The Zio Service (iRhythm Technologies) is designed to detect cardiac arrhythmias and is comprised of the Zio Patch, an adhesive patch with a 1‑lead ambulatory electrocardiogram (ECG), and the Zio Report, a summary of the recorded data that have been analysed.
As cardiac monitoring gets more sophisticated by incorporating algorithms trained on vast amounts of relevant data, companies that bring such products to market are taking care to ensure not only the overall accuracy of the models, but also their ability to detect rare or infrequent arrhythmias. IRhythm Technologies (Nasdaq: IRTC), a California-based digital health care company, has led the ambulatory.
Wearable Patch Holter Monitoring Traditional 24 hour Holter monitoring has evolved substantially in recent years due to the advent of a wearable 3-14 day long term continuous monitoring or long term Holter monitoring patch. Much of the clinical evidence has concluded that there is substantial clinical value in detecting abnormal cardiac arrhythmias with 3-14 times.
The Zio Patch is a lightweight water-resistant ECG monitor that has no external leads or wires. The patch is stuck on the person's left upper chest and can record a continuous beat-to-beat ECG for up to 14 days. Each Zio Patch is intended for single-patient use.
The new ZIO® XT Patch is a continuously recording, wire-free heart monitor that can be worn for up to 14 days, provides high diagnostic yield, prolonged monitoring, high compliance and excellent data quality. A selection of contemporary wireless mobile cardiac monitoring devices.Two leading AECG adhesive patch devices on the medical device market today are (A) second-generation ZIO ® XT Patch by iRhythm Technologies, Inc. And (B) SEEQ™ MCT patch device by Medtronic, Inc. (cellular transmitter not shown).
Wearers can carry on with their usual daily activities during monitoring. When they feel a symptom, the wearer can press a trigger button on the device that highlights the recording 45 seconds before and after the button was pressed. The wearer is also asked to keep a paper-based log in which they write down any symptomatic events that happen during the 14‑day monitoring period, as well as information on what they were doing and the conditions at the time. This allows for a symptom-rhythm correlation to be included in the final report.
After the monitoring period, the wearer removes the Zio Patch and sends it to the company by Freepost through the Royal Mail. The recordings are analysed by the company, using proprietary machine-learned algorithms (Zio ECG Utilization Service System [ZEUS System]), and a report is produced. The report describes all cardiac arrhythmia events over the total wear time and the analysis by the ZEUS system, and it is reviewed by a certified cardiac technician. This Zio Report is sent electronically to the ordering clinician through iRhythm's secure web-based portal. The full ECG data can be sent to the clinician on request. Patient data are otherwise only used by the company in a de‑identified form for quality reporting and system improvements.
Parts of the analysis are done in the UK and the US. The manufacturer states that transmission, processing and storage of all data complies with relevant EU and UK legislation. There are no patient identifiers in or on the Zio Patch and data cannot be accessed if the Zio Patch were to be physically intercepted. iRhythm uses security measures to prevent inappropriate access to or manipulation of the data.
Innovations
The Zio Service provides a continuous recording of ambulatory cardiac monitoring for up to 14 days. The wearer can go about their normal daily activities during monitoring, including showering or bathing because the device is water resistant.
The Zio Service can be used for a longer monitoring period than a standard Holter monitor, which can be up to 7 days but usually for 24 to 48 hours. The Zio Patch has no external leads or wires and this is intended to reduce noise artefacts in the data. It 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.
The Zio Service uses machine-learned analytics in the form of proprietary software to create the report that is delivered to the clinician. This is intended to reduce the time needed for NHS staff to analyse the continuous monitoring data.
Current NHS pathway
The current methods of arrhythmia detection (NHS Choices) are:
12‑lead ECG
24- to 48‑hour or 7‑day continuous ambulatory monitoring, including using Holter monitors
long-term continuous monitoring for up to 30 days
external loop recorders
insertable loop recorders, which can record events for up to 3 years for arrhythmias that occur sometimes months apart.
The Holter monitor is the method most commonly used in the NHS for detecting atrial fibrillation. Holter monitors continuously record the heart rhythm using several electrode patches, which are stuck on the user's chest. These electrodes detect and record electrical signals produced by each heartbeat, and are connected by wires to a portable recording machine. The user can press a button on the front of the recording machine at specific times, such as when having symptoms, going to bed or taking medication. These points can then be easily found in the continuous monitoring data. Holter monitoring is used for 24 to 48 hours for people who have regular symptoms, or can be used for up to 7 days for people with symptoms that happen less often, such as if they only have arrhythmia every 3 to 4 days. Results are analysed by the user's clinician.
The NICE guidelines on managing atrial fibrillation and transient loss of consciousness ('blackouts') in over 16s recommend a 12‑lead ECG for the first assessment. If further assessment of possible cardiac arrhythmia is needed, ambulatory ECG monitoring is recommended for 24 or 48 hours. The choice of monitor depends on symptoms and symptom frequency and includes Holter monitoring and external or implantable event recorders.
If the first 24- to 48‑hour Holter monitor test does not give a clear diagnosis, people are referred for further investigations. This can include event recording for up to 7 days or admission to hospital for more invasive options, such as fitting an implantable loop recorder.
Estimates of the diagnostic yield for 24‑hour Holter monitoring vary. Barbeito–Caamano et al. (2016) reported that syncope was only diagnosed in 4% of people in a cohort monitored for 24 hours. De Asmundis et al. (2014) reported that Holter monitoring led to a diagnosis of any arrhythmia in 1.8% of people monitored for 24 hours, whereas Kinlay et al. (1996) reported a diagnosis rate of 35% after 48‑hour Holter monitoring.
The Zio Service would be used for monitoring over 14 days as well as, or instead of, 24- to 48‑hour and 7‑day Holter monitoring or event recording.
NICE is aware of the following CE‑marked devices that appear to fulfil a similar function to Zio Service:
Bardy 7‑day patch (Cardiologic)
SEEQ MCT monitor (Medtronic)
Population, setting and intended user
The Zio Service would be used in a home setting for people with suspected cardiac arrhythmias. The device can be used for people with suspected arrhythmias and unexplained loss of consciousness. The Zio Service would be used instead of Holter monitoring or event recording when continuous monitoring needs to be extended for up to 14 days.
A clinician would prescribe monitoring with the Zio Service, most likely a cardiologist in secondary care or possibly a GP in primary care. The Zio Patch is intended to be applied to the person by the clinician, or by a cardiac physiologist or healthcare support worker in hospital, or a nurse or healthcare support worker in primary care. Occasionally, it may be applied by the person themselves if the clinician thinks that this is appropriate. After the monitoring period, the person sends the Zio Patch by Freepost through the Royal Mail to iRhythm for data analysis and production of the report.
The manufacturer states that minimal training is needed to apply and use the Zio Patch and that full instructions are provided in the user manual. The chest area may sometimes need to be shaved before applying the device. iRhythm states that the clinician will not need additional training to interpret the Zio Report, because it is clear and complete.
Very occasionally, such as with paroxysmal atrial fibrillation, monitoring for more than 14 days may be needed because events are very intermittent. In this situation 2 patches would be worn in succession.
Costs
The manufacturer has given an example list price of £800 per unit for the Zio Service. In practice, prices will vary depending on the procurement and volume arrangements for each hospital. This single price includes the cost of the Zio Patch, the data analysis, and the clinical report for one 14‑day monitoring period for a single patient. A specialist commentator provided the following costs (excluding equipment costs) for 24‑hour Holter monitoring, per patient:
monitoring and interpretation of results:
£95.42 without overheads (defined as staff, heating and computer use)
£118.60 with overheads
monitoring and no interpretation of results:
An example of a reusable Holter monitor is the Spacelabs LifeCard CF Holter recorder, which has a list price of £1,632.14 (NHS Supply Chain).
Resource consequences
The Zio Service is currently available in 6 NHS trusts.
The purchase price of the Zio Service may be lower than that of a Holter monitor, but the cost of 24‑hour Holter monitoring per patient would be lower. Cost savings could be generated if using the Zio Service reduced the need for repeated or prolonged Holter or event monitoring. The Zio Service offers 14‑day monitoring, which may improve the detection of infrequent arrhythmias compared with 24- to 48‑hour or 7‑day Holter monitoring. This could save any costs that could be avoided by having a correct diagnosis, including repeat hospital inpatient and outpatient admissions related to complications such as syncope, chest pain, stroke or transient ischaemic attack.
The costs of applying the Zio Patch to the patient are minimal. It is simple to use and can be removed without medical supervision. People having Holter monitoring must visit the cardiologist to return the monitor after the recording period, whereas the Zio Service is returned to iRhythm by post, which may be more convenient for people.
Wearable Devices for Ambulatory Cardiac Monitoring: JACC State-of-the-Art Review. J Am Coll Cardiol 2020;75:1582-1592.
The following are key points to remember from this state-of-the-art review about wearable devices for ambulatory cardiac monitoring:
Remote health care, virtual care, mobile health, and e-health refer to activities made possible due to ambulatory devices for continuous and remote monitoring. There are three essential components in such systems: 1) a wearable sensor, 2) a network and communication interface, and 3) remote cloud analytics managing large amounts of data.
Wearable ambulatory sensors often incorporate an accelerometer, which detects movements, and other modalities such as a ballistocardiogram, which allows for sensing the heart rate and blood ejection.
The Zio patch provides a single-lead electrocardiogram (ECG) and is used for continuous monitoring of cardiac rhythm. Due to the extended monitoring time of up to 14 days, the Zio device has a higher diagnostic yield than the Holter monitor. Like Holter, the data from Zio monitor are analyzed offline after the completion of monitoring. NUVANT Mobile Cardiac Telemetry (MCT) provides real-time wireless arrhythmia monitoring and analysis.
Scanadu is based on photoplethysmography, held between the fingers while directed at the head, and provides heart rate, blood pressure, temperature, respiratory rate, and oxygen saturation. Apple’s watch has sensitivity and specificity of 87% and 97% for the identification of silent atrial fibrillation. Another product, cvrPhone, is capable of identifying ischemic and apneic events using 12-lead ECG only.
A smartphone-based cuffless blood pressure monitoring device detects variable-amplitude of blood volume variations on the finger to produce a blood pressure measurement with a high precision. A number of devices provide estimates of cardiorespiratory fitness and even psychological stress.
Since 2016 there has already been widespread adoption of smartphone technology with nearly two-thirds of the US population owning a smartphone. According to surveys, Americans, especially the young, are open to health care options enabled through, and up to 78% of respondents appear willing to provide their health data from wearable devices to their physicians. The adoption of mobile health and telemonitoring is impeded by issues related to reimbursement and insurance policies. Some studies suggest health care savings secondary to the reduction in readmission rates.
A major vulnerability of the wearable devices is their susceptibility to motion artifacts, and changes in temperature, hair, skin color, and tattoos. Multimodal signals tend to reduce uncertainty.
Privacy, security, and data ownership are some issues that still need further consideration and scrutiny. General Data Protection Regulation, enacted by the European Union, aims to assure customer consent for the data collection, analysis, and utilization.
Clinical Topics:Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Prevention, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Stress