MONITORING AF AT HOME
SIMPLE OPTIONS FOR MONITORING AF AT HOME
If you have already been diagnosed with atrial fibrillation (AF) then there may be several benefits to monitoring your rhythm at home. For some patients monitoring may help with early detection of recurrent persistent episodes of AF (especially if symptoms are mild or absent) and can assist with timely treatment of the rhythm episode. For people with intermittent, self-resolving episodes there may be value in documenting the frequency and duration of episodes over time to help inform treatment progress and preferred therapy options.
Monitoring options at home can include simply checking your pulse for 20 to 30 seconds- if the rhythm feels irregular then this may suggest AF. If a digital BP monitor is being routinely used to check blood pressure at home this can also provide important observations about the pulse that can indicate AF. Many BP monitors will alert to an irregular pulse, but a further indication of AF can be a significant increase in resting pulse rate eg from 60bpm to 90bpm or even over 100bpm.
The next level of technology can be the use of an AF detection application (app) on a smartphone or device. These apps require you to place your finger over the camera and an analysis of the blood pulsing through your finger is performed (the scientific technique is called photoplethmysography or PPG for short). This enables observations about the heart rate and pulse waveform- whether it is irregular and suggestive of AF.
Image courtesy of Omron Healthcare
HOME ECG MONITORING
The most accurate way of monitoring the heart rhythm at home is via electrocardiography (ECG for short) which is recording the heart electrical activity through the skin. At least two points of contact across the body are required to record an ECG (called a single lead or single channel ECG). This is the same technology a doctor uses to record ECG at a clinic or in the hospital, although more points of contact with the limbs and chest are recorded in a 12 lead ECG for a more comprehensive assessment of the heart. Doctors can also arrange home ECG monitoring tests eg Holter or ECG patch monitors to continuously record and then analyse the heart rhythm over a more extended period of time.
The first approved ECG device for home use was the Alivecor Kardiamobile (approved by the FDA in USA for medical use). The small device connects via Bluetooth to a smartphone or device and a 30 second recording of the heart rhythm can be performed in the Kardia app by placing a finger from each hand on the 2 metal electrodes of the device. The device is compatible with Android and Apple. Attention needs to be paid to achieving good quality tracings for interpretation. These tracings can then be used for diagnosis of heart rhythm abnormalities by a doctor. Automated analysis can often be provided by the app using ‘algorithms’ to analyse the recording eg if the app detects an irregular rhythm (and there can be different explanations for irregular heart rhythms eg sinus rhythm with frequent ectopic or skipped beats) then it will usually default to a ‘diagnosis’ of possible atrial fibrillation. If the app detects a regular rhythm with a heart rate range between 60 to 100bpm it will allocate a ‘diagnosis’ of normal sinus rhythm. Kardia offers a service for a fee to have individual tracings analysed and reported by a medical professional, otherwise the tracings can be reviewed at an appointment with your doctor.
Image courtesy of AliveCor
WEARABLE SMART WATCHES WITH ECG
Home ECG recording has now been included into a wide range of ‘wearable’ smart watches along with other ‘biosensors’ eg PPG. For an ECG recording a measurement is taken by the smartwatch via one electrode on the back of the wrist and by placing a finger from the opposite hand on the metal watch button or dial. Some smartwatches also use PPG in the background to track heart rate and irregularity of rhythm over a 24 hour period to try to build an ‘AF diary’. As always the quality of the device, performance of the sensors and sophistication of the algorithms will determine how accurate and useful the information collected and displayed will be (and whether the premium paid for this additional technology is a good investment). Currently the medically approved smartwatch ECG devices in Australia include Applewatch, Samsung and Fitbit. A compatible smartphone or device may be required to use the ECG app or to download the information.
Image courtesy of Apple
Image courtesy of Samsung
Image courtesy of Fitbit
CAN A SMARTWATCH BE USED TO DIAGNOSE AF?
ECG must be used for a diagnosis of atrial fibrillation. Description of symptoms of an irregular pulse or observations about an irregular pulse made by techniques such as home BP monitor or PPG sensors can be suggestive but are not diagnostic. Because many people with AF may have intermittent, short episodes when the condition first appears it may be challenging to record the heart rhythm at these times with traditional medical tests. The benefit of being able to record an ECG at home or on the move when the symptoms occur can help to clinch the diagnosis. It is therefore possible (and becoming more frequent) for doctors to diagnose AF from a good quality Kardiamobile or smartwatch ECG tracing.
WHAT ABOUT SMARTWATCHES WITH BP MONITORS?
For the time being the only medically approved and accurate way to measure blood pressure is via an inflatable cuff that externally measures the pressure inside the artery. The measurement is usually taken around the upper arm (or thigh) with some reduction in accuracy for measurements taken at the wrist. Omron is a leading brand in digital BP monitors and they have released a smartwatch version (Omron HeartGuide) which can perform BP measurements via an inflatable cuff technique at the wrist. The device is medically approved by the FDA. Each measurement has to be performed manually - there isn’t currently a function to automatically measure BP at different times during the day or when sleeping. Other smartwatches exist eg Samsung which claim to monitor BP via biosensors (PPG and bio impedance) but for the time being studies show that these technologies are not sufficiently medically accurate. They should not be used for the diagnosis or monitoring of hypertension.
BUYER BEWARE!
Digital health technologies continue to expand at a rapid rate and are changing and improving the interface between doctors and patients. There is improved scope for patients to be involved in the diagnosis and monitoring of their health conditions and to achieve timely and optimal treatment by notifying changes in their condition that they have detected at home. It is vital that the health monitoring technologies are shown to be medically accurate - the effects of inaccurate data can be a waste of time, money, increased stress and detrimental treatment. Home monitoring of specific health conditions such as AF or high blood pressure involves a partnership between your doctor(s), you and reliable technology. Discuss the appropriate home monitoring techniques with your doctor before making an investment.