Clinical Investigation to Evaluate the Effectiveness and Safety of ECG App

Inclusion Criteria: 1. Patients over 18 years old, regardless of gender; 2. Participants who meet one of the following conditions according to the medical history in the past 3 months or the ECG during the screening period: 1. Patients with normal sinus rhythm; 2. Patients with persistent or permanent paroxysmal atrial fibrillation or in the onset of paroxysmal atrial fibrillation; 3. Patients with frequent premature beats (more than 5 per minute) or in the onset of premature beats; 3. Patients who have good compliance, and can cooperate to complete this research by himself/herself; 4）Patients who volunteer to participate and have signed an informed consent form. Exclusion Criteria: 1. Patients using cardiac pacemakers or implantable cardioverter defibrillators (ICD); 2. Patients with atrioventricular block or bundle branch block; 3. Patients with significant sinus arrhythmia, sinus arrest or sick sinus syndrome; 4. Patients with interpolated premature beats, junctional premature beats, or escape rhythms; 5. Patients with atrial tachycardia, atrial flutter, ventricular tachycardia, ventricular flutter, or ventricular fibrillation; 6. Patients with a resting heart rate of slower than 50 beats/minute or faster than 110 beats/minute; 7. Patients with atrial fibrillation complicated with premature beats; 8. Patients who are critically ill, making it difficult to make an accurate assessment of the effectiveness and safety of the device; 9. Patients who suffer from tremor diseases or chorea, making it difficult to complete the examination quietly; 10. Patients with bullous diseases or large-area skin rashes that are not suitable for body surface electrode recording; 11. Patients whose skin is allergic to ethanol; 12. Patients with contagious skin diseases; 13. Patients with a history of mental illness or with cognitive impairment; 14. Patients who have participated in other clinical investigations within the past 30 days that may affect this investigation; 15） Other conditions that the investigators consider inappropriate for participation in the investigation.