When Apple announced AFib History as part of watchOS 9, it sounded like a kind of useful feature to have, but not really relevant to most people. But stated quietly within the announcement was something that I think will be absolutely huge, as the Watch gains the ability to detect more health conditions.
The Watch is going to play a massive role in helping you and your medical professionals to identify the role that lifestyle factors may have on your health …
Background
Atrial fibrillation (AFib) detection came to the Apple Watch with the launch of the Series 4. Apple obtained FDA approval for the feature after a study showing that it was 98% accurate.
Since then, there have been a great many reports in which the AFib detection feature was credited with saving lives. Here are just a few examples:
- Apple Watch user discovers A-fib heart issue with new ECG app, ‘this probably saved you,’ says doctor
- Apple Watch skeptic discovers Afib days after ECG app reaches Europe
- Apple Watch customer identifies A-fib heart condition after dismissing symptoms as ‘holiday anxiety’
- Apple Watch credited with alerting Seattle man his A-fib had returned, potentially preventing stroke
- Reddit user says Apple Watch saved his life helping detect supraventricular tachycardia
- Tim Cook shares story of user who discovered A-fib and other health issues with Apple Watch
“AFib burden”
When doctors assess AFib, it’s not just the fact that it occurred that matters: It’s also important to understand how much time a patient’s heart spends in an AFib state, because this can significantly impact the level of health risk. The percentage of time someone spends in AFib is known as “AFib burden.”
Over the last decade or so the term “burden” has become frequently encountered in manuscripts discussing atrial fibrillation (AF). Electrophysiologists have used it to generally mean the percentage of time that a patient is in AF – calculated from the total time in AF divided by the total monitored time.
Conceptually, this burden may then be linked to some clinical outcome and/or therapeutic decision. For example, the TRENDS study examined whether there is a critical level of AT/AF burden that increases the risk of thromboembolic events independent of other known risk factors.
The investigators found that the risk of thromboembolism doubled if AT/AF burden was ≥ 5.5 hours on any given day during the prior 30 days.
Normally, AFib burden can only be measured during the (usually short) time that a patient is monitored in hospital.
AFib History
This is why the AFib History feature introduced in watchOS9 is so important: It can measure AFib burden over an extended period of time. Here’s how Apple describes it:
Research suggests that the amount of time spent in AFib may impact a person’s symptoms, overall quality of life, and risk of complications. Previously, there has not been an easy way to track the frequency of AFib over an extended period of time, or to manage lifestyle factors that may influence one’s condition. According to the American Heart Association, addressing modifiable lifestyle factors may decrease the amount of time spent in AFib.
With watchOS 9, users who are diagnosed with AFib can turn on the FDA-cleared AFib History feature and access important information, including an estimate of how frequently a user’s heart rhythm shows signs of AFib,
Correlating health conditions with lifestyle factors
But AFib History goes beyond just passive measurement of the time spent in AFib: It also correlates this with other health and lifestyle data. Again, Apple:
According to the American Heart Association, addressing modifiable lifestyle factors may decrease the amount of time spent in AFib.
With watchOS 9, users who are diagnosed with AFib can turn on the FDA-cleared AFib History feature and access important information, including an estimate of how frequently a user’s heart rhythm shows signs of AFib, providing deeper insights into their condition. Users will also receive weekly notifications to understand frequency and view a detailed history in the Health app, including lifestyle factors that may influence AFib, like sleep, alcohol consumption, and exercise.
Users can download a PDF with a detailed history of their AFib and lifestyle factors, which can easily be shared with doctors and care providers for more informed conversations.
In other words, the Apple Watch can now provide doctors with the data to assess whether there is any correlation between AFib burden and lifestyle factors, like how much sleep you got the night before, and how much exercise you are getting. While correlation does not always imply causation, this type of data can be massively useful in assessing risk factors.
Type 2 diabetes may be next
Right now, this ability to draw connections between medical conditions and lifestyle factors is limited to AFib. But as the Apple Watch gains the ability to detect more conditions, it’s a capability that can revolutionize healthcare.
One obvious example is Type 2 diabetes. There have been numerous reports that Apple is working on adding non-invasive blood sugar monitoring into future Apple Watch models, with a Nature piece last year describing one potential technology the company may use to achieve this.
This paper reports a highly sensitive, non-invasive sensor for real-time glucose monitoring from interstitial fluid. The structure is comprised of a chip-less tag sensor which may be taped over the patient’s skin and a reader, that can be embedded in a smartwatch.
The tag sensor is energized through the established electromagnetic coupling between the tag and the reader and its frequency response is reflected on the spectrum of the reader in the same manner. The tag sensor consumes zero power as there is no requirement for any active readout or communication circuitry on the tag side.
Couple this to things like food diary apps and metabolic testing, all feeding into the Apple Health app, and it’s not hard to see just how transformative a role can be played in a whole range of medical conditions.
With many more conditions likely later
The Apple Watch started with a simple heart-rate sensor, and just that was enough to later lead to FDA-approved ECGs, AFib detection, and – in the Apple Watch Series 6 – oxygen saturation.
A study conducted last year found that this was a reliable form of measurement for patients with lung diseases.
A new study published on Scientific Report, an online multidisciplinary, open-access journal from the publishers of Nature, shows that the Apple Watch Series 6 “is a reliable way to obtain heart rate and oxygen saturation (SpO2) in patients with lung diseases under controlled conditions.”
The study from the University of São Paulo, one of Brazil’s more prestigious education institutions and was conducted with 100 patients with chronic obstructive pulmonary disease and interstitial lung disease from an outpatient pneumology clinic. It collected SpO2 and heart rate data with Apple Watch Series 6 and compared them to two commercial pulse oximeters.
The study observed “strong positive correlations between the Apple Watch device and commercial oximeters. It notes that “there was no statistical difference in the evaluation of skin color, wrist circumference, presence of wrist hair, and enamel nail for SpO2 and hear rate measurements in Apple Watch or commercial oximeter devices.”
Imagine being able to correlate O2 sats with things like the number of steps walked, flights of stairs walked, sleep quantity and quality, and so on.
All of this is possible from just a single sensor. When we envisage more sensors being added to future models, the potential of the Apple Watch to assist with a whole range of medical conditions is just enormous!
What may have sounded like one of the least-exciting Apple Watch features will in time, I think, become one of the most exciting and life-changing ones.
Photo: National Cancer Institute/Unsplash
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