Aim. To identify predictors of sinus rhythm restoration during radiofrequency ablation (RFA) in patients with persistent atrial fibrillation (AF).

Methods. The study included 51 patients with persistent AF who underwent primary RFA. All patients underwent left atrial (LA) voltage mapping. The percentage of low-voltage areas (LVA%) was calculated, with a low-voltage threshold 0.5 mV. After pulmonary vein isolation (PVI), if AF persist, posterior wall isolation and mitral isthmus ablation were performed. In cases of persistent AF, LA electrophysiological mapping was performed using a multielectrode catheter to identify areas of fractionated signals and local re-entry, followed by ablation of these areas. If AF transformed into atrial flutter, activation mapping was performed to verify the arrhythmia mechanism and ablate the critical isthmus. If the AF rhythm persisted, electrical cardioversion was performed.

Results. Sinus rhythm was restored during RFA in 29 patients (56.8%) and by electrical cardioversion in 22 patients (43.2%). Statistically significant differences between rhythm restoration types were found in AF duration (p=0.013; AUC=0.705) and LA appendage flow velocity (p=0.021; AUC=0.697). Patients who achieved rhythm restoration at the PVI stage had significantly smaller LA volume (p=0.004; AUC=0.796) and LVA% (p=0.002; AUC=0.792). In the group of patients in whom AF was eliminated by direct restoration to sinus rhythm during RFA, LVA% was significantly lower (p=0.039; AUC=0.738) compared with those in whom AF was eliminated via transformation into atrial flutter.

Conclusions. AF duration and LA appendage flow velocity are predictors of rhythm restoration during RFA. Among patients who achieved sinus rhythm restoration during ablation, those who converted at the PVI stage had smaller LA volume and LVA%. An LVA% greater than 28.5% was identified as a predictor of AF transformation into atypical atrial flutter during RFA of persistent AF.

Aim. To investigate the correlation between the efficacy of pulmonary vein ostial isolation and morphological changes in the myocardium.

Methods. The study included 118 patients with paroxysmal or persistent atrial fibrillation (AF) and no significant structural heart disease. All patients underwent primary cryoballoon isolation of the pulmonary vein ostia with simultaneous implantation of a loop ECG recorder (Medtronic Reveal XT) and myocardial biopsy of the interatrial septum (IAS) and the interventricular septum (IVS). Tissue samples were obtained before cryoballoon ablation (CBA). Patients were followed for one year with regular visits at 3, 6, and 12 months. If AF recurred, patients underwent a repeat electrophysiological study to assess the durability of pulmonary vein isolation. In cases of recovered pulmonary vein conduction, reisolation was performed, followed by another year of followup using the same visit schedule. Consequently, two patient groups were formed: those without AF recurrence (after one or two procedures) and those with recurrence (after two catheter isolation attempts).

Results. Owing to an insufficient number of representative IAS biopsy samples (the biopsy material mainly consisted of the fibrous portion of the IAS), the analysis of the relationship between IAS morphological changes and nonpulmonaryveindependent AF recurrence could not be performed. In IVS biopsy samples, the most common morphological findings were myocardial hypertrophy, loss of myocardial crossstriation, endocardial thickening and lipomatosis, and cardiomyocyte dystrophy.

Conclusion. In all AF patients without severe organic heart disease, various morphological changes of the IVS myocardium were identified, including fibrosis, lipomatosis, and dystrophy. Histological changes in myocardial biopsies from AF patients, such as cardiomyocyte degeneration and endocardial thickening, are important components of atrial remodelling that contribute to arrhythmia initiation, maintenance, and progression - consistent with the concept of atrial cardiomyopathy (atrial myopathy) regardless of its origin. A deeper understanding of these cellular and molecular changes may inform the development of novel targeted strategies for AF prevention and treatment. No clear predictors of a specific electrophysiological type of AF recurrence (pulmonaryveindependent vs. nonpulmonaryveindependent) after radiofrequency ablation were identified, which may reflect common underlying mechanisms and warrants further investigation.

Aim. To evaluate the efficacy of the class IC antiarrhythmic drug flecainide in combination with an atrioventricular nodal slowing agent (metoprolol succinate or diltiazem) for the suppression of refractory to other antiarrhythmic medication atrial fibrillation (AF) in patients with symptomatic paroxysmal AF without significant structural heart disease, as well as to assess the incidence of adverse events associated with this therapy.

Material and Methods. This multicenter observational study enrolled patients aged 18-75 years with documented symptomatic (EHRA class ≥2a) paroxysmal AF and frequent episodes (≥2 per month). All patients received flecainide combined with either metoprolol succinate or diltiazem. The primary endpoint was a documented episode of AF within 3 months of therapy. Secondary endpoints included time to AF recurrence and treatment-related adverse events. Rhythm monitoring was performed using a portable device for self-recording of lead I electrocardiograms: daily during the first week, twice weekly during weeks 2-4, and additionally on an ad hoc basis when symptoms occurred. Quality of life was assessed using the EQ-5D questionnaire at baseline and at study completion.

Results. The study included 59 patients (57.6% female; mean age 63.5±9.9 years). The combination of flecainide with metoprolol succinate was prescribed to 93.2% (n=55) of patients, and flecainide with diltiazem to 6.8% (n=4). The primary endpoint was reached in 33.9% of patients (n=20). The majority of AF recurrences (85% of all events, n=17) occurred during the first month of follow-up. Adverse events were reported in 10.2% of cases (n=7).

Conclusion. In patients with paroxysmal AF refractory to other antiarrhythmic drugs (including prior ineffective catheter ablation in half of the study patients), a combination of flecainide with metoprolol or diltiazem demonstrated a recurrence-free rate of 66% over 3 months, with an acceptable safety profile. Combination therapy is associated with a significant improvement in quality of life. Single-lead remote ECG monitoring is useful for detecting arrhythmia recurrences but is insufficient for a comprehensive assessment of the safety of intraventricular conduction disturbances.

Aim. To assess the long-term risk of life-threatening ventricular arrhythmias and recurrent systolic dysfunction in patients with chronic heart failure (CHF) and improved left ventricular ejection fraction (LVEF) following implantation of implantable cardioverter-defibrillators (ICD) or cardiac resynchronization therapy defibrillators (CRT-D) for primary prevention of sudden cardiac death (SCD), and to identify factors associated with these outcomes.

Methods. The study represents a continuation of the analysis of a previously described single-center retrospective cohort of patients with CHF and improved LVEF who had undergone ICD or CRT-D implantation for primary prevention of SCD. The study included 87 patients: 34 with ICDs and 53 with CRT-D. In contrast to the previously published work, which focused on survival, inappropriate electrical therapy, and complications related to implanted devices, the primary endpoint of the present study was the development of sustained ventricular arrhythmia terminated by ICD/CRT-D therapy (arrhythmic composite endpoint - ACE), while the secondary endpoint was relapse to an LVEF ≤35%.

Results. Duration follow-up after study inclusion was 5.2±2.8 years, and the total duration after device implantation was 8.3 ± 3.6 years. ACE was observed in 7.1% (n=6) of patients, and in 4.8% of those with persistently improved LVEF. Recurrent reduction in LVEF to ≤35% occurred in 24.4% (n=20) of patients and was associated with higher all-cause mortality (35.0% vs. 5.0%), presence of atrial fibrillation, more pronounced baseline left ventricular remodeling.

Conclusion. While a significantly reduced risk of life-threatening arrhythmias is observed upon improvement in LVEF, a certain risk of recurrent progression of systolic dysfunction persists. Despite the retrospective design and limited sample size, these results underscore the need for an individualized management approach for this patient category and provide a basis for planning further prospective studies in this field.

Aim. To evaluate the impact of the extent of left atrial (LA) low-voltage areas on the risk of atrial arrhythmia recurrence after radiofrequency ablation (RFA) in patients with atrial fibrillation (AF).

Methods. The study included 159 patients (mean age 65.36±9.33 years; 61.6% male) undergoing first-time RFA for AF (68.6% paroxysmal, 31.4% persistent). High-density LA voltage mapping was performed using a multielectrode catheter and CARTO 3 system. Areas with bipolar amplitude <0.5 mV were classified as low-voltage areas (LVA), and <0.1 mV as very low-voltage areas (vLVA). The percentage of LVA (LVA%) and vLVA% were calculated. The primary endpoint was recurrence of any atrial arrhythmia during 12-month follow-up. Kaplan-Meier survival analysis, Cox regression models, and ROC analysis were performed.

Results. Arrhythmia recurrence occurred in 40% of patients with persistent AF and 18.3% with paroxysmal AF. LVA% was significantly higher in patients with recurrence (40.40% vs. 4.80%; p < 0.001). In the Cox model, each 1% increase in LVA% was associated with a 3.6% higher recurrence risk (HR 1.036; p < 0.001). After adjustment for AF type and LA volume, LVA% remained an independent predictor (adjusted HR 1.034; p < 0.001). ROC analysis identified an optimal threshold of 22.4% (AUC=0.746). Patients with LVA% ≥22,4% had more than six-fold higher recurrence risk (adjusted HR 6.478; p < 0.001). LVA% measured during AF showed even stronger discrimination (AUC=0.786 for any arrhythmia; AUC=0.790 for atypical flutter/atrial tachycardia recurrence).

Conclusions. The extent of low-voltage substrate in the left atrium is a strong and independent predictor of arrhythmia recurrence after RFA. Thresholds of ≥22,4% (or ≥24,7% for mapping during atrial fibrillation) allow reliable risk stratification and may guide individualized ablation strategies.

Aim. To conduct a comparative analysis of the efficacy and safety of radiofrequency ablation (RFA) of pulmonary vein (PV) in patients with paroxysmal atrial fibrillation (AF) using a single-catheter method (experimental group) versus the standard technique with a multipolar diagnostic Lasso catheter (Biosense Webster, Johnson & Johnson, USA) (control group).

Methods. A single-center prospective randomized study included 206 patients with paroxysmal AF, randomized into two groups: single-catheter (n=103) and control (n=103). All procedures utilized the CARTO 3 (Biosense Webster, Johnson & Johnson, USA) 3D electroanatomical mapping system, and PV isolation was performed according to the CLOSE protocol based on the ablation index. In the experimental group, only a navigated ablation catheter was used for mapping and ablation, with verification of conduction block (entrance and exit) via stimulation from the ablation electrode. The control group underwent the standard approach with a circular diagnostic Lasso catheter. The primary endpoint was the absence of atrial arrhythmias (AF/atrial flutter) after 12 months of follow-up.

Results. Procedure efficacy after a median follow-up of 400 days was 83.5% (86/103 patients) in the single-catheter group and 78.7% (81/103) in the control group. The difference between groups was not statistically significant (OR 1.298; 95% CI 0.649-2.595; p=0.354). Kaplan-Meier analysis also revealed no significant differences (log-rank test, p=0.405). The first-pass PV isolation rate was comparable between groups (94.2% vs. 93.2%, p=0.874). The total procedure time was statistically significantly shorter in the single-catheter group (65.3±20.0 min vs. 82.2±13.0 min, p=0.011), while fluoroscopy time and RFA duration did not differ significantly. Three periprocedural complications were recorded (1 in the experimental and 2 in the control group), all of them were managed successfully.

Conclusion. Radiofrequency ablation of pulmonary veins using a single-catheter method is not inferior in efficacy to the standard approach utilizing a circular Lasso catheter in patients with paroxysmal atrial fibrillation. 

Aim. Evaluation of a patient group with a reduced percentage of stimulation, pain sensation, and the impact of adjusting stimulation programming parameters on achieving a positive effect from cardiac contractility modulation (CCM) therapy.

Methods. The study included 117 patients implanted with a CCM device. Personalized parameter settings were programmed intraoperatively and postoperatively. Transthoracic echocardiography (TTE) was performed before implantation and 6 months after surgery.

Results. The median age was 59.5 years, with 93.7% being male patients. The primary etiology of heart failure was ischemic heart disease (53.8%). A part of patients required a reduction in stimulation amplitude from 7.5 V (79%) to a maximum of 5 V (9%). After 6 months, the group with 7.5 V stimulation amplitude showed a significant increase in LVEF to 37 [32; 43] % (p=0.0001). However, in the group with 5 V stimulation amplitude, the increase in LVEF did not reach statistical significance during follow-up: 35 [34; 40] (p=0.211). Patients without discomfort during CCM therapy had lower LVEF (p=0.048), increased LV volumes (p=0.024; p=0.034), and a thinner LV posterior wall (p=0.028). However, the relationship between cardiac wall thickness and pain during ССМ therapy requires further research. Also, in patients without stimulation discomfort, the electrodes were more frequently implanted in the middle third of the interventricular septum (p=0.025). 83.7% of patients were programmed with standard stimulation duration - 7 hours per day (hrs/day). For 5.9%, the stimulation duration was 10 to 14 hours due to failure to achieve the required stimulation percentage. In this patient group, increasing the stimulation duration achieved a stimulation percentage exceeding 70%. In 15.3% of cases, patients with a CCM device had a therapy percentage above 90%. In 68.3% of cases, the daily therapy percentage was 80- 90%, and in 12% - 70 to 80%. A positive, moderate, significant correlation was noted between the stimulation percentage and the increase in LVEF (r=0.3; p=0.05).

Conclusion. CCM is an effective method of interventional treatment for patients with CHF. When programming CCM devices, it is necessary to achieve a stimulation percentage exceeding 70% per day, as the stimulation percentage directly correlates with an increase in myocardial contractility. Additionally, the stimulation amplitude should reach the target level of 7.5 V. If pain occurs, a reduction in stimulation amplitude to the minimum tolerable level is permissible. Further study of the nuances of device operation and training of specialists in programming intracardiac devices are necessary.

Aim. To evaluate the efficacy and safety of the prolonged-release formulation of lappaconitine hydrobromide at the minimum dose of 25 mg twice daily in patients with premature atrial contractions (PACs) and no structural heart disease. 

Methods. This retrospective open-label non-randomized observational study included 52 patients (20 men) aged 31-79 years with symptomatic PACs and/or paroxysmal atrial fibrillation requiring antiarrhythmic therapy. All patients underwent two Holter ECG recordings: before treatment initiation and after 2-3 weeks of therapy with prolonged-release lappaconitine hydrobromide 25 mg twice daily. All quantitative indices of atrial ectopic activity were normalized to 24 hours. Efficacy was assessed by changes in the number of single, paired, and grouped PACs, episodes of paroxysmal focal atrial tachycardia (AT), the ectopic burden index, and the distribution of responders. Safety was assessed by changes in heart rate, P-wave, QRS complex, PQ, QT and QTc intervals duration. Analysis of individual forms of atrial ectopic activity was performed only in patients in whom the corresponding types of arrhythmia were present at baseline and for whom complete data were available to assess their changes during therapy.

Results. Therapy was associated with a statistically significant reduction in all forms of atrial ectopic activity, including single PACs, paired PACs, grouped PACs, and episodes of paroxysmal focal AT (all p<0.001). In most patients, the reduction in arrhythmia frequency was ≥75%. A similar effect was observed in the subgroup with a high baseline PAC burden (>500 PACs per 24 hours). Heart rate decreased moderately; a statistically significant but clinically insignificant increase in the PQ interval was observed. No significant changes were found in P-wave duration, QRS duration, or QT and QTc intervals.

Conclusion. The prolonged-release formulation of lappaconitine hydrobromide at the minimum daily dose of 50 mg provides a statistically significant reduction in atrial ectopic activity in patients without structural heart disease and is characterized by a favorable safety profile when administered twice daily.

This review summarizes the anatomical and physiological characteristics of the sinoatrial node as a model for bio­ pacemakers and analyzes current approaches to their development, including sinoatrial node cell transplantation, the use of pluripotent stem cells, gene therapy (HCN overexpression, IK1 suppression, TBX18 transduction, and others), as well as combined and reprogramming strategies Special attention is given to the authors’ own experience and achievements in tissue engineering. Key obstacles to clinical translation are outlined, including safety concerns, stability of therapeutic effects, adequacy of experimental models, and control of biological pacemaker activity. Despite existing limitations, pro­ gress in gene engineering, stem cell technologies, and biomaterials offers promising opportunities for the development of fully physiological alternatives to electronic pacemakers.

This review article examines current approaches to the use of Stereotactic Arrhythmia Radioablation (STAR) in patients with sustained ventricular tachycardia refractory to medical therapy and catheter ablation. The biophysical and molecular mechanisms of the therapeutic action of the method, experimental data, principles of target planning and imaging, as well as international and our own clinical experience with the method in patients with ventricular tachycardias are presented. Technical aspects of the method, unresolved issues, limitations, and the potential for implementing STAR into Russian clinical practice are discussed separately.