Decreased endogenous secretory RAGE and increased hsCRP levels in serum are associated with atrial fibrillation in patients undergoing coronary angiography

Glycation and Glycosylation in Cardiovascular Remodeling: Focus on Advanced Glycation End Products and O-Linked Glycosylations as Glucose-Related Pathogenetic Factors and Disease Markers

Glycation and glycosylation are non-enzymatic and enzymatic reactions, respectively, of glucose, glucose metabolites, and other reducing sugars with different substrates, such as proteins, lipids, and nucleic acids. Increased availability of glucose is a recognized risk factor for the onset and progression of diabetes-mellitus-associated disorders, among which cardiovascular diseases have a great impact on patient mortality. Both advanced glycation end products, the result of non-enzymatic glycation of substrates, and O-linked-N-Acetylglucosaminylation, a glycosylation reaction that is controlled by O-N-AcetylGlucosamine (GlcNAc) transferase (OGT) and O-GlcNAcase (OGA), have been shown to play a role in cardiovascular remodeling. In this review, we aim (1) to summarize the most recent data regarding the role of glycation and O-linked-N-Acetylglucosaminylation as glucose-related pathogenetic factors and disease markers in cardiovascular remodeling, and (2) to discuss potential common mechanisms linking these pathways to the dysregulation and/or loss of function of different biomolecules involved in this field.

AGE-RAGE Stress in the Pathophysiology of Atrial Fibrillation and Its Treatment

Atrial fibrillation (AF) is the most common of cardiac arrhythmias. Mechanisms such as atrial structural remodeling and electrical remodeling have been implicated in the pathogenesis of AF. The data to date suggest that advanced glycation end products (AGEs) and its cell receptor RAGE (receptor for AGE) and soluble receptor (sRAGE) are involved in the pathogenesis of AF. This review focuses on the role of AGE-RAGE axis in the pathogenesis of AF. Interaction of AGE with RAGE generates reactive oxygen species, cytokines, and vascular cell adhesion molecules. sRAGE is a cytoprotective agent. The data show that serum levels of AGE and sRAGE, and expression of RAGE, are elevated in AF patients. Elevated levels of sRAGE did not protect the development of AF. This might be due to greater elevation of AGE than sRAGE. Measurement of AGE-RAGE stress (AGE/sRAGE) would be appropriate as compared with measurement of AGE or RAGE or sRAGE alone in AF patients. AGE and its interaction with RAGE can induce AF through alteration in cellular protein and extracellular matrix. AGE and its interaction with RAGE induce atrial structural and electrical remodeling. The treatment strategy should be directed toward reduction in AGE levels, suppression of RAGE expression, blocking of binding of AGE to RAGE, and elevation of sRAGE and antioxidants. In conclusion, AGE-RAGE axis is involved in the development of AF through atrial structural and electrical remodeling. The treatment modalities for AF should include lowering of AGE, suppression of RAGE, elevation of sRAGE, and use of antioxidants.

Feasibility of low-dose coronary computed tomographic angiography used in atrial fibrillation patients

OBJECTIVE

The diagnosis of coronary artery disease (CAD) in atrial fibrillation (AF) patients using coronary computed tomography angiography (CCTA) requires a large exposure dosage or repeated examinations. This study evaluates the feasibility of using low-dose CCTA in the double prospectively ECG-triggered high-pitch spiral acquisition mode (Double Flash Spiral mode).

METHODS

Twenty-eight AF patients with suspected CAD were recruited. Double Flash Spiral mode (tube voltage 100 kVp) and iterative reconstruction was used for CCTA examination. Two radiologists cross-evaluated the CCTA image quality. The effective radiation dose was measured for each patient.

RESULTS

Twenty-eight AF patients (10 female, 18 male, mean age 68.8 ± 13.9 y, body mass index 24.3 ± 2.3 kg/cm²) were recruited and 337 artery segments were evaluated. In total, 98.5% (332/337) of the coronary artery segments and 96.4% (27/28) of the AF patients were rated as diagnostically evaluable. Of these 27 diagnosable patients, 17 patients (63%) were diagnosed with multi-vessel stenosis. Besides, 5 of 28 patients (17.9%) have left atrial appendage thrombus. The quality of the integrated image was significantly better than either of the individual first or the second scans, based on segments (P < 0.001) and patients (P < 0.05). The mean effective radiation dose was 1.5 mSv ±0.4 mSv.

CONCLUSIONS

Using the Double Flash Spiral mode at low radiation dose (mean 1.5 mSv), 98.5% of the coronary segments and 96.4% of the scans were of sufficient diagnostic quality.

The Receptor for Advanced Glycation End Products (RAGE) Is Associated with Persistent Atrial Fibrillation

Objective

Upregulation of the receptor for advanced glycation end products (RAGE) has been proposed as a pathophysiological mechanism underlying the development of atrial fibrillation (AF). We sought to investigate if soluble RAGE levels are associated with AF in Caucasian patients.

Methods

Patients (n = 587) were prospectively recruited and serum levels of soluble RAGE (sRAGE) and endogenous secretory RAGE (esRAGE) measured. The patients included 527 with sinus rhythm, 32 with persistent AF (duration >7 days, n = 32) and 28 with paroxysmal AF (duration <7 days, n = 28).

Results

Patients with AF were older and had a greater prevalence of heart failure than patients in sinus rhythm. Circulating RAGE levels were higher in patients with persistent AF [median sRAGE 1190 (724–2041) pg/ml and median esRAGE 452 (288–932) pg/ml] compared with paroxysmal AF [sRAGE 799 (583–1033) pg/ml and esRAGE 279 (201–433) pg/ml, p ≤ 0.01] or sinus rhythm [sRAGE 782 (576–1039) pg/ml and esRAGE 289 (192–412) pg/ml, p < 0.001]. In multivariable logistic regression analysis, independent predictors of persistent AF were age, heart failure, sRAGE [odds ratio 1.1 per 100 pg/ml, 95% confidence interval (CI) 1.0–1.1, p = 0.001] and esRAGE [odds ratio 1.3 per 100 pg/ml, 95% CI 1.1–1.4, p < 0.001]. Heart failure and age were the only independent predictors of paroxysmal AF. In AF patients, sRAGE [odds ratio 1.1 per 100 pg/ml, 95% CI 1.1–1.2, p = 0.007] and esRAGE [odds ratio 1.3 per 100 pg/ml, 95% CI 1.0–1.5, p = 0.017] independently predicted persistent compared with paroxysmal AF.

Conclusions

Soluble RAGE is elevated in Caucasian patients with AF, and both sRAGE and esRAGE predict the presence of persistent AF.

sRAGE, inflammation, and risk of atrial fibrillation: results from the Atherosclerosis Risk in Communities (ARIC) Study

OBJECTIVE

Advanced glycation end products (AGEs) may cause inflammation by binding to their cellular receptors (RAGE). Soluble RAGE (sRAGE) acts as a decoy receptor for AGEs and may prevent inflammation. Chronic low-grade inflammation is a risk factor for cardiovascular disease, including atrial fibrillation (AF).

METHODS

We studied 1,068 participants in a subsample of the Atherosclerosis Risk in Communities (ARIC) Study who had baseline measurements of sRAGE (mean age 56, 60% female, 21% Black). Inflammation was assessed using measurements of high sensitivity C-reactive protein (hsCRP), fibrinogen, gamma-glutamyl transferase (GGT) and white blood cell (WBC) count. AF events were identified using ECG data, hospitalization discharge codes, and linkage to the National Death Index.

RESULTS

Compared to the highest quartile (>1272.4 pg/mL), the lowest quartile of sRAGE (<714 pg/mL) was associated with higher baseline levels of inflammation (hsCRP ≥3 mg/L: OR=2.21 [95% CI 1.41-3.49], fibrinogen ≥400 mg/dL: OR=4.31 [95% CI 1.50-12.41], GGT ≥36 U/L in women and ≥61 U/L in men: OR=5.22 [95% CI 2.66-10.22], WBC >6.2×10⁹/L: OR=2.38 [95% CI 1.52-3.72]). sRAGE was not prospectively associated with 6-year change in inflammatory markers (hsCRP or GGT). There was no significant association of sRAGE and risk of AF (HR 1.49 [95% CI: 0.80-2.78] for the 1st vs. 4th quartile of sRAGE).

CONCLUSIONS

sRAGE was strongly inversely associated with markers of inflammation at baseline, but not prospectively. sRAGE was not significantly associated with incident AF. This supports a role for sRAGE in attenuating current inflammation, but it remains unclear whether sRAGE plays a role in the development of AF.

Relation of low vitamin D to nonvalvular persistent atrial fibrillation in Chinese patients

BACKGROUND

Low vitamin D status has been associated with increased risk of cardiovascular disease. Atrial fibrillation (AF) is the most common cardiac arrhythmia. We evaluated the association between low vitamin D and AF.

METHODS

We analyzed data from 162 Chinese patients with nonvalvular persistent AF and no other cardiovascular disease whose serum 25-hydroxyvitamin D [25(OH)D] levels were measured in our hospital (AF group). Healthy subjects without AF who underwent health screening at our hospital served as controls (non-AF group, n = 160). 25(OH)D was measured by chemiluminescence assay.

RESULTS

The serum 25(OH)D level was significantly lower in the AF group than in the non-AF group (18.5 ± 10.3 vs 21.4 ± 10.7 ng/mL, P < 0.05). The high-sensitivity C-reactive protein (hsCRP) level was significantly higher in the AF group than in the non-AF group (0.35 ± 0.19 vs 0.2 ± 0.17 mg/dL, P < 0.01). The average left atrial diameter was significantly larger in the AF group than in the non-AF group (P < 0.01). The serum 25(OH)D level showed a negative correlation with left atrial diameter, hsCRP level, and pulmonary artery systolic pressure. Logistic regression analysis identified that 25(OH)D was related to AF. Patients whose vitamin D levels were in the lowest 25(OH)D category (<20 ng/mL) were more often in the AF group, with their incidence about twofold higher than those in the highest 25(OH)D category (>30 ng/mL).

CONCLUSIONS

Low vitamin D levels are associated with AF. It may be involved in its development.