Prevalence of abnormal glucose metabolism in atrial fibrillation: a case control study in 75-year old subjects

Excessive dietary sodium intake augments long-term risk of atrial fibrillation in older adults with hyperglycemia: A community-based prospective cohort study

AIM

Studies investigating the association between sodium intake and new-onset atrial fibrillation (AF) have come to controversial results. This study aimed to assess the effect of excessive sodium intake on new-onset AF in individuals with hyperglycemia.

METHODS

Between April 2007 and November 2011, 2841 community-dwelling individuals aged 60 years and older were recruited from the Shandong area, China. Dietary sodium intake was estimated using 24-hour urine collection within seven consecutive days. Fasting plasma glucose (FPG) and glycated hemoglobin (HbA1c) were assessed. New-onset AF was diagnosed using ICD-10 with codes I48 (I48.0 - I48.9) during follow-up.

RESULTS

The findings were that excessive sodium intake significantly and independently increased the risk of new-onset AF in older adults with hyperglycemia: hazard ratio (HR) 1.525 [95% confidence interval 1.147;2.029] adjusted P = 0.004. The risk of new-onset AF increased by 29.3% (HR 1.293 [1.108;1.509] adjusted P = 0.001) with a one-standard deviation increase in sodium intake. Excessive sodium intake synergistically interacted with hyperglycemia on the increased risk of new-onset AF (HR 1.599 [1.342;1.905] adjusted P < 0.001 for FPG and HR 1.516 [1.271;1.808] adjusted P < 0.001 for HbA1c).

CONCLUSION

Our findings indicate that excessive sodium intake independently enhances the risk of new-onset AF among patients with hyperglycemia. A sodium-restricted diet may perhaps result in a multiplier effect on reducing the risk of new-onset AF.

Prevalence of glucose metabolism disorders and its association with left atrial remodelling before and after catheter ablation in patients with atrial fibrillation

AIMS

To investigate the exact prevalence of glucose metabolism disorders, and their impact on left atrial (LA) remodelling and reversibility in patients with atrial fibrillation (AF).

METHODS AND RESULTS

We examined 204 consecutive patients with AF who underwent their first catheter ablation (CA). Oral glucose tolerance test was used to evaluate glucose metabolism disorders in 157 patients without known diabetes mellitus (DM). Echocardiography was performed before and 6 months after CA. Oral glucose tolerance test identified abnormal glucose metabolism in 86 patients [11 with newly diagnosed DM, 74 with impaired glucose tolerance (IGT) and 1 with impaired fasting glucose (IFG)]. Ultimately, 65.2% of patients had abnormal glucose metabolism. Diabetes mellitus group had the worst LA reservoir strain and LA stiffness (both P < 0.05), while there was no significant difference in baseline LA parameters between normal glucose tolerance (NGT) group and IGT/IFG group. The prevalence of LA reverse remodelling (≥15% decrease in the LA volume index at 6 months after CA) was significantly higher in NGT group compared with IGT/IFG and DM group (64.1 vs. 38.6 vs. 41.5%, P = 0.006). Both DM and IFG/IGT carry a significant risk of lack of LA reverse remodelling independent of baseline LA size and AF recurrence.

CONCLUSION

Approximately 65% of patients with AF who underwent their first CA had abnormal glucose metabolism. Patients with DM had significantly impaired LA function compared with non-DM patients. Impaired glucose tolerance/IFG as well as DM carries significant risk of unfavourable LA reverse remodelling. Our observations may provide valuable information regarding the mechanisms and therapeutic strategies of glucose metabolism-related AF.

Silent atrial fibrillation detected by home-monitoring: Cardiovascular disease and stroke prevention in patients with diabetes

OBJECTIVE

Patients with silent and undiagnosed paroxysmal atrial fibrillation and flutter (AF) have increased risk of ischemic stroke. Patients with diabetes have a higher risk of both AF and ischemic stroke compared to patients without diabetes. Our aim was to investigate the prevalence of silent AF in patients with diabetes in an outpatient cohort and to identify the possible risk factors associated with AF.

RESEARCH DESIGN AND METHODS

This prospective observational study was performed in the outpatient diabetes clinic at a single University Hospital. We included 217 patients with type 1 or type 2 diabetes with at least one additional risk factor from the CHA₂DS₂VASc Score for Stroke Risk Assessment in Atrial Fibrillation. The primary outcome was prevalence of AF, with a duration of at least 30 s, recorded by a seven-day home-monitor, external loop recorder (ELR) in comparison to a standard resting ECG. Seventeen patients were excluded due to premature removal of the device.

RESULTS

In the final cohort of 200 patients the majority were male (58.5%) with a mean age of 66 ± 0.7 years. The mean BMI was 29 ± 6 and patients had a mean diabetes history of 23 ± 14 years with the majority diagnosed with type 2 diabetes (59%). Comorbidity was common with hypertension in 86%, and dyslipidemia in 80%. The total prevalence of silent AF [n = 20 (10%)] or flutter [n = 1 (0.5%)] was 10.5% using the ELR compared to a 0.0% detection-rate in the standard ECG method (p < 0.001). Higher age, male gender, albuminuria, and elevated systolic blood pressure were associated with AF in univariate analyses, but only age [OR 1.14 (95% CI = 1.00-2.04) (p = 0.048)], male gender [OR 4.9 (95% CI = 1.30-18.65) (p = 0.019)] and albuminuria [OR 2.7 (95% CI =1.08-6.98) (p = 0.034) were independently associated with AF. Mean CHA₂DS₂VASc Score was ≥2 (4.1, SD ± 1.6), and patients with AF were referred to further cardiac evaluation.

CONCLUSION

Undiagnosed, silent AF is common in high-risk cohort with a long history of diabetes followed in a University Hospital outpatient clinic. Non-invasive monitoring with ELR enhances detection of AF and identifies candidates for early anticoagulation treatment with the possible effect of stroke prevention.

Macrovascular Complications of Type 2 Diabetes Mellitus

BACKGROUND

Type 2 diabetes mellitus (T2DM) has emerged as a pandemic. It has different complications, both microvascular and macrovascular.

OBJECTIVE

The purpose of this review is to summarize the different types of macrovascular complications associated with T2DM.

METHODS

A comprehensive review of the literature was performed to identify clinical studies, which determine the macrovascular complications associated with T2DM.

RESULTS

Macrovascular complications of T2DM include coronary heart disease, cardiomyopathy, arrhythmias and sudden death, cerebrovascular disease and peripheral artery disease. Cardiovascular disease is the primary cause of death in diabetic patients. Many clinical studies have shown a connection between T2DM and vascular disease, but almost always other risk factors are present in diabetic patients, such as hypertension, obesity and dyslipidaemia.

CONCLUSION

T2DM causes a variety of macrovascular complications through different pathogenetic pathways that include hyperglycaemia and insulin resistance. The association between T2DM and cardiovascular disease is clear, but we need more clinical studies in order to identify the pure effect of T2DM.

Dose-response analysis between hemoglobin A1c and risk of atrial fibrillation in patients with and without known diabetes

Background

The relationship between serum hemoglobin A1c (HbA1c) and atrial fibrillation (AF) or postoperative AF (POAF) in coronary artery bypass (CABG) patients is still under debate. It is also unclear whether there is a dose-response relationship between circulating HbA1c and the risk of AF or POAF.

Methods and results

The Cochrane Library, PubMed, and EMBASE databases were searched. A robust-error meta-regression method was used to summarize the shape of the dose-response relationship. The RR and 95%CI were using a random-effects model. In total, 14 studies were included, totaling 17,914 AF cases among 352,325 participants. The summary RR per 1% increase in HbA1c was 1.16 (95% CI: 1.07–1.27). In the subgroup analysis, the summary RR was 1.13 (95% CI: 1.08–1.19) or 1.12 (95% CI: 1.05–1.20) for patients with diabetes or without known diabetes, respectively. The nonlinear analysis showed a nonlinear (P_nonlinear = 0.04) relationship between HbA1c and AF, with a significantly increased risk of AF if HbA1c was over 6.3%. However, HbA1c (per 1% increase) was not associated with POAF in patients with diabetes (RR: 1.13, P = 0.34) or without known diabetes (RR: 0.91, P = 0.37) among patients undergoing CABG.

Conclusion

Our results suggest that higher HbA1c was associated with an increased risk of AF, both in diabetes and in without diabetes or with unknown diabetes. However, no association was found between HbA1c and POAF in patients undergoing CABG. Further prospective studies with larger population sizes are needed to explore the association between serum HbA1c level and the risk of POAF.

Glycemic control is associated with atrial structural remodeling in patients with type 2 diabetes

Background

Diabetes mellitus (DM) has been demonstrated to be a strong risk factor for development and perpetuation of atrial fibrillation (AF). However, how DM and glycemic control affect the pathogenesis of AF has not been sufficiently investigated, especially for the atrial structural remodeling.

Methods

A total of 86 patients undergoing coronary artery bypass graft surgery were enrolled in this study, with atrium sample collected in the operation. The patients were divided into the DM group (n = 40) and the control group (n = 46) accordingly. Demographics, clinical data were collected and compared. Echocardiography, Masson staining and Western blotting were conducted to evaluate atrial structural remodeling.

Results

There was no significant difference between the two groups in baseline characteristics (all P > 0.05). Fast blood glucose and HbA1c of DM group were significantly higher than the control group (P < 0.001). Echocardiography results demonstrated that the left atrium diameter (LAD) and left atrium volume index (LAVI) of DM group was significantly higher than the control group (P < 0.001). Masson staining showed that the collagen volume fraction (CVF), a quantitative indicator of fibrosis, was significantly higher in DM patients (P = 0.03). Western blot results indicated that the Collagen I of DM group was more expressed in the DM group than the control group (P < 0.001). Univariate linear regression revealed that the HbA1c level was significantly associated with both LAD (Y = 1.139X + 25.575, P < 0.001, R² = 0.291) and CVF (Y = 0.444X + 29.648, P = 0.009, R² = 0.078).

Conclusions

DM was associated with atrial structural remodeling, including atrium enlargement and atrial fibrosis, which might be attributed to poor glycemic control.

The continuous challenge of antithrombotic strategies in diabetes: focus on direct oral anticoagulants

Direct oral anticoagulants (DOACs) include dabigatran, which inhibits thrombin, and apixaban, edoxaban, and rivaroxaban, which inhibit factor Xa. They have been extensively studied in large trials involving patients affected by the most common cardiovascular diseases. As the presence of diabetes leads to peculiar changes in primary and secondary hemostasis, in this review we highlight the current evidence regarding DOAC use in diabetic patients included in the majority of recently conducted studies. Overall, in trials involving patients with atrial fibrillation, data seem to confirm at least a similar efficacy and safety of DOACs compared to warfarin in patients with or without diabetes. Furthermore, in diabetic patients, treatment with DOACs is associated with a significant relative reduction in vascular death compared to warfarin. In trials enrolling patients undergoing percutaneous coronary intervention, results concerning bleeding events are consistent in patients with or without diabetes. With regards to the COMPASS study, in patients with diabetes (n = 10,241), addition of rivaroxaban 2.5 mg to aspirin resulted in a significantly lower incidence of major adverse cardiovascular events (HR 0.74, 95% CI 0.61-0.90; interaction p = 0.68) with higher rates of major bleeding expected (HR 1.70, 95% CI 1.25-2.31). The 3287 patients with peripheral artery disease and diabetes receiving rivaroxaban plus aspirin had a twofold higher absolute reduction in the composite endpoint (cardiovascular death, myocardial infarction, and stroke) than patients without diabetes. Finally, we report the involvement of cytochromes or P-glycoprotein on the metabolism of the most commonly prescribed glucose-lowering drugs. No clinically relevant interactions are expected during the concomitant use of DOACs and anti-diabetic agents.

The impact of body weight and diabetes on new-onset atrial fibrillation: a nationwide population based study

Background

Being obese or underweight, and having diabetes are important risk factors for new-onset atrial fibrillation (AF). However, it is unclear whether there is any interaction between body weight and diabetes in regard to development of new-onset AF. We aimed to evaluate the role of body weight status and various stage of diabetes on new-onset AF.

Methods

This was a nationwide population based study using National Health Insurance Service (NHIS) data. A total of 9,797,418 patients who underwent national health check-ups were analyzed. Patients were classified as underweight [body mass index (BMI) < 18.5], normal reference group (18.5 ≤ BMI < 23.0), upper normal (23.0 ≤ BMI < 25.0), overweight (25.0 ≤ BMI < 30.0), or obese (BMI ≥ 30.0) based on BMI. Diabetes were categorized as non-diabetic, impaired fasting glucose (IFG), new-onset diabetes, diabetes < 5 years, and diabetes ≥ 5 years. Primary outcome end point was new-onset AF. New-onset AF was defined as one inpatient or two outpatient records of International Classification of Disease, Tenth Revision (ICD-10) codes in patients without prior AF diagnosis.

Results

During 80,130,161 patient*years follow-up, a total of 196,136 new-onset AF occurred. Obese [hazard ration (HR) = 1.327], overweight (HR = 1.123), upper normal (HR = 1.040), and underweight (HR = 1.055) patients showed significantly increased risk of new-onset AF compared to the normal reference group. Gradual escalation in the risk of new-onset AF was observed along with advancing diabetic stage. Body weight status and diabetes were independently associated with new-onset AF and at the same time, had synergistic effects on the risk of new-onset AF with obese diabetic patients having the highest risk (HR = 1.823).

Conclusions

Patients with obesity, overweight, underweight, and diabetes had significantly increased risk of new-onset AF. Body weight status and diabetes had synergistic effects on the risk of new-onset AF. The risk of new-onset AF increased gradually with advancing diabetic stage. This study suggests that maintaining optimal body weight and glucose homeostasis might prevent new-onset AF.

Regulating the Warburg effect on metabolic stress and myocardial fibrosis remodeling and atrial intracardiac waveform activity induced by atrial fibrillation

Atrial fibrillation (AF) is associated with metabolic stress and induces myocardial fibrosis reconstruction by increasing glycolysis. One goal in the treatment of paroxysmal AF (p-AF) is to improve myocardial fibrosis reconstruction and myocardial metabolic stress caused by the Warburg effect. Adopted male canine that rapid right atrial pacing (RAP) for 6 days to establish a p-AF model. The canines were pre-treated with phenylephrine (PE) or dichloroacetic acid (DCA) before exposure to p-AF or non-p-AF. P-wave duration (P_max), minimum P-wave duration (P_min), P wave dispersion (PWD), atrial effective refractory period (AERP) and AERP dispersion (AERPd) were measured in canine atrial cardiomyocytes. Pyruvate dehydrogenase kinase-1 (PDK-1), PDK-4, lactate dehydrogenase A (LDHA), pyruvate dehydrogenase (PDH), citrate synthase (CS), isocitrate dehydrogenase (IDH), and matrix metalloproteinase 9 (MMP-9) were evaluated by western blotting and reverse transcription polymerase chain reaction (RT-PCR), content of adenosine monophosphate (AMP), adenosine triphosphate (ATP), lactic acid and glycogen, and activity of LDHA, PDK-1 and PDK-4 were evaluated by enzyme-linked immunosorbent assay (ELISA), myocardial tissue glycogen content was evaluated by PAS, myocardial fibrosis remodeling was evaluated by hematoxylin and eosin (H&E) and Masson staining. Our findings demonstrated that p-AF increases the Warburg effect-related metabolic stress and myocardial fibrosis remodeling by increasing the expression and activity of PDK-1, PDK-4, and LDHA, content of AMP and lactic acid, and the ratio of AMP/ATP and decreasing the expression of PDH, CS, and IDH, and glycogen content. In addition, p-AF can induce cardiomyocyte fibrosis remodeling and increase MMP-9 expression, and p-AF also increases atrial intracardiac waveform activity by prolonging P_max, P_min, PWD, and AERPd and shortening AERP. PDK isoforms agonists (PE) produce a similar p-AF pathological effect and can produce synergistic effects with p-AF, further increasing Warburg effect-related metabolic stress, myocardial fibrosis remodeling, and atrial intracardiac waveform activity. In contrast, the use of PDK-specific inhibitors (DCA) completely reverses these pathophysiological changes induced by p-AF. We demonstrate that p-AF can induce the Warburg effect in canine atrial cardiomyocytes and significantly improve p-AF-induced metabolic stress, myocardial fibrosis remodeling, and atrial intracardiac waveform activity by inhibiting the Warburg effect.

Clinical implication of an impaired fasting glucose and prehypertension related to new onset atrial fibrillation in a healthy Asian population without underlying disease: a nationwide cohort study in Korea

Aims

For healthy populations without comorbidities, whether prehypertension and impaired fasting glucose (IFG) are associated with new onset atrial fibrillation (AF) is not well known.

Methods and results

We included 366 507 subjects (age ≥20 years) not diagnosed with non-valvular AF from the Korean National Health Insurance Service-National Sample Cohort (NHIS-NSC) from 2003 to 2008. In total, 139 306 subjects diagnosed with AF-related comorbidities were excluded, and a 227 102 healthy population was followed up until 2013. The body mass index (BMI), blood pressure (BP), and fasting blood glucose (BG) level were acquired during National health check-ups. Subjects with IFG [hazard ratio (HR) 1.16, P = 0.017] had a higher AF risk and the diastolic BP (HR 1.11, P = 0.045) was a stronger indicator for an AF incidence than the systolic BP. After dividing the subjects into two mutually exclusive groups, AF incidence was increased dramatically by the combination effect of both prehypertension and an IFG in BMI <25 kg/m2 group, but, in BMI ≧25 kg/m2 group, did not show this tendency. An IFG related to AF risk was more prominent in the BMI <25 kg/m2 population (HR 1.18, P = 0.025) than those with a BMI ≥25 kg/m2, and subjects with both an IFG and prehypertension had a greater AF risk (HR 1.27, P = 0.016) than those without.

Conclusion

Even in a healthy Asian populations without comorbidities, prehypertension and IFG were important risk factors of AF. Specifically, when prehypertension, including systolic and diastolic BPs, was finally combined with the IFG, the risk of new onset AF was increased especially in the BMI <25 kg/m2 group.

The association between insulin resistance and atrial fibrillation: A cross-sectional analysis from SPRINT (Systolic Blood Pressure Intervention Trial)

It is unclear whether metabolic syndrome (MetS) is associated with atrial fibrillation (AF) in an older population with greater cardiovascular risk, including those with chronic kidney disease. The authors investigated the association between MetS and AF in participants in SPRINT (Systolic Blood Pressure Intervention Trial). MetS was defined based on the Modified Third National Cholesterol Education Program. The baseline prevalence rate for MetS was 55%, while 8.2% of the participants had AF. In multivariate regression analyses, AF was not associated with presence of MetS in either chronic kidney disease or non-chronic kidney disease subgroups. Age, race, history of cardiovascular diseases, decreased triglycerides, decreased pulse pressure, and albuminuria remained significantly associated with AF risk. In contrast to the general population, MetS was not associated with AF in the older population with increased cardiovascular risk studied in SPRINT.

Serum glycated hemoglobin level as a predictor of atrial fibrillation: A systematic review with meta-analysis and meta-regression

Background and Aim

Glycated hemoglobin (HbA1c) is a long-term measure of glucose control. Although recent studies demonstrated a potential association between HbA1c levels and the risk of atrial fibrillation (AF), the results have been inconsistent. The aim of this meta-analysis is to evaluate the utility of HbA1c level in predicting AF.

Methods

PubMed and the Cochrane Library databases were searched for relevant studies up to March 2016. Prospective cohort studies and retrospective case-control studies were included. Relative risk (RR) or odds ratio (OR) with 95% confidence intervals (CIs) of AF development were determined for different HbA1c levels. The random effect model was conducted according to the test of heterogeneity among studies. Subgroup analyses and meta-regression models were carried out to identify potential sources of heterogeneity.

Results

Eight prospective cohort studies with 102,006 participants and 6 retrospective case-control studies with 57,669 patients were finally included in the meta-analysis. In the primary meta-analysis, HbA1c levels were not associated with an increased risk of AF whether as a continuous (RR, 1.06; 95% CI, 0.96–1.18) or categorical variable (RR, 0.99; 95% CI, 0.83–1.18). Nevertheless, prospective studies showed about 10% increased risk of AF with elevated HbA1c levels both as a continuous (RR, 1.11; 95% CI, 1.06–1.16) and as a categorical variable (RR, 1.09; 95% CI, 1.00–1.18). In subgroup analyses, pooled results from studies with longer follow-up durations, published after 2012, aged < 63 years, with exclusion of cardiac surgery patients demonstrated an increased risk of AF for every 1% increase in HbA1c levels, while studies conducted in the United States with longer follow-up (more than 96 months), larger sample size and higher quality score (≥6) showed an increased risk of AF for higher HbA1c level as a categorical variable.

Conclusions

Elevated serum HbA1c levels may be associated with an increased risk of AF, but further data are needed. Serum HbA1c levels might be considered as a potential biomarker for prediction of AF.

QTc interval predicts outcome of catheter ablation in paroxysmal atrial fibrillation patients with type 2 diabetes mellitus

Catheter ablation has been recommended as a treatment option for paroxysmal atrial fibrillation (PAF) patients complicated with type 2 diabetes mellitus (T2DM). PAF patients with T2DM have a higher recurrence rate after catheter ablation. Prolongation of corrected QT (QTc) interval has been linked to poor outcomes in T2DM patients. Whether the abnormal QTc interval is associated with the ablation outcome in the PAF patients with T2DM remains unknown. In this study, 134 PAF patients with T2DM undergoing primary catheter ablation were retrospectively enrolled. Pre-procedural QTc interval was corrected by using the Bazett's formula. Cox proportional hazards models were constructed to assess the relationship between QTc interval and the recurrence of AF. After a 29.1-month follow-up period, 61 patients experienced atrial tachyarrhythmia recurrence. Recurrent patients had a longer QTc interval than non-recurrent patients (425.2±21.5 ms vs. 414.1±13.4 ms, P=0.002). Multivariate Cox regression analysis revealed that QTc interval [hazard ratio (HR)=1.026, 95% confidence interval (CI) 1.012-1.040, P=0.005] and left atrial diameter (LAD) (HR=1.125, 95% CI 1.062-1.192, P=0.003) were independent predictors of recurrent atrial tachyarrhythmia. Receiver operating characteristic analysis demonstrated that the cut-off value of QTc (418 ms) predicted arrhythmia recurrence with a sensitivity of 55.7% and a specificity of 69.9%. A combination of LAD and QTc was more effective than LAD alone (P<0.001) in predicting arrhythmia recurrence after the procedure. QTc interval could be used as an independent predictor of arrhythmia recurrence in T2DM patients undergoing AF ablation, thus providing a simple method to identify those patients who likely have a better outcome following the procedure.

The relationship between HbA1c & atrial fibrillation after off-pump coronary artery bypass surgery in diabetic patients

Objective:

Diabetes mellitus is recognized as a risk factor for mortality and morbidity after coronary bypass grafting. We aimed to determine the association between preoperative hemoglobin HbA1c and AF after isolated off-pump coronary bypass grafting (OPCAB).

Methods:

The seventy-two diabetic patients undergoing isolated off-pump coronary bypass grafting were retrospectively analyzed for AF. They were divided into; Low (4.8–5.4%), Medium (5.5–8%) and High (8.1–11.5%) groups. The three groups were compared with respect to demographic, echocardiographic, intraoperative and postoperative clinical characteristics correlation.

Results:

Three patients died during postoperative period. AF occurred in 12 patients (16.6%) after surgery. The incidence of postoperative AF was 15.3% in the lower, 4.4% middle and 57.1% upper group. There was statistically significant correlation between preoperative HbA1C and preoperative stroke, preoperative MI history, Left atrial (LA) size, preoperative levosimendan, preoperative clopidogrel, postoperative AF, postoperative dopamine and dobutamine use, IABP, duration of extubation time, 24-hour chest tube drainage, duration of ICU and hospital mortality. Univariate logistic regression analysis showed significant correlation between postoperative AF and variables like preoperative HbA1c levels, LVEF<30%, history of preoperative MI, preoperative use of levosimendan, preoperative use of clopidogrel, postoperative dopamine, dobutamine adrenaline use, left atrium size, 24-hour chest tube drainage and length of stay in the intensive care unit.

Conclusion:

Preoperative HbA1c levels could predict the occurrence of postoperative AF in diabetic patients and may entail to administer protective strategies.

Ryanodine receptor phosphorylation by CaMKII promotes spontaneous Ca(2+) release events in a rodent model of early stage diabetes: The arrhythmogenic substrate

BACKGROUND

Heart failure and arrhythmias occur more frequently in patients with type 2 diabetes (T2DM) than in the general population. T2DM is preceded by a prediabetic condition marked by elevated reactive oxygen species (ROS) and subclinical cardiovascular defects. Although multifunctional Ca2+ calmodulin-dependent protein kinase II (CaMKII) is ROS-activated and CaMKII hyperactivity promotes cardiac diseases, a link between prediabetes and CaMKII in the heart is unprecedented.

OBJECTIVES

To prove the hypothesis that increased ROS and CaMKII activity contribute to heart failure and arrhythmogenic mechanisms in early stage diabetes.

METHODS-RESULTS

Echocardiography, electrocardiography, biochemical and intracellular Ca2+ (Ca2+i) determinations were performed in fructose-rich diet-induced impaired glucose tolerance, a prediabetes model, in rodents. Fructose-rich diet rats showed decreased contractility and hypertrophy associated with increased CaMKII activity, ROS production, oxidized CaMKII and enhanced CaMKII-dependent ryanodine receptor (RyR2) phosphorylation compared to rats fed with control diet. Isolated cardiomyocytes from fructose-rich diet showed increased spontaneous Ca2+i release events associated with spontaneous contractions, which were prevented by KN-93, a CaMKII inhibitor, or addition of Tempol, a ROS scavenger, to the diet. Moreover, fructose-rich diet myocytes showed increased diastolic Ca2+ during the burst of spontaneous Ca2+i release events. Mice treated with Tempol or with sarcoplasmic reticulum-targeted CaMKII-inhibition by transgenic expression of the CaMKII inhibitory peptide AIP, were protected from fructose-rich diet-induced spontaneous Ca2+i release events, spontaneous contractions and arrhythmogenesis in vivo, despite ROS increases.

CONCLUSIONS

RyR2 phosphorylation by ROS-activated CaMKII, contributes to impaired glucose tolerance-induced arrhythmogenic mechanisms, suggesting that CaMKII inhibition could prevent prediabetic cardiovascular complications and/or evolution.

Elevated glycated hemoglobin levels may increase the risk of atrial fibrillation in patients with diabetes mellitus

BACKGROUND

As the most common cardiac arrhythmia, atrial fibrillation (AF) is always accompanied with various complications if without detection and treatment timely. Blood-based pleiotropic molecule biomarkers have now been popularly applied in clinical detection. We hence performed this meta-analysis to evaluate the correlation of serum glycated hemoglobin (HbA1c) levels with the risk of AF in patients with diabetes mellitus (DM).

METHODS

Covering myriads of computerized databases, we identified potential relevant studies for statistical analysis. We used a standard reporting form to extract data from each included study. Newcastle-Ottawa Scale (NOS) criteria was used for methodological quality assessment. Statistical analyses were conducted with the STATA statistical software.

RESULTS

Six cohort studies in full text fulfilled our inclusion criteria, and following overestimation indicated that serum levels of HbA1c in DM patients with AF was higher than that in DM patients without AF (SMD = 0.67, 95% CI: 0.39-0.94, P < 0.001). Subgroup analyses by sample size and detection method implicated that elevated serum HbA1c levels exhibited significant correlations with an increased risk of AF in DM patients in the large-size subgroup (n ≥ 200), the small-size subgroup (n < 200), the high performance liquid chromatography (HPLC) subgroup and the non-HPLC subgroup (Large-size: SMD = 0.70, 95% CI: 0.38-1.03, P < 0.001; Small-size: SMD = 0.64, 95% CI: 0.09-1.19, P = 0.023; HPLC: SMD = 0.81, 95% CI: 0.49-1.12, P < 0.001; Non-HPLC: SMD = 0.36, 95% CI: 0.04-0.68, P = 0.029; respectively).

CONCLUSION

Elevated serum HbA1c levels may be associated with an increased risk of AF in DM patients, possibly reflecting that serum HbA1c level might be a potential biomarker in the prediction of AF in DM patients.

Clinical characteristics and impact of diabetes mellitus on outcomes in patients with nonvalvular atrial fibrillation

PURPOSE

Studies have shown that diabetes mellitus (DM) is a risk factor for cardiovascular disease, including atrial fibrillation (AF); however, the clinical characteristics and prognostic impact of DM in patients with nonvalvular AF have not been well understood in China.

MATERIALS AND METHODS

Included were 1644 consecutive patients with nonvalvular AF. Endpoints included all-cause mortality, cardiovascular mortality, stroke, major bleeding, and combined endpoint events (CEE) during a 1-year follow-up.

RESULTS

The prevalence of DM was 16.8% in nonvalvular AF patients. Compared with non-diabetic AF patients, diabetic AF patients were older and tended to coexist with other cardiovascular diseases. Most patients with DM (93.5%) were eligible for anticoagulation, as determined by CHADS2 scores. However, only 11.2% of patients received anticoagulation. During a 1-year follow-up, the all-cause mortality and CEE rate in the DM group were significantly higher than those of the non-DM group, while the incidence of stroke was comparable. After multivariate adjustments, DM was still an independent risk factor for 1-year all-cause mortality [hazard ratio (HR)=1.558; 95% confidence interval (CI) 1.126-2.156; p=0.007], cardiovascular mortality (HR=1.615; 95% CI 1.052-2.479; p=0.028), and CEE (HR=1.523; 95% CI 1.098-2.112; p=0.012), yet not for stroke (HR=1.119; 95% CI 0.724-1.728; p=0.614).

CONCLUSION

DM is a common morbidity coexisting with nonvalvular AF and is associated with an increased risk of 1-year all-cause mortality, cardiovascular mortality, and CEE. However, no increased risk of stroke was found during a 1-year follow-up in patients with AF and DM.

Oxidative stress as a mechanism of added sugar-induced cardiovascular disease

Added sugars comprising of table sugar, brown sugar, corn syrup, maple syrup, honey, molasses, and other sweeteners in the prepared processed foods and beverages have been implicated in the pathophysiology of cardiovascular diseases. This article deals with the reactive oxygen species (ROS) as a mechanism of sugar-induced cardiovascular diseases. There is an association between the consumption of high levels of serum glucose with cardiovascular diseases. Various sources of sugar-induced generation of ROS, including mitochondria, nicotinamide adenine dinucleotide phosphate-oxidase, advanced glycation end products, insulin, and uric acid have been discussed. The mechanism by which ROS induce the development of atherosclerosis, hypertension, peripheral vascular disease, coronary artery disease, cardiomyopathy, heart failure, and cardiac arrhythmias have been discussed in detail. In conclusion, the data suggest that added sugars induce atherosclerosis, hypertension, peripheral vascular disease, coronary artery disease, cardiomyopathy, heart failure, and cardiac arrhythmias and that these effects of added sugars are mediated through ROS.

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.

Mechanism of and therapeutic strategy for atrial fibrillation associated with diabetes mellitus

Diabetes mellitus (DM) is one of the most important risk factors for atrial fibrillation (AF) and is a predictor of stroke and thromboembolism. DM may increase the incidence of AF, and when it is combined with other risk factors, the incidence of stroke and thromboembolism may also be higher; furthermore, hospitalization due to heart failure appears to increase. Maintenance of well-controlled blood glucose and low levels of HbA1c in accordance with guidelines may decrease the incidence of AF. The mechanisms of AF associated with DM are autonomic remodeling, electrical remodeling, structural remodeling, and insulin resistance. Inhibition of the renin-angiotensin system is suggested to be an upstream therapy for this type of AF. Studies have indicated that catheter ablation may be effective for AF associated with DM, restoring sinus rhythm and improving prognosis. Catheter ablation combined with hypoglycemic agents may further increase the rate of maintenance of sinus rhythm and reduce the need for reablation.

Poor glycaemic control and arrhythmias

OBJECTIVE

To evaluate number, type, and complexity of arrhythmias in diabetics compared with controls and, among diabetics, comparing good glycaemic control (GGC) and poor glycaemic control (PGC) patients.

METHODS

We compared Ambulatory Electrocardiogram recordings of 92 diabetics and 100 controls. The glycaemic profile of 50 diabetics, taken the same day as the Ambulatory ECG recording, was subdivided into GGC (gluco-stick mean values between 100 and 140 mg/dL) or PGC (gluco-stick values ≤99 mg/dL in 3-of-4 daily determination or gluco-stick values ≥140 mg/dL in 3-of-4 daily determination).

RESULTS

Diabetics show a higher prevalence of either ventricular ectopic beats (VEBs) (93.47% vs. 82% controls, p < 0.05) and heart rate (both in sinus rhythm and in atrial fibrillation) (98.35 ± 10 beats/min in diabetics vs. 78.10 ± 8.1 in controls, p < 0.001). Moreover, diabetics with PGC show either a higher prevalence of VEBs (96.42% vs 77.27% in GGC, p < 0.05) and of supraventricular ectopic beats (SVEBs) (96.42% vs. 68.18 in GGC, p < 0.05); furthermore, diabetics with PGC show more severe and complex atrial and ventricular arrhythmias (SVEBs 32.14% vs 0%, p < 0.05; VEBs 39.28% vs 9.09%, p < 0.05).

CONCLUSIONS

The analysis of our sample shows that the arrhythmogenic condition is not only provided from diabetic condition per se but it is enhanced in PGC. Infact PGC patients showed higher number of VEBs, often polymorphic, expression of more severe arrhythmic and cardiovascular outcome. This could be partially explained by hyperactivation of autonomic nervous system during metabolic stress (which increases mean heart rate). Moreover more severe diabetic patients may present coronary microangiopathy that can further explain their arrhythmogenic tendency.

Atrial fibrillation and diabetes mellitus. Correlation, co-existence, and coagulation therapy

Epidemiological studies have reported on the association between diabetes mellitus (DM) and subsequent risk of atrial fibrillation (AF) with inconsistent results. Individuals with DM present with an increased risk (approximate 40%) of subsequent AF compared with unaffected individuals, but the mechanisms underlying the relationship between DM and AF remains speculative. Both entities share common risk factors and, thus, seem to be closely associated with each other. Obviously, the quality of glycemic control is directly related with the risk for AF; the risk is higher with longer duration of treated diabetes and poorer glycemic control. Future research should identify approaches to reduce the risk of AF in people with diabetes by means of consequent screening and anti-coagulation therapy.

Association of the metabolic syndrome with atrial fibrillation among United States adults (from the REasons for Geographic and Racial Differences in Stroke [REGARDS] Study)

Metabolic syndrome (MS) and atrial fibrillation (AF) are associated with increased cardiovascular disease morbidity and mortality. This analysis evaluated the association between MS and AF in the REasons for Geographic and Racial Differences in Stroke (REGARDS) study. MS was defined using criteria recommended in the joint interim statement from several international societies. AF was defined by electrocardiogram (ECG) and/or self-report and by ECG alone. In patients with 0, 1, 2, 3, 4, and 5 MS components, prevalences of AF by ECG and/or self-report were 5.5%, 7.7%, 8.2%, 9.2%, 9.6%, and 11.5%, respectively (p for trend <0.001). After multivariable adjustment, each MS component except serum triglycerides was significantly associated with AF. The multivariable-adjusted odds ratio for AF, defined by ECG and/or or self-reported history, comparing those with to those without MS was 1.20 (95% confidence interval 1.10 to 1.29). Results were consistent when AF was defined by ECG alone (odds ratio 1.15, 95% confidence interval 0.92 to 1.39). In conclusion, MS is associated with an increased prevalence of AF. Further studies investigating a potential mechanism for this excess risk are warranted.

Meta-analysis of cohort and case-control studies of type 2 diabetes mellitus and risk of atrial fibrillation

Atrial fibrillation (AF) is 1 of the most clinically diagnosed cardiac disturbances but little is known about its risk factors. Previous epidemiologic studies have reported on the association between diabetes mellitus (DM) and subsequent risk of AF, with inconsistent results. The aim of this study was to conduct a meta-analysis of published studies to reliably determine the direction and magnitude of any association between DM and AF. A systematic review and meta-analysis was conducted. PubMed and EMBASE were searched to identify prospective cohort and case-control studies that had reported on the association between DM and other measurements of glucose homeostasis with incident AF by April 2010. Studies conducted in primarily high-risk populations and participants in randomized controlled trials were excluded. Seven prospective cohort studies and 4 case-control studies with information on 108,703 cases of AF in 1,686,097 subjects contributed to this analysis. The summary estimate indicated that patients with DM had an approximate 40% greater risk of AF compared to unaffected patients (relative risk [RR] 1.39, 95% confidence interval [CI] 1.10 to 1.75, p for heterogeneity <0.001). After correcting for publication bias, the RR was 1.34 (1.07 to 1.68). Studies that had adjusted for multiple risk factors reported a smaller effect estimate compared to age-adjusted studies (RR 1.24, 95% CI 1.06 to 1.44, vs 1.70, 1.29 to 2.22, p for heterogeneity = 0.053). The population-attributable fraction of AF owing to DM was 2.5% (95% CI 0.1 to 3.9). In conclusion, DM is associated with an increased risk of subsequent AF but the mechanisms that may underpin the relation between DM and AF remain speculative.

Idiopathic reactive hypoglycaemia - prevalence and effect of fibre on glucose excursions

BACKGROUND

Idiopathic reactive hypoglycaemia (IRH) is a condition characterized by aggravated postprandial glucose excursions in otherwise healthy individuals. We investigated its prevalence and the impact of fibre diet supplementation.

METHODS

First, IRH prevalence was assessed in 362 subjects without a diagnosis of abnormal glucose metabolism through an oral glucose tolerance test (OGTT). IRH was defined by 1 h- or 2 h-glucose ≤3.9 mmol/L or 1 h- or 2 h-glucose < fasting glucose. Second, in a cross-over trial we evaluated effects of 2 weeks with, and without, 20 g fibre (fructose- oligosaccharides) diet supplementation in subjects with IRH. At the end of each 2-week cycle we analysed fasting biomarker levels and conducted a 4 h-OGTT.

RESULTS

IRH was found in 12.4% and a normal glucose tolerance in 56.4% of the participants. The IRH group was characterized by higher fasting (5.3 vs. 5.2 mmol/L, p < 0.05) but lower 2 h- (4.4 vs. 6.5 mmol/L, p < 0.01) glucose levels, whereas age (68 ± 10 vs. 70 ± 9 years) and BMI (24.7 ± 3.3 vs 25.0 ± 3.5 kg/m(2)) were similar. The 2-week fibre diet-supplementation (n = 12, age 56 ± 8 years, 6 females, BMI 25.0 ± 2.9 kg/m(2)) improved both the reactive glucose pattern during the 4 h-OGTT (significantly increased late-onset glucose nadirs and reduced the frequency of glucose ≤3.9 mmol/L [21 to 11, p = 0.04]) and reduced fasting plasma glucose (5.4 ± 0.6 to 5.1 ± 0.5 [p < 0.05]) and total cholesterol (5.3 ± 1.1 to 4.9 ± 1.1 mmol/L [p < 0.04]).

CONCLUSIONS

A reactive glucose pattern following intake of a high glycaemic load is relatively prevalent and this phenomenon could be modulated by dietary fibre supplementation.

Atrial substrate properties and outcome of catheter ablation in patients with paroxysmal atrial fibrillation associated with diabetes mellitus or impaired fasting glucose

Diabetes mellitus has been reported to be an independent risk factor of atrial fibrillation (AF). The present study investigated the atrial substrate properties and clinical outcome of catheter ablation in patients with paroxysmal AF and abnormal glucose metabolism. A total of 228 patients with paroxysmal AF who had undergone catheter ablation for the first time were enrolled. An abnormal glucose metabolism (n = 65) was defined as diabetes mellitus or an impaired fasting glucose. We analyzed the clinical and electrophysiologic characteristics in, and the clinical outcome of, patients with AF with and without an abnormal glucose metabolism. The right atrial (107.2 ± 15.4 vs 96.0 ± 16.5 ms, p < 0.001) and left atrial (108.4 ± 22.3 vs 94.0 ± 17.5 ms, p < 0.001) total activation times were significantly longer in the patients with AF and an abnormal glucose metabolism than in those without an abnormal metabolism. Furthermore, the right atrial (1.46 ± 0.61 vs 2.00 ± 0.70 mV, p < 0.001) and left atrial (1.48 ± 0.74 vs 2.05 ± 0.78 mV, p < 0.001) bipolar voltages were significantly lower in those with AF and an abnormal glucose metabolism than in those without. The AF recurrence rate was also greater in the patients with an abnormal glucose metabolism (18.5% vs 8.0%, p = 0.022) than in those without. The follow-up duration was 18.8 ± 6.4 months. In conclusion, an abnormal glucose metabolism affects the biatrial substrate properties with an intra-atrial conduction delay, decreased voltage, and greater recurrence rate after catheter ablation.

Diabetes mellitus, glycemic control, and risk of atrial fibrillation

BACKGROUND

Diabetes may be an independent risk factor for atrial fibrillation. However, results from prior studies are in conflict, and no study has examined diabetes duration or glycemic control.

OBJECTIVE

To examine the association of diabetes with risk of atrial fibrillation and to describe risk according to diabetes duration and glycemic control.

DESIGN

A population-based case-control study.

PARTICIPANTS

Within a large, integrated healthcare delivery system, we identified 1,410 people with newly-recognized atrial fibrillation from ICD-9 codes and validated cases by review of medical records. 2,203 controls without atrial fibrillation were selected from enrollment lists, stratified on age, sex, hypertension, and calendar year.

MAIN MEASURES

Information on atrial fibrillation, diabetes and other characteristics came from medical records. Diabetes was defined based on physician diagnoses recorded in the medical record, and pharmacologically treated diabetes was defined as receiving antihyperglycemic medications. Information about hemoglobin A1c levels came from computerized laboratory data.

KEY RESULTS

Among people with atrial fibrillation, 252/1410 (17.9%) had pharmacologically treated diabetes compared to 311/2203 (14.1%) of controls. The adjusted OR for atrial fibrillation was 1.40 (95% CI 1.15-1.71) for people with treated diabetes compared to those without diabetes. Among those with treated diabetes, the risk of developing atrial fibrillation was 3% higher for each additional year of diabetes duration (95% CI 1-6%). Compared to people without diabetes, the adjusted OR for people with treated diabetes with average hemoglobin A1c <or=7 was 1.06 (95% CI 0.74-1.51); for A1c >7 but <or=8, 1.48 (1.09-2.01); for A1c >8 but <or=9, 1.46 (1.02-2.08); and for A1c >9, 1.96 (1.22-3.14).

CONCLUSIONS

Diabetes was associated with higher risk of developing atrial fibrillation, and risk was higher with longer duration of treated diabetes and worse glycemic control. Future research should identify and test approaches to reduce the risk of atrial fibrillation in people with diabetes.