Researchers are gathering information to see if using an FDA approved implantable device can help with monitoring of your heart arrhythmias.

Inclusion Criteria:

• Cardiac biopsy or technetium pyrophosphate scintigraphy confirmed patients
• Stage I, II, and early and late stage III in numbers as described , irrespective of EF or NYHA functional class
• Patients aged 18 -85, both genders and of all races and ethnicities.
• Patients must be competent to give informed consent.
• Patients must be able to have the Biomonitor 3 implanted.
• Amyloid stage I-III patients with existing implantable cardiac devices such as pacemakers or defibrillators

Exclusion Criteria:

• Significant coronary artery disease > 75% luminal stenosis in at least 1 epicardial vessel (by cardiac catheterization or coronary computed tomography), or history of myocardial infarction or coronary revascularization.
• Congenital heart disease.
• Pregnant patients
• Patients whose heart failure is felt to be secondary to primary valvular disease (>moderate/severe mitral regurgitation), uncorrected thyroid disease, obstructive or hypertrophic cardiomyopathy, pericardial disease or a systemic illness.
• Absolute contraindications to cardiac MRI (such as renal failure with GFR<30%).
• Unwilling or unable to provide informed consent.
• Patients with other life threatening diseases that would likely decrease their life expectancy over the next four years.
• Patients who are post cardiac transplant.
• Difficulty to attend the follow-up schedule due to a history of medical noncompliance, difficulty, or unwillingness to return to the study center for follow up.
• Evidence of ongoing bacteremia or sepsis preventing implantation of a device
• Unwilling or able to have the Biomonitor 3 interrogated

Adverse events were collected for each participant for 6 months, from baseline until device ex-plantation.