[Cardiovascular syndrome X and endothelial dysfunction]

Coronary microvascular dysfunction

Coronary microvascular dysfunction (CMD) is a key mechanism underlying ischemic heart disease (IHD), yet its diagnosis and treatment remain challenging. This article presents a comprehensive overview of CMD research, covering its pathogenesis, diagnostic criteria, assessment techniques, risk factors, and therapeutic strategies. Additionally, it highlights the prospects for future CMD research. The article aims at advocating early and effective intervention for CMD and improving the prognosis of IHD.

Improved blood pressure and flow-mediated dilation via increased plasma adropin and NOx induced by high-intensity interval training in patients with type 2 diabetes

NEW FINDINGS

What is the central question of this study? Exercise training increases adropin and NOx plasma levels in middle-aged and older healthy people. We hypothesized that high-intensity interval training may improve blood pressure and flow-mediated dilation through the effects of adropin and NOx in patients of this age with type 2 diabetes. What is the main finding and its importance? High-intensity interval training may be more effective than moderate-intensity continuous training in improving endothelial function, blood pressure and flow-mediated dilation through its effects on adropin and NOx in patients with type 2 diabetes.

ABSTRACT

Adropin is a newly identified bioactive protein that is important in energy hemostasis and vascular endothelial function. Lower levels of adropin in patients with type 2 diabetes are related to coronary atherosclerosis, characterized by impaired flow-mediated dilation (FMD). The purpose of the present study was to investigate FMD, and plasma levels of adropin and nitrite/nitrate (NOx), in patients with type 2 diabetes at baseline and follow-up after 12 weeks of high-intensity interval training (HIIT) or moderate-intensity continuous training (MICT). Sixty-six persons with type 2 diabetes were divided into HIIT, MICT and control groups. The HIIT group intervention was 12 intervals (1.5 min) at 85% to 90% maximal heart rate (HR_max ) separated by 2 min at 55% to 60% HR_max in 3 session per week for 12 weeks. MICT training consisted of 42 min of cycling at 70% HR_max . Before and after the intervention, FMD was recorded with high-resolution Doppler ultrasound. Plasma levels of adropin and NOx were measured by enzyme-linked immunosorbent assay. After training FMD was significantly higher in the MICT and HIIT groups compared to the control group (P<0.05). Plasma levels of adropin and NOx were higher in both exercise groups, but the increase was greater in the HIIT group (P<0.01). Peak oxygen consumption was increased after exercise training in both groups compared to the control group (P<0.01). Percent FMD showed a positive correlation with plasma levels of adropin and NOx (both P<0.01), and a negative correlation with DBP (r = -0.530, P = 0.035) and SBP (r = -0.606, P = 0.013) in the HIIT group. The results indicate that HIIT improved FMD whilst increasing adropin, NOx and peak oxygen consumption. Increased plasma levels of adropin may contribute, in part, to blood pressure reduction by increasing nitric oxide production. This article is protected by copyright. All rights reserved.

The Mexican consensus on non-cardiac chest pain

INTRODUCTION

Non-cardiac chest pain is defined as a clinical syndrome characterized by retrosternal pain similar to that of angina pectoris, but of non-cardiac origin and produced by esophageal, musculoskeletal, pulmonary, or psychiatric diseases.

AIM

To present a consensus review based on evidence regarding the definition, epidemiology, pathophysiology, and diagnosis of non-cardiac chest pain, as well as the therapeutic options for those patients.

METHODS

Three general coordinators carried out a literature review of all articles published in English and Spanish on the theme and formulated 38 initial statements, dividing them into 3 main categories: (i)definitions, epidemiology, and pathophysiology; (ii)diagnosis, and (iii)treatment. The statements underwent 3rounds of voting, utilizing the Delphi system. The final statements were those that reached >75% agreement, and they were rated utilizing the GRADE system.

RESULTS AND CONCLUSIONS

The final consensus included 29 statements. All patients presenting with chest pain should initially be evaluated by a cardiologist. The most common cause of non-cardiac chest pain is gastroesophageal reflux disease. If there are no alarm symptoms, the initial approach should be a therapeutic trial with a proton pump inhibitor for 2-4weeks. If dysphagia or alarm symptoms are present, endoscopy is recommended. High-resolution manometry is the best method for ruling out spastic motor disorders and achalasia and pH monitoring aids in demonstrating abnormal esophageal acid exposure. Treatment should be directed at the pathophysiologic mechanism. It can include proton pump inhibitors, neuromodulators and/or smooth muscle relaxants, psychologic intervention and/or cognitive therapy, and occasionally surgery or endoscopic therapy.

Fenugreek (Trigonella Foenum-Graecum) Seed Flour and Diosgenin Preserve Endothelium-Dependent Arterial Relaxation in a Rat Model of Early-Stage Metabolic Syndrome

Fenugreek is a common herb possessing several bioactive components including diosgenin. Here, dietary fenugreek seed flour and diosgenin were evaluated on a model of endothelium-dependent vasorelaxation by abdominal aortas isolated from rats receiving high-fat, high-sugar diet (HFHSD). 60 male Wistar rats were randomized into six groups: (i) negative control getting conventional rat feed regimen; (ii) positive control receiving HFHSD; (iii) a test group fed 2 g/kg bw/day fenugreek seed flour (containing 10 mg/kg bw/day diosgenin) + HFHSD; (iv) three test groups fed 1, 10 and 50 mg/kg bw/day diosgenin + HFHSD. Alimentary treatments were carried out for six weeks. The abdominal aortas were isolated, and 2 mm wide rings were sectioned off and mounted at a resting tension of 10 mN in organ baths containing Krebs solution (36 °C) exposed to 95% O₂ and 5% CO₂. After 60-min incubation, a norepinephrine concentration-response (E/c) curve was generated to determine their half-maximal effective concentration (EC₅₀) value. After 60-min wash-out, a pre-contraction with norepinephrine EC₅₀ was made, followed by an acetylcholine E/c curve. Plasma glutathione levels, glutathione-handling enzyme activities and blood antioxidant capacities were also determined. HFHSD significantly decreased the dilatory response to acetylcholine and increased plasma glutathione levels and these effects were significantly reversed by fenugreek seed flour, 10 and 50 mg/kg bw/day diosgenin. Both fenugreek and diosgenin treatments prevent HFHSD-induced endothelial dysfunction and redox changes. As fenugreek treatment was more effective at lower acetylcholine concentrations than diosgenin treatments, components of fenugreek other than diosgenin may contribute to the beneficial effects of dietary fenugreek seed flour.

Deficiency of a new protein associated with cardiac syndrome X; called adropin

The pathophysiology of cardiac syndrome X (CSX) is still unclear, but most patients with CSX have endothelial dysfunction. It has been shown that adropin uniquely effects the regulation of endothelial function. The purpose of the study was to evaluate the role of adropin in CSX. Eighty-six consecutive cardiac syndrome X-diagnosed patients and 86 age-sex matched healthy subjects were enrolled into the study. Serum adropin levels, nitrite/nitrate levels were measured in each subject. The adropin levels were significantly lower in patients with CSX than healthy subjects (1.7 ± 0.8 ng/mL and 3.4 ± 1.8 ng/mL, respectively; P < 0.001). The BMI values of patients with CSX were significantly higher than control subjects (28.1 ± 2.4 kg/m(2) and 26.0 ± 3.7 kg/m(2) , respectively; P < 0.001). Plasma nitrite/nitrate levels were lower in patients with CSX than control subjects (15.9 ± 1.6 μmol/L vs. 25.4 ± 2.8 μmol/L, respectively; P < 0.001), and they have a significantly positive correlation with plasma adropin levels (r = 0.463, P < 0.001). In the multiple linear regression analysis, nitrite/nitrate levels, BMI, and adropin were found to be independent risk factors for CSX. A ROC curve is used to identify the ability of adropin levels to predict the cardiac syndrome X. The area under the ROC curve was 0.854 for adropin levels (P = 0.0001). The sensitivity and specificity values of adropin levels were 90.7 and 70.9%, respectively (cut-off value 2.73). In conclusion, lower serum adropin levels were associated with CSX. Adropin is an independent risk factor for CSX.

Role of inflammation and endothelial dysfunction in the pathogenesis of cardiac syndrome X

Chest pain with normal coronary arteriograms represents a major diagnostic and therapeutic challenge to contemporary cardiology. Cardiac syndrome X (CSX), defined as typical angina-like chest pain, a positive response to exercise stress testing and normal coronary arteriograms, encompasses patients with a variety of pathogenic mechanisms. Cardiac ischemia has been documented in approximately 25% of CSX patients and is associated with endothelial dysfunction and microvascular vasodilator abnormalities. Increased endothelin-1, a powerful vasoconstrictor, has been suggested to play a pathogenic role. There is a high prevalence of postmenopausal women with CSX and thus estrogen deficiency has also been proposed to represent a possible pathogenic mechanism. Inflammatory mechanisms and endothelial dysfunction at the coronary microvascular level appear to be important in the pathogenesis of CSX. Treatment with agents that have protective effects on the vasculature and also anti-inflammatory properties, such as statins and angiotensin-converting enzyme inhibitors have been effective in improving both symptoms and electrocardiographic signs of myocardial ischemia in patients with CSX. This review discusses the roles for endothelial dysfunction and inflammation in the pathogenesis of CSX, as well as the potential therapeutic implications of these mechanisms.

Altered transcriptional activity of gene encoding GAPDH in peripheral blood mononuclear cells from patients with cardiac syndrome X - an important part in pathology of microvascular angina?

INTRODUCTION

Cardiac syndrome X (CSX) is characterized by anginal pain with ECG suggestive of ischaemia and normal coronary arteries at angiography. Pathology of CSX involves microvascular dysfunction and is possibly linked with metabolic syndrome. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is an enzyme involved in glycolysis. The GAPDH gene is a "housekeeping" gene and is used for normalization in quantitative gene expression assays. The aim of the study was to evaluate GAPDH gene expression in CSX.

MATERIAL AND METHODS

The study was performed in 35 CSX patients and 10 control subjects. mRNA was extracted from peripheral blood mononuclears and the mRNA was assessed by QRT-PCR.

RESULTS

GAPDH gene expression was enhanced in CSX patients vs. controls (93022 ±23837 copies/μg vs. 1067 ±240 copies/μg respectively; p < 0.001). Moreover, transcriptional activity of the GAPDH gene was heterogeneous within the CSX group.

CONCLUSIONS

GAPDH gene expression is markedly enhanced in CSX, which reflects carbohydrate metabolism disturbances and makes the GAPDH gene unsuitable as an endogenous control in patients with CSX.

Gene expression of kinin receptors B1 and B2 in PBMC from patients with cardiac syndrome X

INTRODUCTION

Cardiac syndrome X (CSX) is defined by typical chest pain, ST segment depression on ECG and normal coronary angiography. Pathology of CSX may involve microvascular dysfunction related to inflammation and abnormal pain sensitivity. Kinins are labile peptides participating in vasodilation, inflammation and pain. Their effects are mediated by two receptors: B1 and B2. The aim of the study was to assess gene expression of kinin receptors in peripheral blood mononuclear cells (PBMC) from patients with CSX.

METHODS

The study was carried out in 34 patients with cardiac syndrome X, 13 with unstable angina and ten healthy subjects. Total mRNA was extracted from PBMC and the number of mRNA copies was assessed by quantitive reverse transcriptase polymerase chain reaction.

RESULTS AND CONCLUSION

The study showed 7-fold higher transcriptional activity of B1R in CSX vs. control and 3.5 higher vs. UA. B2R expression was 2.5-fold higher in CSX group vs. control and UA, while in the letter two groups it was similar. Such disturbance in kinin signaling may participate in local vasoconstriction and may reflect disturbances in kinin signaling leading to nociceptive disturbances in these patients.

Transcriptional activity of genes encoding interferon gamma (IFNgamma) and its receptor assessed in peripheral blood mononuclear cells in patients with cardiac syndrome X

BACKGROUND

Cardiac syndrome X is typically characterized by effort induced anginal pain with ST segment depression suggestive of myocardial ischemia and normal coronary arteries at angiography. The possible mechanism that may participate in the pathology of CSX is a microvascular dysfunction related to inflammatory process affecting endothelium. Interferon gamma (IFN-gamma) is an important cytokine in inflammatory reaction. It acts through its specific receptor composed of 2 subunits IFN-gamma R1 (ligand binding) and R2 (signal transduction). The expression and proportion of these subunits influences IFN-gamma activity. The aim of the study was to assess the gene expression of IFN-gamma and its receptors in peripheral blood mononuclear cells (PBMC) from patients with syndrome X.

METHODS

The study was carried out in 36 patients aged 44-77 (average 57 years old) with cardiac syndrome X and 23 sex- and age-matched healthy subjects (control group). To evaluate gene expression of IFNgamma and its receptor total mRNA was extracted from peripheral blood mononuclear cells (PBMC) and the number of mRNA copies were assessed by quantitive reverse transcriptase polymerase chain reaction (QRT-PCR).

RESULTS

We have not observed statistically significant differences in INFgamma gene expression between studied group and control. Genes encoding IFNgamma receptor subunits showed higher expression in PBMCs from patients with cardiac syndrome X vs control subjects (IFNgammaR1, 97,244 +/- 26,956 c/microg vs 12,120 +/- 2,940 c/microg, p < 0.005, respectively and IFNgammaR2, 129,153 +/- 36,883 c/microg vs 16,445 +/- 2,923 c/microg, p < 0.005, respectively).

CONCLUSION

Variation in transcriptional activity of genes encoding INF-gamma receptor subunits may affect function of microvasculature and thereby participate in the pathology of cardiac syndrome X.

Brachial artery flow-mediated dilation and myocardial perfusion in patients with cardiac syndrome X

We assessed the relation between systemic endothelial dysfunction abnormalities (brachial artery flow-mediated dilation) and myocardial perfusion abnormalities (single-photon emission computed tomography) in 41 patients who had cardiac syndrome X. Eighteen patients had normal perfusion scans and 18 had transient perfusion defects. Reverse redistribution was found in 5 patients. Patients who had myocardial perfusion defects had significantly lower flow-mediated dilation values (1.8%) than patients who had normal single-photon emission computed tomograms (3.9%, p = 0.012). Preserved systemic endothelial function appears to rule out the occurrence of transient single-photon emission computed tomographic defects in patients who have cardiac syndrome X.

Decreased serum osteoprotegerin levels in patients with cardiac syndrome X

Receptor activator of nuclear factor KB (RANK) and osteoprotegerin (OPG) represent the ligand and decoy receptor, respectively, of a pleiotropic cytokine system that regulates bone metabolism and vascular biology. Several studies supported systemic microvascular abnormalities in patients with cardiac syndrome X (CSX). This study investigates serum OPG levels in healthy obese subjects and healthy lean controls affected by cardiac syndrome X.

METHODS

We compared the OPG levels in 8 patients with cardiac syndrome X [2 males, 6 females; age: 46+/-6 yr; body mass index (BMI): 30+/-5 kg/m2] with 24 obese subjects (8 males, 16 females; age: 38+/-5 yr; BMI: 35+/-5 kg/m2) and 15 healthy lean controls (6 males, 9 females; age: 36+/-5 yr; BMI: 23+/-2 kg/m2; BMI<25kg/m2).

RESULTS

Serum OPG levels in patients with cardiac syndrome X were lower than those in obese subjects and lean controls (11.45+/-8.36 pg/ml, 14.78+/-8.22 pg/ml, 19.24+/-6.96 pg/ml, respectively, cardiac syndrome X vs lean controls, p=0.039).

CONCLUSIONS

Serum OPG levels are lower in patients with CSX. Further studies on the mechanisms of OPG in microangiopathy may help to evaluate the OPG system role as a marker for disease activity, prognosis and response to therapy in cardiovascular diseases.