This trial assesses the wear performance of the Zio monitor, a long-term continuous ambulatory patch ECG monitor, in a representative population by evaluating (1) the wear duration (up to 30 days) of the device, (2) the percentage of analyzable electrocardiographic time and (3) safety by reviewing all adverse events.

This is a prospective, multi-center, single-arm study to validate the design of the Zio monitor/Zio MCT device form factor in extended (21-day) wear when utilizing an updated skin prep process.

The trial is conducted in 2 phases. Phase I includes the standard skin preparation process of 40 strokes with an exfoliator in 4 different directions. Phase II incorporates a modified skin preparation process: only 20 strokes with an exfoliator in 2 directions are used. There are 75 participants in each phase.

Performance objectives include the following: (1) Mean wear duration of 21 days and (2) percent analyzable time of 80%.

Safety measures include the proportion of participants that experience clinically significant skin irritation through 30 days of wear, as well as the reporting of all adverse events.

Additional device measures include the following: (1) % signal artifact (defined as the proportion of ECG signal that is artifact over the wear duration, reported for each study device); (2) % device functionality (defined as the proportion of Zio monitors recording a continuous ECG signal through 21 days, and through 30 days) and (3) observational assessment of participant skin types (assessed by dryness levels, hyperhydrosis status, Fitzpatrick Skin Type and chest hair density).

All analyses will be performed on the population of enrolled participants on whom the Zio monitor application was attempted. The age, sex at birth, and application type (i.e., healthcare provider (HCP) designee vs. self-application) of participants will be monitored throughout the enrollment period to ensure representation across key user groups. Performance within subgroups including (but not limited to) sex at birth, age, and application type will be assessed.

Up to 150 participants will be enrolled at 2 US iRhythm locations (San Francisco, CA and Deerfield, IL).

There are 3 on-location visits at Baseline (Visit 1/time of patch application), Day 21 (Visit 4) and Day 30 (Visit 5/following 30 days of patch application). There are 2 telephone/video calls at Day 7 (Visit 2) and Day 14 (Visit 3).

Participants who meet all inclusion criteria and no exclusion criteria will be enrolled.

Inclusion Criteria:

1. Participant must be 18 years or older at time of informed consent.
2. Participant is willing and able to provide informed consent and be able to complete all visits for the study.

Exclusion Criteria:

1. Participant has a known allergy to adhesives.
2. Participant has a current skin infection or injury at location for study device placement.
3. Participant is a member of a vulnerable population.
4. Participant is a current or prior employee of iRhythm.
5. Participant is unable or unwilling to participate or comply with study protocol.
6. The local Investigator deems the participant has a condition that could limit the participant's ability or willingness to participate in the study, or ability to comply with study required procedures and/or follow-up visits.
7. Participant has experienced symptomatic episodes where instance variations in cardiac performance could result in immediate danger to the participant.
8. Participant has an external cardiac defibrillator or may be exposed to high frequency surgical equipment near strong magnetic fields or devices such as MRI during the wear period.
9. Participant has a neuro-stimulator, as it may disrupt the quality of ECG data.
10. Participant does not have the competency to wear the device for the prescribed monitoring period.
11. Participant does not have the ability to consent for themselves (i.e., no LARs).

Individual participant data will not be available to other researchers.