Patients with cardiac pathology and arrhythmias including those who have indications for pacemakers implantation will be included in the study. We will determine the influence of pacemaker implantation with the localization of the ventricular electrode in the top of the right ventricle or the middle third of the right ventricle according to echocardiographic and electrocardiographic parameters, congestive heart failure progression, patients' quality of life and follow-up therapy of patients with identified myocardial fibrosis with existing pacemaker.

Study of changes in echocardiography, electrocardiography, myocardial fibrosis markers, the quality of life of patients will allow to choose the most optimal localization of the ventricular electrode during implantation of the permanent pacemakers system in order to improve the quality of life of the patients.

Anticipated design of the study: an open, prospective, study, with parallel groups of patients according to ICH GCP ((International Conference on Harmonisation - Good Clinical Practice) criteria.

The study will involve 300 patients with cardiac pathology and arrhythmias including those who have indications for pacemakers implantation, who will be allocated into 2 groups: group 1 - patients who require a permanent pacemaker placement; group 2 - patients who do not require a permanent pacemaker placement.

Patients involved in the study will undergo peripheral venous blood sampling to determine the level of myocardial fibrosis markers (Halitin-3, ST2), electrocardiography (assessment of the type of bradyarrhythmia, assessment of the presence/absence and type of intraventricular conductivity disorder, estimation of the width of the QRS complex, direction of the electric axis of the heart), echocardiography (evaluation of ejection fraction, heart chamber size, mitral and tricuspidal manifestation, interventricular delay), contrast-enhanced cardiac magnetic resonance imaging (MRI), quality of life assessment using the Aquarel questionnaire. All procedures will be repeated at time points as per protocol.

Specific information for Group A patients: there will be different variants of localization of the right ventricular lead (top of the right ventricle, the upper third of the ventricular septum, the middle third of the ventricular septum, the lower third of the ventricular septum, front wall of the right ventricle, lower wall of the right ventricle, parahisial region, His bundle). The analysis of the subgroups will be carried out according to the following criteria: electrode localization, main indication for pacemakers implantation, pacemakers model, type of initial intraventricular conductivity disorder.

Inclusion Criteria:

1. men or women over 60 years of age
2. . signed informed consent form
3. . presence of cardiac pathology and arrhythmia requiring pacemakers implantation (group A).
4. . presence of cardiac pathology and arrhythmia not requiring pacemaker implantation (group B).

Exclusion Criteria:

1. . active cancer or remission period less than 5 years;
2. . decompensated somatic pathology;
3. . active viral hepatitis, HIV or syphilis;
4. . men or women younger than 60 years of age or older than 85 years of age;
5. . withdrawn consent.

150 patients with cardiac pathology and arrhythmia not requiring pacemaker implantation and 150 patients with cardiac pathology and arrhythmia requiring pacemaker implantation (with different localization of the right ventricular lead).