Atrial fibrillation (also known as AFib or AF) is the most common abnormal heart rhythm and results in an irregular beating of the heart. Currently, there is no way of identifying patients at most risk for the development or progression of AFib or those that will best respond to treatment. The purpose of this study is to improve our understanding of AFib and to find new ways of identifying those patients most at risk for developing AFib, have progressive AFib or be less responsive to treatment. For this reason, the investigators are studying imaging, blood, and digital markers that may contribute to AFib

Subjects will receive mobile devices (uch as an AliveCor Kardia and a VivaLnk Wearable ECG patch or similar devices) for remote electrocardiographic (ECG) monitoring. Additionally, subjects will use features using a smartphone research app (on the Eureka Research Platform) to monitor other important things such as activity, sleep, heart rate and others as they are developed. All subjects will receive serial blood draws and saliva sample collections once a year. Subjects will also undergo annual imaging in the form of an echocardiogram (Echo). Evaluations will be taken at baseline and once a year for three years from the baseline visit. Additionally, electronic surveys will be administered periodically (eVisits occurring every 3-6 months) using the mobile app.

This is a single center, longitudinal, observational cohort study. 3000 subjects are planned to be enrolled. Each subject will be consented, enrolled and assigned to a group based on AF diagnosis (AF Group, AF Risk Group and Control Group). All subjects will be given mobile devices (such as an AliveCor Kardia and a VivaLnk Wearable ECG patch or similar devices) for remote ECG monitoring. Additionally, sleep and activity can be monitored through a smartphone app (on the Eureka Research Platform). All subjects will receive serial blood draws and saliva sample collections to collect serum, plasma, whole blood, DNA and RNA in order to observe/identify any changes in blood-borne AF markers. Subjects will also undergo serial imaging in the form of an Echo to observe/identify markers and/or changes in cardiovascular structure and functioning. Evaluations will be taken at baseline and once a year for three years from their baseline visit. Additionally, electronic surveys will be administered periodically (eVisits occurring every 3-6 months) using the mobile app to observe any changes in participant reported symptoms.

Any participant who receives an AF ablation as part of clinical care will additionally receive one in-person follow-up three months post-ablation procedure and an electronic survey one month post-ablation procedure to observe changes in symptoms after ablation.

Subjects will be followed for at least 3 years. The total duration of the study is expected to be at least 10 years. It is expected that it will take 3-4 years for subject recruitment and at least 3 years for subject follow-up (3 yearly in-person visits), but anticipate the digital follow-up to go beyond that (at least 10 years of digital follow-up)

Inclusion Criteria:

1. At least 18 years of age or older

2. English speaking

3. Able to consent

4. ANY one of the following criteria:

   1. Patients undergoing ablation for AF.

   2. A history of non-valvular AF or AFL (not due to a reversible cause) documented on ECG or ambulatory monitoring within 1 year of enrollment and not on chronic anti-arrhythmic drugs (AAD).

   3. A history of newly diagnosed persistent AF with documented normal sinus rhythm within 6 months of enrollment and undergoing cardioversion fot AF.

   4. Two or more of the following criteria if no history of AF:

      • Age > 65 years of age
      • A diagnosis of hypertension
      • A diagnosis of diabetes
      • A diagnosis of sleep apnea
      • A BMI ≥ 30
      • Stable HF with preserved or reduced ejection fraction (NYHA Class I, II or III)
      • CKD not requiring dialysis

   5. More than 5% PAC burden on ambulatory ECG monitoring (e.g. Holter, Ziopatch, Lifewatch, etc.)

   6. Patients undergoing EP study or ablation for SVT with no history of AF and not meeting any of the above criteria (a-c).

Exclusion Criteria:

1. Life expectancy < 1 year
2. Reversible causes of AF (e.g., post-operative AF, cardiac surgery, pulmonary embolism, untreated hyperthyroidism)
3. Pregnant at the time of enrollment
4. Unwilling/unable to perform follow-up using digital follow-up
5. CKD requiring dialysis
6. Presence of a condition or abnormality that, in the opinion of the Investigator, would compromise the safety of the patient or the quality of the data
7. Patients undergoing active treatment for cancer or diagnosed with cancer requiring treatment in the last 2 years
8. Severe Valvular Disease (eg. Rheumatic Heart Disease, Severe Mitral Valve Regurgitation, severe tricuspid regurgitation, severe aortic stenosis, or valve replacements)
9. History of organ transplant
10. History of any significant congenital heart defect
11. Existing Pacemakers and ICDs if not undergoing an ablation

Subjects with a diagnosis of AF (i.e. new onset AF, paroxysmal AF, persistent AF, Permanent AF), those undergoing AF ablation or DCCV, those with a PAC greater or equal to 5% PAC burden, those undergoing SVT ablation, subjects with high risk of AF and healthy volunteers at least 18 years of age or older who have been seen at UCSF, who meet the inclusion and exclusion criteria will be eligible for participation in this study.