Early initiation of anti-relapse antiarrhythmic therapy in patients with atrial fibrillation and flutter after pharmacological cardioversion with refralon.

Aim      Evaluating the efficacy and safety of early administration of antirecurrence antiarrhythmic therapy (AAT) following restoration of sinus rhythm (SR) with refralon.Aim      Evaluating the efficacy and safety of early administration of antirecurrence antiarrhythmic therapy (AAT) following restoration of sinus rhythm (SR) with refralon.Material and methods  The study included 247 patients with atrial fibrillation/atrial flutter (AF/AFL) (142 men) who underwent pharmacological cardioversion (PCV) with refralon. A 4-step schedule of drug administration was used (successive intravenous infusions at doses of 5, 5, 10, and 10 µg/kg; maximum total dose was 30 µg/kg). Patients who recovered SR and had no contraindications were prescribed antirecurrence AAT in the early (≤24 h; n=101) or delayed (≥24 h; n=95) period. Lappaconitine hydrobromide, propafenone, and sotalol were administered orally as the antirecurrence therapy. The decision on the time of initiating ATT and the choice of the drug and its dose was taken by the attending physician individually. The safety criteria included a prolonged PQ interval >200 ms; second- or third-degree atrioventricular block; QRS complex duration >120 ms; QT prolongation >500 ms; and heartbeat pauses >3 s. The efficacy criteria included the absence of sustained recurrence of AF/AFL after initiation of AAT and the duration of hospitalization after PCV. Patients were followed up during the study until they were discharged from the hospital.Results SR was recovered in 229 (92.7 %) patients. In the group of early AAT initiation, a PQ duration >200 ms was observed in 8 (7.9 %) patients, whereas in the group of delayed AAT initiation, in 7 patients (7.4 %; p=1.000). A wide QRS complex >120 ms was recorded in 1 (1.1 %) patient of the delayed AAT initiation group and in none of the patients of the early AAT initiation group (p=0.485). Ventricular arrhythmogenic effects and QT prolongation >500 ms were not detected in any patient. Numbers of early AF recurrence did not differ in the groups of early and delayed AAT initiation: 6 (5.9 %) vs. 5 (5.3 %), respectively (p=1.000). Median duration of hospitalization after PCV was 4 days in the group of early AAT initiation and 5 days in the group of delayed AAT initiation (р=0.009).Conclusion      Early initiation of the refralon AAT does not increase the risk of drug adverse effects and reduces the duration of stay in the hospital.

[Left bundle branch block - dilated cardiomyopathy - heart failure: common links in the closed pathogenetic chain].

This review summarizes the available information on the epidemiology and prognosis of patients with left bundle branch block (LBBB), morphological alterations of the myocardium both resulting in and ensuing LBBB, cardiac biomechanics in LBBB, and possibilities of its correction.

[Efficiency and safety of using the modified protocol for the administration of the domestic class III antiarrhythmic drug for the relief of paroxysmal atrial fibrillation].

AIM: Evaluation of the efficacy and safety of the modified refralon administration protocol for the relief of paroxysmal atrial fibrillation (AF). MATERIALS AND METHODS: The study included 39 patients (19 men, mean age 6312.8 years). All patients, after excluding contraindications in the intensive care unit, were injected intravenously with refralon at an initial dose of 5 mg/kg. If AF was preserved and there were no contraindications, after 15 min, repeated administration was performed at a dose of 5 mg/kg (total dose of 10 mg/kg). After another 15 min, while maintaining AF and the absence of contraindications, the third injection of the drug was performed at a dose of 10 mg/kg (total dose of 20 mg/kg). In the absence of relief and the absence of contraindications, another injection of refralon at a dose of 10 mg/kg was performed after another 15 min (in this case, the maximum total dose of 30 mg/kg was reached). After each injected bolus and before the introduction of the next one, the ECG parameters and the general condition of the patient were assessed. The patient was monitored for 24 hours to exclude the arrhythmogenic effect and other possible adverse events. RESULTS: Restoration of sinus rhythm (SR) was noted in 37 patients out of 39 (95%). Of these, 19 people (48.7%) had SR recovery after the administration of a minimum dose of refralone of 5 mg/kg. The effectiveness of the total dose of 10 mg/kg was 76.9%, the dose of 20 mg/kg was 89.7%, and the dose of 30 mg/kg was 95%. Only two patients did not recover HR after administration of the maximum dose of refralon 30 mg/kg. Pathological prolongation of the QTc interval (500 ms) was recorded in 5% of patients. Not a single case of ventricular arrhythmogenic action (induction of Torsade de pointes) has been reported. Bradyarrhythmias (pauses, bradycardia) were registered in 13% of cases, were of a transient nature. CONCLUSION: Refralon has a high efficiency of relief (95%) of paroxysmal AF, while in almost half of cases (48.7%), SR recovery is achieved using the minimum dose of refralon 5 mg/kg. Despite the prolongation of the QTc500 ms recorded in 5% of cases, none of the patients developed Torsade de pointes after administration of the drug.

[Adherence and efficacy of long-term PAP therapy in patients with sleep-related breathing disorders associated with cardiac conduction disorders].

AIM: To study the effectiveness of prolonged use of PAP therapy (positive airway pressure therapy) in eliminating sleep respiratory disorders and associated cardiac conduction disturbances. MATERIALS AND METHODS: We included 21 patients who were examined at the Myasnikov Institute of Clinical Cardiology, National Medical Research Center of Cardiology, regarding cardiac rhythm and conduction disturbances, as well as obstructive sleep apnea and who have been on PAP therapy for more than 12 months. The average age was 66.5 [63.5; 73.2] years, body mass index 33.0 [30.2; 38.5] kg/m2, apnea-hypopnea index 65.0 [59.0; 86.3]/h. At the time of analysis, 15 patients continued to use PAP therapy (mean time of use: 6.0 years [4.7; 9.2]) and 6 patients refused long-term use of PAP therapy, mean time to use PAP therapy until failure amounted to 2.82.1 years. RESULTS: PAP therapy lead to a persistent decrease in apnea-hypopnea index of 63.6/h to 3.7/h was (p=0.0002). 86% of patients met the criteria for adherence to PAP therapy (use 4 hours/night, more than 70% of nights). Initially, before the use of PAP therapy, all cardiac conduction disorders were during sleep and exceeded 3 seconds, with fluctuations from 3.1 to 10.6 seconds. PAP therapy appeared to be effective in all patients: no asystoles, duration of more than 3 seconds, were detected. CONCLUSION: In obstructive sleep apnea patients with concomitant nighttime cardiac conduction disturbances, the long-term use of PAP therapy is effective and with good adherence.

[Cardiac magnetic resonance imaging with contrast enhancement in treatment of atrial fibrillation].

Catheter ablation is presently the main method for interventional treatment of atrial fibrillation (AF). Despite improvements of the method and accumulation of personnel's experience, incidence of recurrent AF following catheter interventions remains high. This review addresses a possibility of using contrast-enhanced cardiac magnetic resonance imaging to increase the effectiveness of interventional treatment of arrhythmia.

[Assessment of myocardial electrical dissynchrony by noninvasive activation mapping and its role in achieving the success of cardiac resynchronization].

PURPOSE: To assess and to compare the ventricular myocardium activation patern obtained by non-invasive epi- and endocardial mapping (NIEEM), as well as electrocardiographic (ECG) variants of lef bundle branch block (LBBB) and to estimate the value of these data for the success of cardiac resynchronization therapy (CRT). MATERIALS AND METHODS: Te study included 23 patients (mean age 59,6±9,9 years) with LBBB, QRS duration ≥ 130 ms, lef ventricular ejection fraction (LVEF) ≤ 35%, heart failure (HF) NYHA II-IV despite optimal pharmacological therapy during 3 month. All patients had undergone CRT-D implantation. Depending on presence or absence of LBBB ECG-criteria, proposed by Strauss D.G. et. al, patients were divided into 2 groups: 1group - strict LBBB, proposed by Strauss D.G. et. al. (n=14) and 2 group - other ECG morphologies of LBBB (n=9). NIEEM by the Amycard 01C system with an analysis of epi- and endocardial ventricular electrical activation was performed in all patients and 5 healthy volunteers (mean age 29±1,0years). Response to CRT was estimated by echo and was defned as decrease in lef ventricular (LV) end-systolic volume by > 15% afer 6 months of follow-up. RESULTS: LBBB ECG-criteria, proposed by Strauss D.G. et. al, was detected in 14 patients (61% of all included). According to the results of NIEEM, these patients had more pronounced ventricular electrical uncoupling (VEU) (р=0,002). Most ofen the line of block was detected in the anteroseptal or posterolateral region of the LV. Te zone of late LV activation, which is the most optimal position for the LV pacing electrode, was located in the basal and middle segments of the lateral and posterior walls. Afer 6 months of CRT 15 patients (65%) were included in the "response" group, the remaining 8 patients (35%) formed the "non-response" group according to echo criteria. In the "response" group the morphology of the QRS complex more frequently met the criteria, proposed by Strauss D.G. et al, than other ECG variants of LBBB (12 vs. 3 respectively, p = 0.023). Initially, VEU was more pronounced in the "response" group (VEU 55 [51, 64] ms in the "response" group vs 22 [8, 38] ms in the "non-response" group).Сonclusions. LBBB ECG criteria, proposed by Strauss D.G., identify patients with delayed transseptal interventricular conduction due to complete LBBB, what is a good target for CPT. Identifcation of individual ventricular activation properties may help to reveal responders to CRT in patients with LBBB.

The value of cardiovascular magnetic resonance in myocarditis with different clinical presentation.

AIM: to assess the diagnostic meaning of cardiac magnetic resonance imaging (CMR) in various clinical forms of myocarditis. MATERIALS AND METHODS: 11 (8 men, mean age 32.8±11.1 years) patients (pts), hospitalized with suspected acute coronary syndrome, while an acute myocardial infarction was excluded during the examination (group I); 48 pts (31 men, 43.1±12.7 years), with clinical and instrumental signs of dilated cardiomyopathy (DCM) - group II; and 20 patients (12 men, 39.5±14 years), with episodes of ventricular tachycardia (group III) underwent cardiac magnetic resonance imaging (CMRI). In 38 patients endomyocardial biopsy (EMB) was performed. RESULTS: According to EMB, signs of active myocarditis were revealed in 10 (34.5%) group II pts and in 3 (37.5%) group III pts; signs of resolved myocarditis - in 8 (27.6%) patients in group II and in 3 (37.5%); minimal morphological changes - in 11 (37.9%) patients of group II and in 2 (25%) patients of group III. In 9 (81.9%) patients of group I MRI data allowed to establish the diagnosis of acute myocarditis. Signs of active inflammation from MRI data were detected in myocardium 5 (10.4%) in group II pts and 7 (35%) in group III pts. In 22 (45.8%) pts in group II and 10 (50%), CMR data corresponded to the picture of resolved myocarditis. In 21 (43.8%) cases of group II and 3 (15%) of group III, MRI revealed minimal structural changes. In pts with clinical and instrumental signs of DCM and/or ventricular tachycardia MRI allows to identify signs of "active myocarditis" with a sensitivity of 37.5% with a specificity of 83.4%. At the same time, in cases of resolved myocarditis and minimal morphological changes MRI has high sensitivity (70 and 71.5%) and specificity (71.5 and 75%, respectively). CONCLUSION: CMR has high diagnostic significance in patients with infarct-like course of myocarditis. In patients with clinical syndrome of dilated cardiomyopathy or arrhythmias, the sensitivity of MRI in detecting active myocarditis is low (37.5%) with high specificity (83.4%). In cases of minimal structural changes in the myocardium and resolved inflammation, CMR is a good alternative to EMB.

[Comparative efficacy and safety of enoxaparin followed by warfarin and rivaroxaban monotherapy in the treatment of venous thrombosis in patients after intracardiac catheter interventions].

AIM: to compare two anticoagulant therapy (ACT) regimens in the treatment of venous thrombosis (VT) in patients after catheter interventions - electrophysiological studies (EFIs) and ablations: enoxaparin followed by warfarin, and rivaroxaban monotherapy. MATERIALS AND METHODS: The study included patients from 18 years and older with heart rhythm disorders and planned catheter ablation. When parietal venous thrombosis (VT) were detected at the femoral vein puncture site, all patients were randomly assigned to two treatment groups. In group I enoxaparin 1 mg/kg was prescribed every 12 hours with switching to warfarin after 7 days with maintenance of the target INR values (2.0-3.0). In group II rivaroxaban therapy was started at a dose of 15 mg twise/day for 21 days with a further transition to a dose of 20 mg/day. The total period of observation and treatment of patients was at least 3 months. RESULTS: 408 patients were observed, 42 (10.3%) patients with parietal VT were divided into two treatment groups. In group I (n=16) complete lysis of VT was noted by the 7th day of treatment in 7 (58.3%) patients, however this scheme was associated with a greater risk of complications (р=0.003) at the puncture site in the form of arteriovenous fistulae (n=1; 8.3%) and intermuscular hematomas (n=4; 25%). In group II (n=26), no complications were noted, the lysis time of VT was on average 21 days (n=18; 69.2%). Complete lysis of VT was noted in both groups at the time of the control observation point (3rd month). CONCLUSION: The efficiency of the two VT treatment regimens was comparable. Enoxaparin therapy is associated with a high risk of local complications, namely intermuscular hematomas (n=4; 25%) and arteriovenous fistulas (n=1; 8.3%). Rivaroxaban monotherapy is safer (p=0.003); in Group II none of the patients had any complications.

[Autoantibodies to M2-cholinoreceptors as a potential development factor of arrhythmia in patients with paroxysmal atrial fibrillation].

AIM: We aimed to assess autoantibodies to M2-cholinoceptors (M2-CR) in patients with paroxysmal lone atrial fibrillation (AF) and in patients with AF and arterial hypertension (AH). MATERIALS AND METHODS: 100 patients with lone AF and 84 patients with AF and AH were included. Patients underwent clinical blood and urinalysis, assessment of biochemistry blood panel, 12-lead ECG, 24-hour Holter monitoring, echocardiography and stress - testing (treadmill or stress - echocardiography). Assessment of IgM and IgG autoantibodies to M2-CR was performed by indirect immunoenzyme assay. The following peptide molecules were used as epitopes for detection of autoantibodies: M1 - amino acid sequence YTVIGYWPLGVVCDL (83-98) of the first extracellular loop of M2-CR; M2 - sequence VRTVEDGECYIQFFSNAAVTFGTAI (168-192) of the second extracellular loop of M2-CR; M3 - sequence NTFCAPCIPNTV (410-421) of the third extracellular loop of M2-CR; M4 - short sequence VEDGECYIQFFS (171-182) of the second extracellular loop of M2-CR; M1+M4 - chimeric molecule formed by sequences of the first and the second extracellular loops of M2-CR connected by disulfide bound YTVIGYWPLGVVCDL + VEDGECYIQFFS (83-98 + 171-182). RESULTS: Autoantibodies to M2-CR were found in 45% patients with lone AF and in 35% patients with AF and AH. In patients with lone AF prevalence of increased IgG to M2-CR were greater than in patients with AF and AH (32% vs 20%; p.

[Recent advances in diagnosis and management of atrial fibrillation].

Alterations of heart rhythm are a common clinical event. They can be caused by almost any kind of heart disorder. Atrial fibrillation (AF) is the most common type of abnormal heart rhythm. Prevalence of AF in the general population is 1-2%, and given that AF incidence rate continues to increase it can be predicted that the number of patients will be doubled within the next 50 years. This review provides the most recent diagnostic and treatment methods, including both unique domestic antiarrhythmic drugs and non - drug methods for AF treatment which were developed and implemented in clinical practice at NMRC of Cardiology of the Ministry of Health of the Russian Federation.

Role of electrocardiographic and echocardiographic types of left bundle branch block in prediction of response to cardiac resynchronization therapy.

AIM: To assess the value of the complex analysis of electrocardiographic (ECG) variants and echocardiographic (echo) manifestation of left bundle branch block (LBBB) in predicting the success of cardiac resynchronization therapy (CRT). MATERIALS AND METHODS: The study included 39 patients (mean age 61.49±9.0 years) on sinus rhythm with LBBB, QRS duration ≥130 ms, left ventricular ejection fraction (LVEF) ≤35%, heart failure (HF) NYHA II-IV despite optimal pharmacological therapy during 3 month. All patients had undergone CRT-D implantation. Depending on presence or absence of ECG-criteria, proposed by D.G. Strauss et al., patients were divided into 2 groups: 1 group - strict LBBB, proposed by D.G. Strauss et al. (n=29) and 2 group - other patients (n=10). In addition to standard echocardiography, global longitudinal 2-dimensional strain (GLS) and LBBB contraction pattern have been performed initially and in 6 months after implantation. Response to CRT was defined as decrease in LV end-systolic volume by >15% after 6 months of follow-up. RESULTS: Typical LBBB echo contraction pattern was detected in 25 patients (64% of all included). These patients had more pronounced longitudinal dissynchrony and a more expressed global longitudinal strain before CPT-D implantation (p<0.05). 27 patients (69% of all included) were included in the "response" group, the remaining 12 patients (31% of all included) - the "non-response" group. In the "response" group the morphology of the QRS complex was significantly more likely to meet the criteria, proposed by D.G. Strauss et al., than other variants (23 vs. 6, respectively, p=0.02), and the echo contraction pattern of this patients more often corresponded to "typical" LBBB (24 vs. 1, p=0.001). All patients, who had the ECG criteria, proposed by D.G. Strauss et al., and echo "typical" LBBB contraction pattern, responded on CPT. Moreover, the proportion of these patients in the "response" group was rather high - 81.5% (22 of 27 patients). CONCLUSION: ECG criteria LBBB, proposed by D.G. Strauss et al., identify patients with delayed transseptal interventricular conduction due to complete LBBB, what is a good target for CPT. Evaluation of the echo contraction pattern based on the definition of longitudinal myocardial deformation by means of a two-dimensional strand technology allows predicting the success of CPT in patients with LBBB. Patients with «typical¼ LBBB contraction pattern show more pronounced global longitudinal strain and larger longitudinal dissynchrony compared with other patients, and it explains their better response to CPT. Complex analysis of strict LBBB ECG criteria and echo contraction pattern are promising parameters in predicting beneficial response to CRT in patients with HF.

Review of New American Heart Association/American College of Cardiology/Heart Rhythm Society Guideline for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death.

In this brief review we focus on major updates and key points of 2017 American Heart Association/American College of Cardiology/Heart Rhythm Society (AHA/ACC/HRS) guideline for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death.

Structural and Functional Properties of the Left Atrium in Healthy Volunteers and Patients With Atrial Fibrillation: Data of Magnetic Resonance Imaging.

BACKGROUND: In the recent years, there has been an increasing number of publications postulating that data on left atrial (LA) structure obtained by late gadolinium enhancement magnetic resonance imaging (LGE MRI) can improve the management of patients with atrial fibrillation (AF). At the same time, similar data regarding healthy LA myocardium is limited. AIM: To assess structural and functional properties of LA in healthy volunteers (HV) using cardiac magnetic resonance (CMR) (including LGE MRI); to compare these properties in patients with AF and HV. MATERIALS AND METHODS: We included in this study 53 patients with AF (28 without signs of cardiovascular disease, 28 with hypertension) and 23 HV of similar age. All enrolled persons underwent MRI. Cine-MRI was used to assess end diastolic volume of LA (LA EDV), LA ejection fraction (LA EF), left ventricular diastolic index (LV DI). High resolution LGE MRI was performed 15-20 min after gadoversetamide injection using IR 3D gradient echo pulse sequence with fat saturation (TI 290-340 ms, TE 2.44 ms, TR 610-1100ms). On obtained images LA was segmented semiautomatically. LA fibrosis quantification was performed using developed software LGE Heart Analyzer. The extent of fibrosis was represented as percent of LA myocardium volume. Fibrosis location was determined on reconstructed rotating 3D LA model. RESULTS: Compared with patients HV had lower LA EDV (59 [54; 78] ml and 79 [65.5; 86.6] ml, р=0.043, respectively), higher LA EF (56.1 [49; 63.2] % and 44.5 [34.5, 54.5] %, р=0.03, respectively), and lower extent of LA fibrosis (0.7 [0.05; 3.5] % and 9.1 [1.7; 18] %, р.

[Restoration of Sinus Rhythm in Patients With Persistent Atrial Fibrillation and Obesity: New Possibilities of Pharmacological Cardioversion].

We present in this article 2 cases of successful pharmacological restoration of sinus rhythm by a new class III antiarrhythmic drug refralon in patients with obesity and persistent atrial fibrillation. In both cases, the effective use of refralon was preceded by repeated ineffective attempts of electrical cardioversion. In the article we discuss the role of obesity as the factor leading to a substantial increase of transthoracic electrical resistance, and thus significantly reducing the probability of sinus rhythm restoration by means of electrical cardioversion. The clinical examples described in this article clearly show that the use of refralon may represent a unique clinical alternative to electrical cardioversion for sinus rhythm restoration in patients with persistent atrial fibrillation, and in some cases where the success of electrical cardioversion is obviously questionable, like in patients with severe obesity, the use of refralon seems preferable.

[Structural and Functional Properties of the Left Atrium in Healthy Volunteers and Patients With Atrial Fibrillation: Data of Magnetic Resonance Imaging].

BACKGROUND: in the recent years, there has been an increasing number of publications postulating that data on left atrial (LA) structure obtained by late gadolinium enhancement magnetic resonance imaging (LGE MRI) can improve the management of patients with atrial fibrillation (AF). At the same time, similar data regarding healthy LA myocardium is limited. AIM: to assess structural and functional properties of LA in healthy volunteers (HV) using cardiac magnetic resonance (CMR) (including LGE MRI); to compare these properties in patients with AF and HV. MATERIALS AND METHODS: We included in this study 53 patients with AF (28 without signs of cardiovascular disease, 28 with hypertension) and 23 HV of similar age. All enrolled persons underwent MRI. Cine-MRI was used to assess end diastolic volume of LA (LA EDV), LA ejection fraction (LA EF), left ventricular diastolic index (LV DI). High resolution LGE MRI was performed 15-20 min after gadoversetamide injection using IR 3D gradient echo pulse sequence with fat saturation (TI 290-340 ms, TE 2.44 ms, TR 610-1100ms). On obtained images LA was segmented semiautomatically. LA fibrosis quantification was performed using developed software LGE Heart Analyzer. The extent of fibrosis was represented as percent of LA myocardium volume. Fibrosis location was determined on reconstructed rotating 3D LA model. RESULTS: Compared with patients HV had lower LA EDV (59 [54; 78] ml and 79 [65.5; 86.6] ml, р=0.043, respectively), higher LA EF (56.1 [49; 63.2] % and 44.5 [34.5, 54.5] %, р=0.03, respectively), and lower extent of LA fibrosis (0.7 [0.05; 3.5] % and 9.1 [1.7; 18] %, р.

[Changes in the receptor activity of ß2-adrenoreceptors of human T-lymphocytes under the effect of ß2-agonists].

Changes in the activity of ß2-adrenergic receptors of human T-lymphocytes under the effect of salbutamol (a short-acting ß2-agonist) have been evaluated with a new modified radioligand method utilizing [^(125)I]cyanopindolol and a specific ligand ICI 118551. In healthy volunteers, the receptor activity decreased after 30 min upon the inhalation of salbutamol and restored to the initial level after 2 h. At the same time, there were changes in the transcription level of the ADRB2 gene, which encodes the protein component of the ß2-adrenoreceptor. The dynamics of ß2-adrenergic receptor activity of T-lymphocytes after salbutamol treatment in patients with cardiorespiratory pathology significantly differed from that in healthy volunteers.

[Role of Autoantibodies Against 1-Adrenergic Receptor in Cardiovascular Disease].

According to current knowledge, autoantibodies against 1-adrenergic receptors may be involved in pathogenesis of different cardiovascular diseases and are mostly studied in patients with Chagas disease, dilated cardiomyopathy and heart rhythm disorders. They may play an important role in cardiomyocyte apoptosis, alteration of their chrono- and inotropic effects and electrophysiological characteristics. Their effects are transduced via 1-adrenergic receptors and depend on multiple factors as ligand properties, durability of its coupling with the receptor, amount of receptors on the cell surface, their affinity and conformation. Up to the present moment, reasons for autoimmune response and clinical significance of autoantibodies against 1-adrenergic receptors are not thoroughly understood. Autoantibodies against 1-adrenergic receptors can be removed from the bloodstream by immunoadsorption and thus development of validated methods of their identification is relevant.

[Detection of Autoantibodies Against the 1-Adrenergic Receptor in the Sera of Patients via the Competitive cell-Based Enzyme Linked Immunosorbent Assay].

OBJECTIVE: This study aimed to assess the level of anti-1-adrenergic receptor autoantibodies in patients with ventricular arrhythmias with no signs of organic heart disease and with presence of cardiovascular pathology in comparison with a group of healthy volunteers. MATERIAL AND METHODS: The study included 44 patients with ventricular arrhythmias with no signs of organic heart disease ("idiopathic"), 34 patients with diagnosed dilated cardiomyopathy (DCM) of inflammatory origin, 35 patients with coronary heart disease and ventricular arrhythmias, 12patients with coronary heart disease with no ventricular arrhythmias, and 19 healthy volunteers (control group). The level of autoantibodies against the 1-adrenergic receptor was determined by the developed competitive cell-based enzyme-linked immunosorbent assay (ELISA) and by the standard ELISA using peptides corresponding to the second extracellular loop of the 1-adrenergic receptor. RESULTS: Elevated level of autoantibodies detected by a competitive cell-based ELISA was observed in 62% of patients with DCM compared to 21% of healthy volunteers (p=0.0006). In patients with "idiopathic" ventricular arrhythmias, the level of 1-adrenergic receptor autoantibodies was lower than in healthy subjects (p=0.003). Coronary heart disease patients with or without ventricular arrhythmias exhibited no differences from the control group. The number of significantly positive signals in peptide-based ELISA did not exceed 10% in any of the groups. No correlation between the data from competitive cell-based ELISA and peptide-based ELISA was found. CONCLUSIONS: This study demonstrated that competitive cell-based ELISA technique can be applied for detection of 1-adrenergic receptor autoantibodies. The results in DCM patients generally correspond to the expected. Decreased level of autoantibodies in patients with "idiopathic" ventricular arrhythmias indicates that this disease is related to changes in the immune system. Such relation is not observed in the case of coronary heart disease patients.