Determination of Diastolic Dysfunction by Single Lead Electrocardiogram

Inclusion Criteria: * The presence of written informed consent of the patient to participate in the study * Age from 18 years to 90 years * Outpatient treatment and / or hospitalization in a research center Exclusion Criteria: * Reluctance of the patient to participate in the study * Poor quality ECG recording on a single-channel ECG monitor * Poor visualization of the heart during echocardiographic study * Acute psychotic reactions that arose during research * An exacerbation of chronic diseases requiring treatment tactics for the patient and preventing his further participation in the study. Non-inclusion criteria: * The presence of conduction disturbances in patients that impede ECG analysis (WPW syndrome, sinoatrial block of degrees 2 and 3, atrioventricular block 3 degrees, complete block of the left bundle branch block, complete block of the right bundle branch block) * Conditions that can impair ECG recording quality (Parkinson's disease, essential tremor) * The inability to assess diastolic function during echocardiography * Mental illness * Diseases with an expected life expectancy of less than 2 years * Patients with diffuse hypokinesis of the left ventricle with a reduced ejection fraction (less than 30%) * Patients with a pacemaker installed