule as there is increasing evidence of structural and electrophysiological abnormalities in the atrial substrate in young patients with "lone AF," as well as elderly patients who present with idiopathic AF. These reports seem to be blurring the distinction in the pathophysiology of so-called idiopathic lone AF in the young versus that in the elderly. Moreover with availability of improved and modern investigational and diagnostic techniques, novel causes of AF are being reported thereby seemingly consigning the diagnosis of "lone AF" to a rather mythical existence. We shall also elucidate in this paper the differences seen in the epidemiology, causes, pathogenesis, and clinical features of AF in the young versus that seen in the elderly, thereby requiring clearly defined management strategies to tackle this arrhythmia and its associated consequences.

Genetic determinants of obesity and related vascular diseases

Obesity is one of the major risk factors of vascular diseases, and its prevalence is increasing worldwide. In the past decade, progress has been made in the understanding of genetic determinants of obesity and obesity-associated diseases. Genome-wide association studies identified a number of genetic variants associated with obesity. In addition to common variants, FTO and MC4R, new loci, such as TMEM18, KCTD15, GNPDA2, SH2B1, MTCH2, and NEGR1 have been detected. In the past years, abdominal obesity has been shown to be a more important vascular risk factor than the body mass index. In the context of vascular risk assessment, identification of genetic polymorphisms associated with accumulation of visceral fat is of special importance. Some polymorphisms associated with abdominal obesity, such as variants of gene encoding microsomal triglyceride transfer protein, have been already discovered. In this chapter, we provide a review of genetic determinants of obesity and discuss their role in obesity-related vascular diseases.

Atrial Fibrillation and Metabolic Syndrome: Understanding the Connection

Metabolic syndrome, a constellation of conditions including obesity, dyslipidemia, hypertension and insulin resistance, has increased to epidemic proportions. Metabolic syndrome has been recognized as a risk factor for cardiovascular morbidity and is likely related to the epidemic of cardiovascular diseases. Perhaps not coincidentally, its growth in incidence has paralleled that of atrial fibrillation. Various components of metabolic syndrome have been known to have a role in the pathogenesis of atrial fibrillation. With the conglomeration of components seen in the metabolic syndrome, the risk for atrial fibrillation increases greatly. Several studies have elucidated the role of metabolic syndrome in the development of atrial fibrillation. Its role on the atrial substrate makes it an important determinant of progression of disease and failure of therapeutic strategies such as catheter ablation. Control of the various components of metabolic syndrome may ultimately lead to better outcomes in atrial fibrillation patients.

Prediction of new onset atrial fibrillation after cardiac revascularization surgery

The aim of this study was to create a simple risk index to predict new-onset atrial fibrillation (AF) after coronary artery bypass grafting in patients with histories of AF. AF after coronary artery bypass grafting (referred to here as AF) is associated with increased morbidity and mortality. Identifying patients at high risk for developing AF may help identify a group of patients who might benefit from strategies to prevent postoperative AF. A cohort of 18,517 patients enrolled from January 1, 1996, to December 31, 2009, was used to derive a risk index for AF prediction. A multivariate logistic regression model determined the independent predictive impact of clinical and demographic characteristics on the occurrence of AF. A subset of these variables was used to construct a risk index to predict AF. This risk index was validated in a sequential cohort of 1,378 consecutive patients who underwent coronary artery bypass grafting from January 1, 2010, to June 30, 2011. AF occurred in 3,486 patients in the calibration cohort (18.83%) and in 269 patients in the validation cohort (19.52%). After considering patients' demographics, co-morbid conditions, and severity of illness, advanced age appeared as the most powerful predictor of AF (odds ratio 1.059/year, 95% confidence interval 1.055 to 1.063). Age, height, weight, and the presence of peripheral vascular disease contributed most to the prediction model. An AF risk index including these variables had adequate discriminatory power, with a concordance index of 0.68. In conclusion, using a large cohort of patients, a simple risk index relying only on preoperative clinical variables was developed, which will help predict AF. This risk index can be used clinically to identify patients at high risk for the development of AF.

Atrial Fibrillation Ablation in Obese Patients

Despite the increased burden of atrial fibrillation (AF), obese patients have similar, if not slightly improved, mortality, described as the "obesity paradox." Catheter ablation for AF in obese patients is a reasonable option, but patients should be screened for sleep apnea and counseled about the possibility of longer procedure times and repeat procedures to achieve similar success rates. Quality of life will likely improve after successful ablation. Although no statistically significant increases in procedural complications have occurred in obese subjects, patients should be counseled about the increased radiation dose and higher incidence of left atrial thrombus preablation.

Does location of epicardial adipose tissue correspond to endocardial high dominant frequency or complex fractionated atrial electrogram sites during atrial fibrillation?

BACKGROUND

Although increased epicardial adipose tissue (EAT) volume is known to be associated with increased prevalence of atrial fibrillation (AF), the exact mechanisms are unclear. Therefore, we investigated whether EAT locations were associated with high dominant frequency (DF) sites or complicated fractionated atrial electrogram sites during AF.

METHODS AND RESULTS

Three-dimensional reconstruction computed tomography images depicting EAT volumes (obtained by 320-detector-row multislice computed tomography) were merged with NavX-based DF and complicated fractionated atrial electrogram maps obtained during AF for 16 patients with paroxysmal AF and for 18 patients with persistent AF. Agreement between locations of the EAT, especially EAT surrounding the left atrium, and of high DF or complicated fractionated atrial electrogram sites was quantified. In addition, serum biomarker levels were determined. EAT surrounding the left atrium volumes was significantly greater in patients with persistent AF than in patients with paroxysmal AF (52.9 cm(3) [95% CI, 44.2-61.5] versus 34.8 cm(3) [95% CI, 26.6-43.0]; P=0.007). Serum high-sensitivity C-reactive protein and interleukin-6 levels were significantly higher in persistent AF patients than in paroxysmal AF patients (median high-sensitivity C-reactive protein, 969 ng/mL [interquartile range, 307-1678] versus 320 ng/mL [interquartile range, 120-660]; P=0.008; median interleukin-6, 2.4 pg/mL [interquartile range, 1.7-3.2] versus 1.3 [interquartile range, 0.8-2.4] pg/mL; P=0.017). EAT locations were in excellent agreement with high DF sites (κ=0.77 [95% CI, 0.71-0.82]) but in poor agreement with complicated fractionated atrial electrogram sites (κ=0.22 [95% CI, 0.13-0.31]).

CONCLUSIONS

Increased EAT volume and elevation of inflammatory biomarkers are noted in persistent AF rather than paroxysmal AF patients. High DF sites are located adjacent to EAT sites. Thus, EAT may be involved in the maintenance of AF.

Electrophysiological and hemodynamic characteristics associated with obesity in patients with atrial fibrillation

OBJECTIVES

The authors sought to characterize the left atrial (LA) and pulmonary vein (PV) electrophysiological and hemodynamic features in obese patients with atrial fibrillation (AF).

BACKGROUND

Obesity is associated with increased risk for AF.

METHODS

A total of 63 consecutive patients with AF who had normal left ventricular (LV) ejection fraction and who underwent catheter ablation were studied. Atrial and PV electrophysiological studies were performed at the time of ablation with hemodynamic assessment by cardiac catheterization, and LA/LV structure and function by echocardiography. Patients were compared on the basis of body mass index (BMI): <25 kg/m(2) (n = 19) and BMI ≥30 kg/m(2) (n = 44).

RESULTS

At a 600-ms pacing cycle length, obese patients had shorter effective refractory period (ERP) in the left atrium (251 ± 25 ms vs. 233 ± 32 ms, p = 0.04), and in the proximal (207 ± 33 ms vs. 248 ± 34 ms, p < 0.001) and distal (193 ± 33 ms vs. 248 ± 44 ms, p < 0.001) PV than normal BMI patients. Obese patients had higher mean LA pressure (15 ± 5 mm Hg vs. 10 ± 5 mm Hg, p < 0.001) and LA volume index (28 ± 12 ml/m(2) vs. 21 ± 14 ml/m(2), p = 0.006), and lower LA strain (5.5 ± 3.1% vs. 8.8 ± 2.8%; p < 0.001) than normal BMI patients.

CONCLUSIONS

Increased LA pressure and volume, and shortened ERP in the left atrium and PV are potential factors facilitating and perpetuating AF in obese patients with AF.

The role of obesity and sleep apnea in atrial fibrillation

PURPOSE OF REVIEW

To discuss the relationship between obesity and obstructive sleep apnea as they relate to the growing atrial fibrillation epidemic, and to discuss possible mechanistic links and implications for treatment of atrial fibrillation.

RECENT FINDINGS

Increasing BMI plays an important role in development of atrial fibrillation in both men and women. Sleep-disordered breathing contributes to cardiac chamber enlargement, which may be responsible for increasing atrial fibrillation in this population. Patients with obstructive sleep apnea and/or obesity have less freedom from atrial fibrillation recurrence after catheter ablation for atrial fibrillation.

SUMMARY

BMI is a strong predictor of future development of atrial fibrillation and should be considered as a risk factor for atrial fibrillation. Patients with obstructive sleep apnea and/or obesity have high atrial fibrillation recurrence rates following atrial fibrillation ablation.

Asymmetric Dimethylarginine Levels are Highly Associated With Atrial Fibrillation in an Elderly Population

BACKGROUND

The importance of endothelial dysfunction in atrial fibrillation (AF) is not clarified. The aim of this study was to evaluate endothelial dysfunction assessed by selected inflammatory and haemostatic endothelial markers and nitric oxide (NO) associated variables as related to the presence of AF in an elderly population. NO is known to express anti-thrombotic as well as vasoactive properties.

METHODS

This is a cross sectional study of 75-year old subjects with AF (n = 62) and control subjects in sinus rhythm (n = 124), matched for gender. Fasting blood samples were collected for analyses of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO-synthase, L-arginine, E-selectin, vascular cell adhesion molecule-1 (VCAM-1) and von Willebrand factor (vWF).

RESULTS

Levels of vWF and ADMA were significantly higher in AF patients vs controls (P = 0.023 and P < 0.001, respectively) and the L-arginine/ADMA ratios were lower (P = 0.015), the latters still significant after adjustment for relevant covariates (P = 0.007 and P = 0.037, respectively). No significant differences in the levels of VCAM-1 and E-selectin were observed between the groups. When dividing the ADMA levels into quartiles there was a significant trend for having AF with increasing levels of ADMA (P < 0.001) with a cut-off at the 25th percentile (< 0.54 µmol/L), giving an adjusted OR for having AF of 12.46 (95% CI 3.11 - 49.86) (P < 0.001) with higher levels. A similar inverse trend was seen for the L-arginine/ADMA ratio.

CONCLUSION

Our population of 75-year-old AF patients had significantly impaired endothelial function assessed by increased levels of vWF, and more pronounced by high levels of ADMA. The results indicate AF in the elderly to be closely associated with the regulatory pathway of NO.

Atrial fibrillation in two adolescents

Idiopathic atrial fibrillation (AF) in adolescents is extremely rare and has usually been associated with structural heart disease. We present two cases of symptomatic AF in adolescents without any identifiable etiology. No definitive guidelines are available for management of such patients.

Epicardial Fat and Atrial Fibrillation: A Review

Atrial fibrillation (AF) is a progressive disorder that increases with age. Obesity is an important risk factor for AF. Pericardial fat is an active adipose tissue in close proximity to the heart and has been shown to be a risk factor for structural as well as coronary artery disease independent of body mass index. Recent studies suggest a role of epicardial fat in atrial remodeling as well as AF burden. This review will summarize the recent evidence linking epicardial fat and AF.

Lone atrial fibrillation: where are we now?

There is a growing pandemic of atrial fibrillation (AF), affecting nearly 2% of the general adult population. Atrial fibrillation is commonly associated with structural heart disease, and AF itself causes a sequence of complex processes of electrical, contractile, and structural remodeling of the atrial myocardium, which facilitate further AF progression. Nonetheless, AF may also affect individuals aged ≤ 65 years who have no evidence of associated cardiopulmonary or other disease, including hypertension; this is otherwise referred to as "lone" AF and is considered to have a generally favorable prognosis. The true prevalence of lone AF is unknown. Growing insights into the diversity of numerous mechanisms involved in the pathogenesis of AF, including acute atrial stretch, structural and electrophysiological alterations, systemic inflammation, oxidative stress, autonomic imbalance, genetic predisposition, and many others, and increasing recognition of novel risk factors for AF, including obesity, metabolic syndrome, subclinical atherosclerosis, sleep apnea, alcohol consumption, and endurance sports, suggest that apparently lone AF might not be so "lone" in many patients, which could have important prognostic and therapeutic implications. In this article, we summarize the current knowledge of epidemiology, etiopathogenesis, and pathophysiology of so-called lone AF and discuss the issues of long-term prognosis and management of patients who have an apparently lone AF.

P-wave dispersion for predicting paroxysmal atrial fibrillation in acute ischemic stroke

BACKGROUND

Detection of paroxysmal atrial fibrillation (PAF) in acute ischemic stroke patients poses diagnostic challenge. The aim of this study was to predict the presence of PAF by means of 12-lead ECG in patients with acute ischemic stroke. Our hypothesis was that P-wave dispersion (P(d)) might be a useful marker in predicting PAF in patients with acute ischemic stroke.

METHODS

12-lead resting ECGs, 24-hour Holter recordings and echocardiograms of 400 patients were analyzed retrospectively. PAF was detected in 40 patients on 24-hour Holter monitoring. Forty out of 360 age and gender matched patients without PAF were randomly chosen and assigned as the control group. Demographics, P-wave characteristics and echocardiographic findings of the patients with and without PAF were compared.

RESULTS

Maximum P-wave duration (p=0.002), P(d) (p<0.001) and left atrium diameter (p=0.04) were significantly higher in patients with PAF when compared to patients without PAF. However, in binary logistic regression analysis P(d) was the only independent predictor of PAF. The cut-off value of P(d) for the detection of PAF was 57.5 milliseconds (msc). Area under the curve was 0.80 (p<0.001). On a single 12-lead ECG, a value higher than 57.5 msc predicted the presence of PAF with a sensitivity of 80% and a specificity of 73%.

CONCLUSION

P(d) on a single 12-lead ECG obtained within 24 hours of an acute ischemic stroke might help to predict PAF and reduce the risk of recurrent strokes.

Medical complications of obesity and optimization of the obese patient for colorectal surgery

Obesity is a medical epidemic with an enormous impact on disease prevalence and health care utilization. In the preoperative period, an awareness of medical issues associated with obesity is an important part of the planning for surgical procedures. The authors highlight the diagnostic and treatment options for medical conditions commonly affecting the obese patient including diabetes, hypertension, coronary artery disease, and deep venous thrombosis.

Lipoprotein(a) and inflammation in patients with atrial fibrillation after electrical cardioversion

Background

Recently few studies tried to confirm the association between AF and lipoprotein(a) (Lp(a)), however the results remained conflicted. In present study we evaluated the possible interaction between Lp(a), inflammatory state and echocardiographic characteristics in patients after successful electrical cardioversion (EC) of persistent AF. We also tried to investigate the role of Lp(a) as a possible prognostic factor for AF recurrence after successful EC.

Results

Data of 79 patients admitted due to planned EC was analyzed. After successful procedure patients were monitored for 2 years. For analytical purposes patients were divided in two groups according to AF recurrence. There was no significant difference between Lp(a) levels in both groups. We also didn't find any positive correlation between Lp(a) and CRP levels, as well as between Lp(a) levels and left atrium diameter. For logistic and survival analysis optimal cut-off value of Lp(a) ≥ 0.32 (upper quartile) was used. In logistic regression model with AF recurrence as dependent variable Lp(a) didn't show any statistically significant association with AF recurrence. Survival analysis showed slightly higher AF recurrence rate in group with higher Lp(a) levels but not to the level of statistical significance (log rank test, p = 0.62).

Conclusions

We weren't able to confirm the association between Lp(a) levels and AF recurrence, inflammation and left atrium diameter in patients after successful EC of persistent AF. Further studies are needed to elucidate the role of Lp(a) in this clinical setting.

Predictors of incident atrial fibrillation and influence of medications: a retrospective case-control study

BACKGROUND

Atrial fibrillation (AF) is a common condition, associated with raised mortality and risk of major morbidity, and is predicted to increase due to an aging population.

AIM

To update earlier research of AF predictors using UK data.

DESIGN AND SETTING

Case-control analysis of adults aged 18 years and older with a diagnosis of AF in practices registered with the General Practice Research Database (GPRD) in the UK.

METHOD

Using the GPRD, a case.control analysis was performed using logistic regression to compare 55,412 incident AF cases to 216,400 controls, for medical history and prior use of drugs. The association between time since start of diagnosis or drug use and AF risk was summarised using Spline regression.

RESULTS

The following were confirmed as risk factors for AF: heart failure (risk ratio [RR] 2.91 [95% CI = 2.59 to 3.27]); ischaemic heart disease (IHD) (RR 2.00 [95% CI = 1.78 to 2.24]); hypertension (RR 2.60 [95% CI = 2.32 to 2.92]); hyperthyroidism (RR 1.56 [95% CI = 1.39 to 1.75]); being a heavy drinker (RR 1.43 [95% CI = 1.27 to 1.60]); cerebrovascular accident (RR 1.48 [95% CI = 1.32 to 1.66]); and obesity (body mass index ≥30 kg/m(2) RR 1.29 [95% CI = 1.15 to 1.45]). Current use of oral glucocorticoids (RR 1.62 [95% CI = 1.44 to 1.82]) and of beta-2 agonists (RR 1.30 [95% CI = 1.16 to 1.46]) were identified as significant risk factors, and statins (RR 0.82 [95% CI = 0.73 to 0.92]) as a significant protective factor. No effect was found for current use of bisphosphonates (RR 0.95 [95% CI = 0.85 to 1.07]), renin.angiotensin.aldosterone system (RAAS) agents (RR 1.04 [95% CI = 0.93 to 1.17]), or xanthine derivatives (RR 1.09 [95% CI = 0.97 to 1.22]). Spline regression analysis found the effect of heart failure, IHD, use of oral glucocorticoids, and use of statins on the likelihood of developing AF was sustained over a number of years.

CONCLUSION

These findings update the risk factors that are associated with AF, and confirm the protective properties of statins and the risks of beta-2 agonists in developing AF, but not the supposed protective qualities of glucocorticoids and RAAS agents.

Body composition and coronary heart disease mortality--an obesity or a lean paradox?

OBJECTIVE

To determine the combined effects of body mass index (BMI) and body fat (BF) on prognosis in coronary heart disease (CHD) to better understand the obesity paradox.

PATIENTS AND METHODS

We studied 581 patients with CHD between January 1, 2000, and July 31, 2005, who were divided into low (<25) and high BMI (≥25), as well as low (≤25% men and ≤35% women) and high BF (>25% in men and >35% in women). Four groups were analyzed by total mortality during the 3-year follow-up by National Death Index: low BF/low BMI (n=119), high BF/low BMI (n=26), low BF/high BMI (n=125), and high BF/high BMI (n=311).

RESULTS

During the 3-year follow-up, mortality was highest in the low BF/low BMI group (11%), which was significantly (P<.001) higher than that in the other 3 groups (3.9%, 3.2%, and 2.6%, respectively); using the high BF/high BMI group as a reference, the low BF/low BMI group had a 4.24-fold increase in mortality (confidence interval [CI], 1.76-10.23; P=.001). In multivariate logistic regression for mortality, when entered individually, both high BMI (odds ratio [OR], 0.79; CI, 0.69-0.90) and high BF (OR, 0.89; CI, 0.82-0.95) as continuous variables were independent predictors of better survival, whereas low BMI (OR, 3.60; CI, 1.37-9.47) and low BF (OR, 3.52; CI, 1.34-9.23) as categorical variables were independent predictors of higher mortality.

CONCLUSION

Although both low BF and low BMI are independent predictors of mortality in patients with CHD, only patients with combined low BF/low BMI appear to be at particularly high risk of mortality during follow-up. Studies are needed to determine optimal body composition in the secondary prevention of CHD.

Association of body mass index with new-onset atrial fibrillation after coronary artery bypass grafting operations

BACKGROUND

Postoperative atrial fibrillation (AF) frequently complicates coronary artery bypass grafting (CABG) operations. As the frequency of obesity has increased in the United States, the number of obese patients undergoing CABG has kept pace. This study sought to define the association between body mass index (BMI) and postoperative AF.

METHODS

We studied 12,367 consecutive patients with no history of AF who underwent isolated CABG operations. BMI was stratified according to Centers for Disease Control and Prevention criteria, and differences in baseline clinical and operative characteristics were adjusted through multivariate logistic regression models.

RESULTS

The unadjusted incidence of new-onset postoperative AF demonstrated a U-shape with regard to BMI. The highest incidence (34%) was found in the "lean" stratum (BMI<18.5 kg/m2), followed by 32% in the "severely obese" (BMI≥40 kg/m2) stratum. Lower incidences were found in the "normal" stratum (30%), in the "obese" stratum (28%), and the lowest incidence (26%) was in the overweight stratum. Observed incidence was 50% greater than the expected incidence in the "severely obese" stratum (32% vs 21%). In multivariate regression analysis adjusted for age and other covariates, BMI remains a strong risk factor for new-onset postoperative AF. Compared with normal BMI, obesity (odds ratio, 1.24; 95% confidence interval, 1.08 to 1.42) and severe obesity (odds ratio, 2.00; 95% confidence interval, 1.54 to 2.57) both emerged as strong risk factors for postoperative AF. No association was found between a lean BMI and postoperative AF (odds ratio, 1.14; 95% confidence interval, 0.66 to 1.98).

CONCLUSIONS

After adjusting for potential confounders, obesity, as reflected by the body mass index, remains an independent predictor of postoperative AF.

The impact of body mass index on the efficacy and safety of catheter ablation of atrial fibrillation

BACKGROUND

Obesity is a well established risk factor for atrial fibrillation (AF) development. Our purpose was to determine the impact of body mass index (BMI) on the safety and efficacy of radiofrequency catheter ablation of AF.

METHODS

Two hundred and twenty-six consecutive patients with symptomatic, drug-refractory paroxysmal (59.3%) and persistent (40.7%) AF underwent wide circumferential electrical pulmonary vein isolation. Patients were classified according to BMI as normal (<25kg/m(2)); overweight (25 to 29.9kg/m(2)); and obese (≥30kg/m(2)).

RESULTS

Patients with high BMI were younger and displayed a higher rate of hypertension, increased left atrial diameter, increased left ventricular end-diastolic and end-systolic diameters, and increased levels of several conventional markers of inflammation and oxidative stress including white blood cell count, fibrinogen, uric acid, alanine aminotransferase, and gamma-glutamyltransferase (p<0.05). After a mean follow-up period of 432.32±306.09days from the index procedure, AF recurrence rate was 34.9% for normal weight, 46.2% for overweight, and 46.2% for obese patients (p: 0.258). Subjects classified above the 50th percentile for BMI displayed a trend toward a higher AF recurrence rate (p: 0.08). In univariate Cox regression survival analysis, BMI was not predictive of AF recurrence. Radiation exposure was significantly higher in overweight and obese patients in relation to normal weight patients (p: 0.003). No significant differences regarding major complications were observed among BMI groups.

CONCLUSIONS

In this study population, BMI was not an independent predictor of AF recurrence following left atrial catheter ablation.

QRS duration is associated with atrial fibrillation in patients with left ventricular dysfunction

BACKGROUND

QRSduration (QRSd) is associated with higher mortality and morbidity in patients with left ventricular (LV) dysfunction. The association between QRSd and atrial fibrillation (AF) has not been studied in this patient population.

OBJECTIVES

To investigate the association between QRSd and AF in patients with LV dysfunction.

METHODS

Data were obtained from the National Registry to Advance Heart Health (ADVANCENT) registry, a prospective multicenter registry of patients with left ventricular ejection fraction (LVEF) < or = 40%. A total of 25 268 patients from 106 centers in the United States, were enrolled between June 2003 and November 2004. Demographic and clinical characteristics of patients were collected from interviews and medical records.

RESULTS

: Mean age was 66.3+/-13 years, 71.5% were males, and 81.9% were white. A total of 14 452 (57.8%) patients had a QRSd < 120 ms, 5304 (21.2%) had a QRSd between 120 and 150 ms, and 5269 (21%) had a QRSd > 150 ms. Atrial fibrillation occurred in 20.9%, 27.5%, and 35.5% of patients in the QRS groups, respectively (P < 0.0001). After adjusting for potential AF risk factors (age, gender, race, body mass index, hypertension, diabetes, renal failure, cancer, lung disease, New York Heart Association [NYHA] class, ejection fraction, etiology of cardiomyopathy) and the use of angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta-blockers, and lipid lowering drugs, QRS duration remained independently associated with AF (odds ratio: 1.20, 95% confidence interval: 1.14-1.25).

CONCLUSION

In this large cohort of patients, QRSd was strongly associated with AF and therefore may predict the occurrence of this arrhythmia in patients with LV dysfunction. This association persisted after adjusting for disease severity, comorbid conditions, and the use of medications known to be protective against AF.

Intensive care in the obese

Nearly 20% of all patients admitted to an intensive-care unit are obese. Their excess weight puts them at risk for several problems and complications during their intensive-care unit stay. Especially, pulmonary problems need particular attention, and comprehensive knowledge of the specific pathophysiologic changes of the respiratory system is important. Lung protective ventilation strategies, supplemented by lung-recruiting manoeuvres, may be feasible in critically ill obese patients with lung injury. Careful positioning of the obese is essential to optimise ventilation and facilitate weaning from mechanical ventilation. Optimal hypocaloric nutrition with a high proportion of proteins is advised to control hyperglycaemia. Because mortality in obese patients is similar to or lower than in non-obese ones, it is conceivable that obesity has a protective effect in the critically ill.

Assessment of atrial electromechanical delay by tissue Doppler echocardiography in obese subjects

Our aim was to evaluate whether atrial electromechanical delay measured by tissue Doppler imaging (TDI), which is an early predictor of atrial fibrillation (AF) development, is prolonged in obese subjects. A total of 40 obese and 40 normal-weight subjects with normal coronary angiograms were included in this study. P-wave dispersion (PWD) was calculated on the 12-lead electrocardiogram (ECG). Systolic and diastolic left ventricular (LV) functions, inter- and intra-atrial electromechanical delay were measured by TDI and conventional echocardiography. Inter- and intra-atrial electromechanical delay were significantly longer in the obese subjects compared with the controls (44.08 ± 10.06 vs. 19.35 ± 5.94 ms and 23.63 ± 6.41 vs. 5.13 ± 2.67 ms, P < 0.0001 for both, respectively). PWD was higher in obese subjects (53.40 ± 5.49 vs. 35.95 ± 5.93 ms, P < 0.0001). Left atrial (LA) diameter, LA volume index and LV diastolic parameters were significantly different between the groups. Interatrial electromechanical delay was correlated with PWD (r = 0.409, P = 0.009), high-sensitivity C-reactive protein (hsCRP) levels (r = 0.588, P < 0.0001). Interatrial electromechanical delay was positively correlated with LA diameter, LA volume index, and LV diastolic function parameters consisting of mitral early wave (E) deceleration time (DT) and isovolumetric relaxation time (IVRT; r = 0.323, P = 0.042; r = 0.387, P = 0.014; r = 0.339, P = 0.033; r = 0.325, P = 0.041; respectively) and, negatively correlated with mitral early (E) to late (A) wave ratio (E/A) (r = -0.380, P = 0.016) and myocardial early-to-late diastolic wave ratio (E(m)/A(m)) (r = -0.326, P = 0.040). This study showed that atrial electromechanical delay is prolonged in obese subjects. Prolonged atrial electromechanical delay is due to provoked low-grade inflammation as well as LA enlargement and early LV diastolic dysfunction in obese subjects.

Lone atrial fibrillation: what is known and what is to come

Atrial fibrillation (AF) is the most prevalent sustained cardiac arrhythmia in adults, affecting >1% of general population. Atrial fibrillation is commonly associated with structural heart disease and is a major cause of significant cardiovascular morbidity and mortality. AF sometimes develops in a subset of young patients (e.g. aged ≤60 years), with no evidence of associated cardiopulmonary or other comorbid disease (including hypertension), and has been referred to as 'lone AF'. The latter generally has a favourable prognosis; the prognostic and therapeutic implications of an accurate identification of patients with truly lone AF (that is, truly at low risk of complications), if any, would be of the utmost importance. The true prevalence of lone AF is unknown, varying between 1.6% and 30%, depending on the particular study population. Nonetheless, novel risk factors for AF, including obesity, metabolic syndrome, sleep apnea, alcohol consumption, endurance sports, anger, hostility, subclinical atherosclerosis and others, have been increasingly recognised. Also, various underlying pathophysiological mechanisms predisposing to AF, including increased atrial stretch, structural and electrophysiological alterations, autonomic imbalance, systemic inflammation, oxidative stress and genetic predisposition, have been proposed. The growing evidence of these diverse (and numerous) pathogenic mechanisms and factors related to AF inevitably raises the question of whether 'lone AF' does exist at all. In this review article, we summarise the current knowledge of the epidemiology, pathophysiology, clinical course and treatment of patients with so-called 'lone AF' and outline emerging insights into its pathogenesis and the potential therapeutic implications of a diagnosis of lone AF.

Relation of obesity to recurrence rate and burden of atrial fibrillation

Obesity is associated with new-onset atrial fibrillation (AF). However, the effect of obesity on AF recurrence or burden has not been studied. The aim of this study was to investigate the relation between AF recurrence, AF burden, and body mass index (BMI). A limited-access data set from the Atrial Fibrillation Follow-Up Investigation of Rhythm Management (AFFIRM) trial provided by the National Heart, Lung, and Blood Institute was used. Statistical analysis was done with a generalized linear mixed model. In 2,518 patients who had BMIs recorded, higher BMI was associated with a higher number of cardioversions (odds ratio [OR] 1.017, 95% confidence interval [CI] 1.005 to 1.029 for a BMI increase of 1 kg/m(2); OR 1.088, 95% CI 1.024 to 1.155 for a BMI increase of 5 kg/m(2); OR 1.183, 95% CI 1.049 to 1.334 for a BMI increase of 10 kg/m(2); p = 0.006 for each). Increased BMI was also associated with a higher likelihood of being in AF on follow-up (OR 1.020, 95% CI 1.002 to 1.038 per 1 kg/m(2) increased BMI, p = 0.0283; OR 1.104, 95% CI 1.011 to 1.205 per 5 kg/m(2) increased BMI, p = 0.0283; OR 1.218, 95% CI 1.021 to 1.452 per 10 kg/m(2) increased BMI, p = 0.0283). In a multivariate analysis, left atrial size but not BMI was an independent predictor of AF recurrence and AF burden. Because left atrial size was correlated with BMI, the effect of BMI on AF can be likely explained by greater left atrial size in subjects with higher BMIs. In conclusion, obesity is associated with a higher incidence of recurrence of AF and greater AF burden.