Inclusion Criteria:

• Participants must meet the following criteria to be enrolled in the trial:
• * Participants with atrial fibrillation aged 18 to 79 years old, or
• * Participants aged 40 to 79 years old, at moderate or high risk for CVD as defined by the 10-year risk Atherosclerotic Cardiovascular Disease (ASCVD), a validated risk calculation tool.
• * Participants who have access to internet/e-mail in their homes.
• * Participants who have access to a compatible Android mobile device or compatible iOS mobile device (iPhone 4S or newer, iPad 3 or newer).
• * Participants who are able and willing to return to the study clinic one-year following their baseline CMR for a follow-up appointment and 12-month CMR.
• * Participants who are able to read, understand, and sign the consent form.

Exclusion Criteria:

• Participants will be excluded from enrollment if any of the following criteria are present:
• * Any health-related gadolinium/MRI contraindications (e.g. allergy to gadolinium, pacemakers, Implantable Cardioverter Defibrillators (ICD's), other devices/implants contraindicated for use of MRI, etc.).
• * Participants weighing \>300 lbs. (MRI quality decreases as BMI increases).
• * Participants with renal insufficiency (Glomerular Filtration Rate (GFR) \<30 mL per minute per 1.73 m2) or acute/severe renal dysfunction/disease.
• * Women who are pregnant at the time of enrollment/consent. (Should a participant become pregnant during the course of the study, no CMR will be performed until 10 days, postpartum).
• * Participants who do not have access to the internet/e-mail.
• * Participants who do not have a compatible Android mobile device or compatible iOS mobile device (iPhone 4S or newer, iPad 3 or newer).
• * Participants with cognitive impairments affecting their ability to be compliant with wearing and maintaining wearable devices.
• * Participants who are unable or unwilling to return to the study clinic one-year post baseline for their follow-up appointment and CMR.
• * Participants with cognitive impairments who are unable to give informed consent.