Georgios Bouras

Colchicine for Prevention of Early Atrial Fibrillation Recurrence After Pulmonary Vein Isolation : A Randomized Controlled Study

OBJECTIVES The purpose of the present study was to test the potential of colchicine, an agent with potent anti-inflammatory action, to reduce atrial fibrillation (AF) recurrence after pulmonary vein isolation in patients with paroxysmal AF. BACKGROUND Proinflammatory processes induced by AF ablation therapy have been implicated in postablation arrhythmia recurrence. METHODS Patients with paroxysmal AF who received radiofrequency ablation treatment were randomized to a 3-month course of colchicine 0.5 mg twice daily or placebo. C-reactive protein (CRP) and interleukin (IL)-6 levels were measured on day 1 and on day 4 of treatment. RESULTS In the 3-month follow-up, recurrence of AF was observed in 27 (33.5%) of 80 patients of the placebo group versus 13 (16%) of 81 patients who received colchicine (odds ratio: 0.38, 95% confidence interval: 0.18 to 0.80). Gastrointestinal side-effects were the most common symptom among patients receiving active treatment. Diarrhea was reported in 7 patients in the colchicine group (8.6%) versus 1 in the placebo group (1.3%, p = 0.03). Colchicine led to higher reductions in CRP and IL-6 levels: the median difference of CRP and IL-6 levels between days 4 and 1 was -0.46 mg/l (interquartile range: -0.78 to 0.08 mg/l) and -0.10 mg/l (-0.30 to 0.10 pg/ml), respectively, in the placebo group versus -1.18 mg/l (-2.35 to -0.46 mg/l) and -0.50 pg/ml (-1.15 to -0.10 pg/ml) in the colchicine group (p < 0.01 for both comparisons). CONCLUSIONS Colchicine is an effective and safe treatment for prevention of early AF recurrences after pulmonary vein isolation in the absence of antiarrhythmic drug treatment. This effect seems to be associated strongly with a significant decrease in inflammatory mediators, including IL-6 and CRP.

Myeloperoxidase: expressing inflammation and oxidative stress in cardiovascular disease.

Myeloperoxidase (MPO), a heme protein released by leukocytes, is one of the most widely studied during the last decades molecule that plays a crucial role in inflammation and oxidative stress in the cellular level. It has become increasingly recognized that MPO performs a very important role as part of the innate immune system through the formation of microbicidal reactive oxidants, whilst it affects the arterial endothelium with a number of mechanisms that include modification of net cellular cholesterol flux and impairment of Nitric Oxide (NO)-induced vascular relaxation. In that way, MPO is implicated into both the formation and propagation of atheromatosis and there is substantial evidence that it also promotes ischemia through destabilization of the vulnerable plaque. Numerous studies have added information on the notion that MPO and its oxidant products are part of the inflammatory cascade initiated by endothelial injury and they are significantly overproduced at the site of arterial inflammation. Subsequent studies achieved quantification of this observation showing significant elevations of the systemic levels of MPO in a wide spectrum of cardiovascular disease scenarios with acute coronary syndromes and heart failure being the most studied. This review highlights key-aspects of MPOs pathophysiological properties and summarizes the role of MPO as a diagnostic and prognostic tool for a number of cardiovascular pathologies.

Cystatin C: An Emerging Biomarker in Cardiovascular Disease

Cystatin C (cys-C) is a small protein molecule (120 amino acid peptide chain, approximately 13kDa) produced by virtually all nucleated cells in the human body. It belongs to the family of papain-like cysteine proteases and its main biological role is the extracellular inhibition of cathepsins. Its near constant production rate, the fact that it is freely filtered from the glomerular membrane and then completely reabsorbed without being secreted from the proximal tubular cells, made it an almost perfect candidate for estimating renal function. The strong correlation between chronic kidney disease (CKD) and cardiovascular disease (CVD) along with the growing understanding of the role of cysteinyl cathepsins in the pathophysiology of CVD inspired researchers to explore the potential association of cys-C with CVD. Throughout the spectrum of CVD (peripheral arterial disease, stroke, abdominal aortic aneurysm, heart failure, coronary artery disease) adverse outcomes and risk stratification have been associated with high plasma levels of cys-C. The exact mechanisms behind the observed correlations have not been comprehensively clarified. Plausible links between high cys-C levels and poor cardiovascular outcome could be impaired renal function, atherogenesis and inflammatory mediators, remodeling of myocardial tissue and others (genetic factors, aging and social habits). The scope of the present article is to systematically review the current knowledge about cys-C biochemistry, metabolism, methods of detection and quantification and pathophysiological associations with different aspects of CVD.

NTproBNP: An Important Biomarker in Cardiac Diseases

Natriuretic neuropeptides (ANP, BNP, CNP) are produced primarily in the cardiac atria under normal conditions. The main stimulus for ANP and BNP peptide synthesis and secretion is cardiac wall stress. Cardiac ventricular myocytes constitute the major source of BNP-related peptides. Ventricular NT-proBNP production is upregulated in cardiac failure and locally in the area surrounding a myocardial infarct. NT-proBNP is cleared passively by organs with high rate of blood flow (muscle, liver, kidney). It has a longer half life than BNP and higher plasma concentration. BNP and NTproBNP tend to be higher in women and lower in obese individuals. They are also higher in elderly, in left ventricular tachycardia, right ventricular overload, myocardial ischemia, hypoxaemia, renal dysfunction, liver cirrhosis, sepsis and infection. NT-proBNP is useful both in the diagnosis and prognosis of heart failure and is considered to be a gold standard biomarker in heart failure similar to BNP. A cut-off point 300 pg/ml has 99% sensitivity, 60%specificity and NPV 98%for exclusion of acute heart failure. NT proBNP has also a strong prognostic value of death in acute and chronic heart failure and also predicts short and long term mortality in patient with suspected or confirmed unstable CVD. Natriuretic peptides are also prognostic markers for the RV (Right Ventricular) Dysfunction. Their release is due to myocardial stretch from right ventricular pressure overload.Finally, there are data supporting that NT-proBNP might be useful to put a time frame on atrial fibrillation of unknown onset.

Red blood cell and platelet microparticles in myocardial infarction patients treated with primary angioplasty.

BACKGROUND Red blood cell and platelet microparticles (RBCm and PLTm, respectively) have drawn research attention as to their potential prothrombotic and vasoconstrictive effects in experimental settings. However, the relevance of circulating microparticles in clinical settings is largely undetermined. METHODS Circulating microparticles were quantified with a flow cytometric method in blood samples from consecutive STEMI patients after primary PCI. A matched cohort of healthy volunteers was used to derive reference values for comparison. STEMI patients were followed for 6 months for a composite clinical endpoint. RESULTS Fifty-one STEMI patients (age 59.8 ± 8.8 years) and 50 controls (age 56.2 ± 9.2 years; p=0.155) were enrolled. RBCm concentration was 18,198 ± 6062/μl in the reference cohort versus 33,740 ± 21,169/μl in STEMI patients (p<0.001). RBCm count was not correlated to total RBCs (standardized beta 0.018; p=0.861). PLTm did not differ between groups (17,529 ± 16,292/μl in STEMI patients versus 14,372 ± 6211/μl in controls; p=0.203). RBCm c-statistic was 0.832 (95% confidence interval 0.720 to 0.944), while PLTm prognostic value was not statistically significant (c-statistic 0.614, 95% confidence interval 0.444 to 0.784). In the multivariate analysis, RBCm concentration was independently associated with the occurrence of the clinical endpoint, after adjustment for age, ejection fraction, serum creatinine and presence of diabetes (adjusted p=0.034). CONCLUSIONS The present study demonstrates for the first time that erythrocyte microparticles are elevated in patients with STEMI treated with primary PCI, with levels approximately double those measured in a reference population of healthy volunteers, and their concentrations appear to be positively associated with adverse clinical events.

The role of endothelin system in cardiovascular disease and the potential therapeutic perspectives of its inhibition.

Since its identification in 1988 and the recognition of its primary role as a potent vasoconstrictor, endothelin has been extensively studied and is now considered as a ubiquitous protein, involved in important aspects of human homeostasis as well as in several pathophysiological pathways, mostly associated with cardiovascular disease. From an evolutionary point of view, endothelin consists a primitive molecule with the rare characteristic of being exactly the same in all mammals, thus permitting scientists to perform experiments in animals and doing predictions for humans. The understanding of its contribution to the genesis, evolution and maintenance of disease through activation of special receptor subtypes has led to the development of both selective and unselective receptor antagonists. Despite the disappointing results of these antagonists in the field of heart failure, almost from the initial animal trials of bosentan, a dual endothelin receptor antagonist, in pulmonary arterial hypertension, it has been demonstrated that the drug leads at least to hemodynamic and clinical improvement of the patients, thus receiving official approval for the management of this rare but eventually lethal disease. Resistant hypertension is another area where endothelin receptor blockers might potentially play a role, while the pathophysiological role of endothelin in atherosclerotic coronary artery disease is well-established and the relative research goes on. The main goal of this review is to describe the endothelin system and mostly to enlighten its role in pathophysiologic pathways, as well to state the relative research in the various fields of cardiovascular disease and also highlight its prognostic significance wherever there exists one.

Inflammation and chronic heart failure: from biomarkers to novel anti-inflammatory therapeutic strategies.

Heart failure (HF) is a complex heterogeneous syndrome with immune, metabolic and neurohumoral mechanisms interacting and leading to gradual heart contractility impairment. From the first study-to correlate inflammation with HF, inflammation biomarkers have been the subject of intense inquiry in patients with various forms of HF. Chronic HF (CHF) is strongly associated with inflammation in terms of pathogenesis, progression, severity and prognosis. Inflammatory mediators participate in CHF pathophysiology in various ways like exerting direct impact on cardiac myocytes, fibroblasts and β-adrenergic receptors leading to hypertrophy, fibrosis and impaired cardiac contractility, respectively, or inducing apoptosis by stimulation of the proper genes. The anti-inflammatory effects of classical heart failure therapeutic strategies such as ACEI and b-blockers are rather conflicting. Whether novel immunomodulating and anti-inflammatory therapeutic approaches should be added to existing therapies in order to ensure additional benefit to HF patients is under investigation. In this review, we summarize the pathophysiological link between inflammatory processes and CHF, focusing on the role of novel and traditional inflammatory biomarkers and highlighting novel anti-inflammatory therapeutic strategies.

Inflammation Markers in Essential Hypertension

Essential hypertension is a common health disorder with uncertain etiology and unclear pathophysiology. There is evidence that various systems interact in uncertain ways and mechanisms to cause hypertension. It is also well known that inflammation is a key feature in the initiation, progression and clinical implication of several cardiovascular diseases. Recently, it has become evident that the immune system and inflammatory response are also essential in the pathogenesis of hypertension. Many inflammation markers such as CRP, cytokines, and adhesion molecules have been found elevated in hypertensive patients supporting the role of inflammation in the pathogenesis of hypertension. Also, in normotensive individuals, these markers have been associated with the risk of developing hypertension, whereas in hypertensive patients they have been associated with target organ damage as well as with the risk for future cardiovascular events. Thus, understanding the role of inflammation in hypertension provides new insights for novel therapeutic approaches, targeting inflammation for the treatment of hypertension and its complications.

Interatrial conduction time and incident atrial fibrillation: a prospective cohort study.

BACKGROUND Atrial electrical conduction properties have been implicated in atrial fibrillation (AF) pathogenesis. OBJECTIVE The purpose of this study was to prospectively assess the potential association of interatrial conduction time (IACT) with incident AF. METHODS The study included persons referred for invasive electrophysiologic study (EPS), aged ≥50 years, without AF history or valvular disease. IACT was defined as the interval between the high right atrium electrogram and the distal coronary sinus atrial electrogram. RESULTS Six hundred twelve subjects were included (median follow-up 43 months, interquartile range 40-47). AF incidence was 21.7 cases per 1000 person-years. IACT was a significant predictor of AF with a c-statistic of 0.770 (95% confidence interval 0.702-0.838). In time-dependent analysis, IACT was a significant stratifier of AF risk (log-rank 28.0, P <.001). The corresponding incidences of AF in each tertile of IACT were 3, 17, and 46 per 1000 person-years, respectively (all differences between tertiles were significant). IACT remained significant in multivariable Cox regression analysis, after adjustment for age, sex, hypertension, and left atrial diameter, with each millisecond of prolonged IACT corresponding to 7% (95% confidence interval 2%-12%) higher adjusted risk of incident AF. CONCLUSION IACT is independently associated with incident AF. The invasive nature of the measurement is a limitation for its use as a clinical risk stratifier (although it could be used in patients referred for EPS), but these results are of interest in themselves because they suggest a strong pathophysiologic connection between atrial conduction times and substrate alterations ultimately leading to AF.

Copeptin as a Biomarker in Cardiac Disease

The introduction of biochemical biomarkers in the evaluation of patients with cardiovascular disease has led to practice-changing advancements in the way these patients are diagnosed and managed. Measurements of cardiac troponins or brain-type natriuretic peptide (BNP) and its precursor, N-terminal brain-type natriuretic peptide (NT-proBNP), have become indispensable in the evaluation of patients with acute coronary syndromes and heart failure, respectively, constituting an integral part of the diagnostic algorithm and risk stratification of these conditions. Copeptin, a glycopeptide, part of the prehormone molecule of the antidiuretic hormone - or arginine-vasopressin - has shown considerable promise in this field. There is evidence that copeptin might be useful as a diagnostic or prognostic biomarker and risk-stratifier in a range of cardiovascular disease conditions. The main clinical scenarios where copeptin has been studied as a biomarker are: early rule-out of myocardial infarction in patients with acute chest pain, diagnosis of heart failure in patients with acute dyspnea and determining the prognosis of destabilized or chronic stable heart failure. The present review is aimed at providing concise information about the molecular structure and biosynthesis of copeptin, the available medical chemistry methods of quantification, and the potential clinical uses of this molecule in patients with heart disease.