Ekaterina Sergeevna Sitkova

Multiple pathogenetic factors related to activation of blood clotting system and platelet aggregation may significantly contribute to occurrence of thromboembolic complications in cardiac arrhythmias. The relevant studies are closely focused on associations between congenital risk factors of thrombosis, and biomarkers that may be related to pathogenesis of thrombotic events in atrial fibrillation. Our objective was to study the relationships between markers of inflammation and platelet activation with polymorphic variants of genes of the hemostasis system and platelet receptors among patients with non-valvular atrial fibrillation receiving anticoagulant therapy with a history of thrombotic complications, and patients with atrial fibrillation without previous thrombotic complications. The study included 60 patients diagnosed with atrial fibrillation, 21 patients developed thrombotic complications. All patients have provided a written informed consent for inclusion in the study. A diagnostic panel of biomarkers, polymorphic variants of genes and platelet aggregation tests was conducted using the facilities at the Center for Collective Use “Medical Genomics” (Tomsk National Research Medical Center, Russian Academy of Sciences, Tomsk, Russian Federation). Comparative frequency of polymorphic variants of plasminogen activator inhibitor PAI-1 , platelet collagen receptor ITGA2 , nitric oxide synthase NOS3 , and β-2 adrenergic receptor ADRB2 genes did not show any statistically significant differences between patients with or without thrombotic complications. Meanwhile, we have found a decrease in the levels of α-acid glycoprotein, fetuin A, L-selectin, thrombomodulin and increased in CD40L and platelet factor 4 levels in the group of patients with thrombotic complications, compared with patients without thrombosis. A statistically significant difference was noted in the subgroups with a high-risk genotype of thrombosis. The higher-risk genotypes of PAI-1 and ITGA2 genes in the group with thrombotic complications was associated with increased platelet aggregation activity and increased platelet factor 4 contents. A search for associations between markers of inflammation and platelet activation, and polymorphic variants of hemostasis system genes and platelet receptors showed a link between the high-risk genotypes, increased CD40L, platelet factor 4, and aggregation activity among patients with thrombotic complications.

Despite the rapid development of interventional treatment modalities and the introduction of novel antiarrhythmic drugs, amiodarone continues to occupy a unique niche in long-term relapse prevention therapy for atrial fibrillation. This is particularly relevant for patients with organic myocardial disease, chronic heart failure with reduced ejection fraction, and in regions with limited access to catheter ablation or costly alternative medications. However, the complex, multifactorial pharmacokinetics of amiodarone – high lipophilicity, enormous volume of distribution, the presence of the pharmacologically active metabolite desethylamiodarone, and an exceptionally long elimination half-life – pose significant challenges for clinicians. A narrow therapeutic window and a high risk of dose-dependent adverse effects justify the potential value of therapeutic drug monitoring (TDM). The lecture based on a critical appraisal of available evidence and real-world clinical data reviews current perspectives on the clinical significance of measuring amiodarone and desethylamiodarone concentrations. Pharmacokinetic features that determine patient management strategies are discussed in detail, along with the controversies surrounding existing clinical guidelines and the methodological limitations of published studies. Particular attention is devoted to identifying clinical scenarios in which TDM may be most informative and to outlining directions for future randomized controlled trials.

Introduction . The problem of neurogenic bradycardia among young adults is socially significant, as it is associated with the need for surgical treatment, the only option for which has long been pacemaker implantation. Cardioneuroablation is a new method that has demonstrated its efficacy and safety in the treatment of neurogenic bradycardia. Brief description . This article presents a case of successful treatment of neurogenic binodal disease in a young patient after pacemaker extraction due to an infectious complication. Cardioneuroablation improved sinoatrial and atrioventricular node automaticity and eliminated clinical symptoms associated with bradycardia. Follow-up demonstrated a sustained effect lasting up to 3 months, with improved quality of life and no need for pacemaker reimplantation. Discussion . The potential to eliminate vagotonic effects on the cardiac conduction system through destruction of the parasympathetic atrial ganglionic plexuses underlies the cardioneuroablation method. According to several studies, the achieved improvement in the functional state of the sinoatrial and atrioventricular nodes is sustainable during long-term follow-up. The alternative of eliminating bradycardia without pacemaker implantation allows for the avoidance of unnecessary infectious complications while improving the patient’s quality of life and clinical status. Conclusion . This case clearly demonstrates the importance of diagnosing the autonomic causes of cardiac conduction system dysfunction in young patients and the potential for their elimination using cardioneuroablation, which makes it possible to avoid pacemaker implantation and the risk of related complications.

Aim. To assess the relationship between structural and functional parameters of the heart and the presence and prevalence of low-amplitude activity (LAA) zones according to high-density voltage mapping of the left atrium (LA) in patients with atrial fibrillation (AF). Methods. The study included 57 patients (23 women and 34 men) 55.4±9.8 years with paroxysmal (n=40, 70%) and persistent AF (n=17, 30%). Transthoracic echocardiography, assessment of deformation of both atria - 2D Strain STE were performed in all patients. High-density voltage mapping of the LA was performed intraoperatively before the catheter ablation procedure. Results. LAA zones were registered in 33% of patients. Persistent form of AF, LA stiffness index, reservoir and contractile functions of the LA, E/A and E/e’ ratios became the strongest predictors of identifying LAA zones in the LA. A prognostic model was constructed using the LA stiffness index and E/A ratio, which determines a high probability of identifying LAA zones in the LA with a sensitivity and specificity of 74 and 74%, respectively. Conclusion. Preoperative assessment of the stiffness index, reservoir and contractile function of the LA, E/A and E/e’ ratios has predictive value in assessing the prevalence of fibrosis using high-density voltage mapping of the LA. Studying of noninvasive ultrasound parameters in combination with known predictors of effectiveness will allow us to create algorithms for selecting patient selection for catheter ablation and avoid predictably ineffective interventions.

Introduction . Achieving therapeutic concentrations of direct oral anticoagulants (DOAC) and, accordingly, personalization of anticoagulant therapy in certain groups of patients are becoming increasingly important. To optimize drug monitoring in routine clinical practice, it is necessary to develop and test sensitive and selective methods that can quantitatively determine the content of DOAC in the blood, including rivaroxaban. Aim: To modify the method for determining the concentration of rivaroxaban in the blood using high-performance liquid chromatography (HPLC), as well as testing the selected conditions for determining the concentration of the drug in the whole venous blood of patients. Material and Methods . For the first stage of the work, the samples for the study were blood samples (n = 20) from healthy volunteers (n = 5) not taking medications. Blood was collected from a peripheral vein using a vacuum system in a volume of 6 ml. Blood collection tubes with four different fillings were used. Before preparation, the samples were divided into 6 parts and each was supplemented with a solution of rivaroxaban of different concentrations, prepared from the pure substance Rivaroxaban (India). Next, liquid extraction of rivaroxaban with acetonitrile from a sample of whole venous blood was carried out with parallel elimination of the interfering effect of proteins by precipitation with nickel chloride. The separation of the sample components was performed by reversed-phase highperformance liquid chromatography on a liquid chromatograph (1260 Infinity II LC). The analytical signal on a diode-array detector (1260 DAD WR, Agilent Technologies) was recorded at two wavelengths of 254 nm and 280 nm. For the second stage of the work, the samples for the study were whole venous blood samples from patients taking rivaroxaban (n = 54). Blood is collected in the morning, on an empty stomach, 12 hours after taking the last dose of the drug. Results. The authors investigated and established the factors influencing the decrease in the detection limit of rivaroxaban (Bayer, Germany) in the blood when determining it by HPLC using an Agilent 1260 liquid chromatograph with a diode array detector (Agilent Technologies, Germany). To assess the degree of rivaroxaban extraction and select the working wavelength, calibration dependences of the anticoagulant in the initial acetonitrile solutions and graphs of changes in the peak areas of rivaroxaban from its content in the blood were constructed: at a wavelength of 254 nm (r ² = 0.98) and 280 nm (r ² = 0.99). The dependence function at a wavelength of 254 nm has a larger slope, which makes it possible to reduce the detection limit of the substance being determined. The silicon dioxide content in the tube does not significantly affect the analytical signal of rivaroxaban (minimum detection limits 0.25 µg/ml, minimum determination limits 0.77 µg/ ml), and does not introduce additional error into the accuracy of the method. The median concentration of rivaroxaban was 0.32 µg/ ml (0.26; 0.49) 12 hours after taking the drug. Conclusion. The use of a modified HPLC method with a wavelength of 254 nm selected for detecting the analytical signal makes it possible to reduce the detection limit of the substance being determined and increase the range of concentrations being determined. And the use of tubes with silicon dioxide can be recommended for decreasing the influence of the matrix effect on the quantitative determination of rivaroxaban in blood and increasing the accuracy of the method.

Background. Amiodarone is widely used as an antiarrhythmic drug, but its effectiveness is not entirely predictable, and its side effects are not completely controllable. To determine the effective concentration of amiodarone in the blood, a method for quantitative analysis of the drug in the presence of a biological matrix is needed. Objective. To develop a procedure for quantitative determination of amiodarone (AMI) and desethylamiodarone (DEA) in blood plasma by high-performance liquid chromatography (HPLC). Materials and Methods. The procedure was developed using an Agilent 1260 Infinity chromatograph with diode array detector (Agilent, USA) on a Tsunami C18 Pharm column (250×4.6 mm, 5 μm) with proprietary stationary phase. Agilent Zorbax SB C8 precolumn (9.4×15 mm, 7 μm) was used to protect the column from mechanical contaminants. Validation was performed according to OFS.1.1.0012.15 “Validation of Analytical Methods” for the following parameters: selectivity, matrix effect, linearity, accuracy, precision, stability and limits of detection and quantification. Results. The QuEChERS sample preparation was modified to achieve optimal conditions for the extraction of AMI and DEA from the biological matrix. Mobile phase A was phosphate buffer (pH 3, 7.5 mM), mobile phase B was 100% acetonitrile. The separation was performed in gradient mode. Up to 7.00 minutes – the B phase content was 55%, from 7.00 to 7.15 minutes – an increase in B phase content to 85% in order to elute the more hydrophobic components, from 7.15 to 15.00 minutes – the B phase content did not change, followed by a return to the original 50% at 15.15 min. The total analysis time was 18 minutes. Column thermostat temperature was set to 30 °C, flow rate – 1.2 mL/min; injection volume – 80 µL; selective wavelength was 241 nm. The value of retention factor for AMI was 2.25; for DEA – 1.44. Conclusion. The authors have developed and validated the new HPLC procedure for quantitative identification of AMI and DEA in human blood plasma.

Aim. To analyze the significance of contrast-enhanced cardiac magnetic resonance imaging (MRI) and endomyocardial biopsy (EMB) in the diagnosis of myocarditis in patients with atrial fibrillation (AF) of unknown origin.Material and methods. The study included 57 patients with AF of unknown origin aged 45,5 [38,8;53,3] years (men, 77,2%). Paroxysmal AF was observed in 56,1% of patients, while persistent AF — in 22,8%, and long-standing persistent AF — in 21,1%. Thirty-five patients underwent contrast-enhanced cardiac MRI and Lake-Louise criteria assessment. Simultaneously with AF ablation, all patients underwent EMB from the interventricular septum, outflow tract, and right ventricular apex with histological diagnosis of myocarditis based on the Dallas criteria modified by the World Heart Federation.Results. According to contrast-enhanced cardiac MRI, delayed contrast accumulation was diagnosed in 91,4%. In 17,1% of cases, signs of edema were detected on T2-weighted images, while the average left ventricular (LV) edema level was 1,6±0,3 (reference Conclusion. Myocarditis was diagnosed in 34,3% of patients according to MRI and in 49,1% according to EMB. Edema according to MRI data was the only sign that had predictive value for the severity of inflammatory cell infiltration in myocardial fragments. Histological analysis in combination with MRI increased the accuracy of myocarditis diagnosis in patients with AF of unknown origin from 34,3 to 62,9%.

Recent studies have demonstrated increased interest in development of new laboratory methods for assessing the risk of thromboembolic complications in atrial fibrillation. Soluble thrombomodulin (sTM) is one of the biomarkers that exhibit important anti-inflammatory, anticoagulant and antifibrinolytic properties and are involved in maintenance of vascular homeostasis. Our objective was to study the contents of soluble thrombomodulin (sTM) in blood serum of the patients with non-valvular atrial fibrillation receiving anticoagulant therapy with a history of thrombotic complications versus a group of patients with atrial fibrillation without thrombotic complications. The study included 60 patients over 18 years of age diagnosed with atrial fibrillation, which was verified according to clinical recommendations, who received anticoagulant therapy. Of this group, 21 patients developed thrombotic complications during adequate anticoagulant therapy. 22 healthy volunteers were also included into the study. Evaluation of soluble thrombomodulin in blood serum was carried out by ELISA technique using the facilities at the Center for Collective Use “Medical Genomics” of the Tomsk National Research Medical Center. All the examined patients were divided into 2 groups: a group of patients with atrial fibrillation without thrombotic complications (TC), and a group of patients with atrial fibrillation who developed TC. The sTM content in blood serum of patients with thrombotic complications was reduced, when compared with results obtained in patients without thrombotic complications, and among healthy volunteers. Analysis of the sTM level in men and women in groups of patients and in healthy volunteers showed that the values of this serum biomarker were lower in female patients with atrial fibrillation and TC, when compared with women from the group of patients without TC and with healthy females. Moreover, the content of soluble thrombomodulin prove to be reduced in men with thrombosis compared to healthy males. A comparative analysis of sTM levels in women and men in all groups did not reveal statistically significant differences. In the studied group of patients with non-valvular atrial fibrillation receiving anticoagulant therapy, a decrease in sTM levels was noted in the subgroup of patients with TC.

Aim. Search for predictors of early recurrence of atrial tachyarrhythmias after radiofrequency ablation (RFA) of atrial fibrillation (AF).Methods. The study included 57 subjects with persistent (n = 17; 30%) and paroxysmal (n = 40; 70%) forms of AF, admitted for the RFA. All patients underwent transthoracic echocardiography, assessment of deformation of both atria using 2D Strain, computed tomography (CT) with 3D reconstruction of the left atrium (LA). Intraoperatively, high-density voltage mapping of LA was performed before RF pulmonary vein isolation. All patients underwent follow-up after 3 months.Results. Recurrence of atrial tachyarrhythmia after 3 months was recorded in 17.5% of patients. High prevalence of low-amplitude activity zones in the LA and persistent AF were the strongest predictors. The LA reservoir function below 21.7%, the conduction function below 15.7%, the LA stiffness index above 0.314 relative units, the LA volume with the appendage above 121.7 ml, and the LA vertical size according to CT data above 65.5 mm statistically significantly predicted early recurrences of atrial tachyarrhythmias with high sensitivity and specificity.Conclusion. The decreased LA deformation in the reservoir and conductor phase, increased LA stiffness index, the prevalence of low-amplitude activity zones, vertical size and volume of the LA with an auricle according to CT data and persistent AF are significant predictors of early relapses after interventional treatment of AF.

Aim. To assess the incidence of chronic myocarditis in patients with atrial fibrillation.Material and methods. The study included 145 patients. The majority of patients were male — 118 (81.4%). The median age was 45 (38; 50) years. Most had paroxysmal AF — 60 (41.4%), slightly fewer had persistent AF — 55 (37.9%), 30 (20.7%) patients had long-term persistent AF. All patients underwent radiofrequency ablation of AF and endomyocardial biopsy (EMB) with subsequent histological and immunohistochemical studies (IHC). Morphological verification of myocarditis was performed in accordance with the Dallas criteria modified by the World Heart Federation.Results. Signs of chronic myocarditis were identified in 64 patients (44.1%). The median age of patients with myocarditis was 44 (36.5;49) years, without myocarditis — 46 (38;51) years. In men, myocarditis was detected in 50 cases (42%), in women — in 14 (51.9%). In paroxysmal AF, myocarditis was detected in 25 patients (41.7%), in persistent AF — in 23 (41.8%), and in long-term persistent AF — in 16 (53.3%). The groups with and without chronic myocarditis were comparable when compared based on the main echocardiographic parameters. Regression analysis did not show a significant influence of these factors on the probability of detecting chronic myocarditis in patients with AF. In patients under 30 years of age, there were no signs of inflammation without the presence of myocardial fibrosis, while the maximum stage of fibrosis occurred in patients from 31 to 40 years of age. The stage of fibrosis did not depend on gender. More often than others, a combination of enterovirus and herpes virus type 6 was detected in biopsy specimens. In patients over 51 years of age, biopsies generally did not express any virus on immunohistochemical studies.Conclusion. Chronic myocarditis in patients with AF was significantly more often detected in younger patients (up to 50 years inclusive), and was more common in women, as well as in the presence of a long-term persistent form of AF, regardless of gender. Detection of myocardial fibrosis signs is more typical for young patients with the maximum stage at the age of 31 to 40 years.