The goal of this study is to compare the heart signals that are received by a new heart monitoring device called the HeartWatch to heart signals that are recorded by existing monitors used in cardiology clinics today. The main question[s] it aims to answer are:

1. Does the HeartWatch recording allow characterization of tagged and abnormal arrhythmia events that are equivalent to the existing Event Recorder and Holter devices?
2. Does the HeartWatch recording allow for detection of QRS complexes that are equivalent to the predicate Holter lead I reference signal? Participants who have been recommended to receive a heart monitor for heart rhythm assessment will asked to wear the HeartWatch armband monitor at the same time as the standard heart monitor. They will be asked to flag symptoms (if they occur) on either the HeartWatch or on the Helpwear Smartphone. When their monitoring session for the standard heart monitor is complete, then the monitoring session for the HeartWatch armband is also complete.

Two general types of consumer products are used to monitor patients with or at risk of heart rhythm disorders. Most estimate heart rhythm using blood flow (photoplethysmography) alone or in combination with activity sensors (accelerometer). These methods are not reliable in detecting heart rhythm abnormalities. Other methods record an ECG when the patient has symptoms. These devices are useful, but require the wearer to recognize their symptoms, attach the device and rest quietly to obtain an ECG recording of reasonable quality. The user then needs to send that information to a healthcare provider to verify. Hence, these consumer-based technologies are far from ideal. However, the diagnostic accuracy of single-lead ECG via wearable medical devices is excellent and, likely superior to a family physician's interpretation of a 12-lead ECG.3 High-quality ECG data from wearable devices that can unequivocally document AF can expedite its detection, allowing prompt diagnosis and appropriate prescription of antithrombotic and other therapies.

The HeartWatch arm band is designed to provide non-invasive, continuous single lead ECG data, irrespective of activity, the environment, and other factors. It continuously records ECG data for subsequent, offline analysis. The HeartWatch allows the user to note (flag) any symptoms they experience (e.g., palpitations, light-headedness, fainting, etc…) to allow for symptom-rhythm correlation and subsequent review by a physician. The HeartWatch displays all the elements of an ECG signal (i.e., PQRST) to facilitate diagnoses by physicians and is comparable to lead I of a traditional ECG system.

The HeartWatch is indicated for the extended diagnostic evaluation of patients with symptomatic and transient symptoms such as light-headedness, syncope and palpitations, as well as patients at risk for arrhythmias, but without significant symptoms.

The primary purpose of the study is to compare the interpretability of all tagged and all non-normal clinically significant arrhythmia events and the detection of QRS complexes by the HeartWatch, an upper armbased, ambulatory, single lead ECG collection tool, vs. conventional Event Recorder or Holter monitor reference device.

Inclusion Criteria:

• At least 22 years of age at time of consent
• Clinically indicated for an Event Recorder or Holter
• Able to follow the protocol
• Provision of written-informed consent
• No functional implantable pacemaker or defibrillator
• Left bicep circumference > 22 cm and < 45 cm

Exclusion Criteria:

• Known allergy to any component of the Event Recorder
• Known allergy to any component of the Holter monitor
• Known allergy to any component of the HeartWatch
• Dextrocardia
• Implanted functional Pacemaker of Defibrillator
• Left bicep circumference < 22 cm
• Left bicep circumference > 45 cm

Consecutive patients referred for extended ambulatory ECG monitoring will be approached for participation. A total of 150 subjects will be enrolled into the two parallel studies, 50 subjects in the HeartWatch vs Event recorder and 100 subjects in HeartWatch vs Holter monitor.