2 The technology


2.1 Zio XT (iRhythm Technologies) is a remote cardiac monitoring service used to detect cardiac arrhythmias. It has 3 components:

  • Zio biosensor: a wearable single-lead ambulatory electrocardiogram (ECG)

  • ZEUS: a proprietary, regulated software platform and online portal that stores, analyses and sorts the ECG data to generate a report of the findings

  • Zio technical report: a clinically actionable summary of the recorded ECG data.

    The Zio biosensor is placed on the person's left upper chest. It can be fitted in clinic or sent directly to the person where they can fit it themselves at home. It records a continuous beat-to-beat ECG for up to 14 days. The person can also press a button to register when they feel symptoms (patient-captured events). Each Zio biosensor is intended for single-patient use. After the monitoring period is completed, the wearer removes the biosensor and sends it to the company by Freepost. The ECG recordings are analysed using ZEUS's algorithm, overseen by company-based accredited cardiographic technicians. A technical report including arrhythmia episodes, wear and analysis time, and patient-captured events is sent to the prescribing healthcare professional for final analysis and interpretation. There are no patient identifiers in or on the Zio biosensor, and data cannot be accessed if the Zio biosensor was to be physically intercepted.

Innovative aspects

2.2 Zio XT provides a continuous recording of ambulatory cardiac monitoring for up to 14 days. This is a longer monitoring period than continuous ECG monitors used in NHS standard care, such as a Holter monitor, which can be up to 7 days but is usually for between 24 and 48 hours.

2.3 The wearer can go about their normal daily activities during monitoring, including showering or bathing, because the device is water resistant. Zio XT can be worn under clothing, so may be more discreet than Holter monitors, which are generally worn in a pouch around the waist or neck or carried in a pocket.

2.4 The Zio biosensor has no external leads or wires; this is intended to reduce noise artefacts in the data. Zio XT uses proprietary software to detect arrhythmic events in the ECG data and to create the report that is delivered to the healthcare professional. The intention is to reduce the time needed for NHS staff to analyse the continuous monitoring data.

Intended use

2.5 NICE's guideline on transient loss of consciousness ('blackouts') in over 16s and on managing atrial fibrillation recommend the best ways to detect arrhythmia. The NICE Pathway on heart rhythm conditions describes NICE recommendations on the care pathway for patients. NICE recommends a 12‑lead ECG for the first assessment. If the ECG does not detect arrhythmia, and paroxysmal atrial fibrillation is suspected, ambulatory ECG monitoring is recommended using either Holter monitoring or cardiac event recorders, depending on symptoms and symptom frequency. In people with infrequent blackouts (less than once every 2 weeks), an implantable cardiac monitor may be offered. NICE's diagnostics guidance on implantable cardiac monitors to detect atrial fibrillation after cryptogenic stroke also recommends using an implantable cardiac monitor to detect atrial fibrillation after cryptogenic stroke, if a cardiac arrhythmic cause of stroke is still suspected after ambulatory ECG monitoring.

2.6 Zio XT provides another ambulatory ECG monitor option to current standard care (24‑hour Holter monitoring or cardiac event recorder monitoring) for detecting cardiac arrhythmia in people with palpitations, fainting (syncope) and suspected cardiac arrhythmia. People can wear Zio XT for up to 14 days, which makes it suitable for people who experience symptoms of arrhythmia more than 24 hours apart. Zio XT is prescribed by a healthcare professional, most often a cardiologist or GP, in primary, secondary or tertiary care. It may also be prescribed by a stroke clinician or neurologist.

2.7 Full details on using Zio XT are in the instructions for use.


2.8 During consultation, the company revised the cost of monitoring with Zio XT from £310 to £265 per patient (excluding VAT). This figure includes the cost of the biosensor and the cost of analysing and reporting the data.

For more details, see the website for Zio XT.

  • National Institute for Health and Care Excellence (NICE)