AF Prevention and the Smartwatch
Can the smartwatch help us tackle one of our most significant challenges?
Atrial Fibrillation (AF) is the most commonly treated cardiac arrhythmia, posing significant challenges to patients and healthcare systems.
As a reminder, I previously provided a general overview of AF, which you can read here.
In this post, we will take a look into AF screening:
Is it possible? If so, how?
How can the smartwatch change how we approach one of humanity's most important problems?
Why screen for AF in the first place?
To answer this question, we need to consider the impact of AF. As mentioned in the previous post on AF, this condition poses major challenges to patients and healthcare systems.
Compared to symptomatic AF, asymptomatic AF has been independently associated with an increased risk of stroke and mortality. [1]
It is essential to take note of the various outcomes related to AF to understand the significance of this medical condition: [1]
Increased hospitalisation (10-40% annual hospitalisation rate)
Impaired quality of life in ≥ 60% of patients
Depression in 16-20% of patients
Cognitive decline/vascular dementia (secondary to clinically apparent or silent strokes or other stroke-independent mechanisms)
Left ventricular dysfunction/heart failure in 20-30% of patients
Stroke: 20-30% of ischaemic strokes and 10% of cryptogenic strokes
Death: 1.5-3.5 fold increase
Given the above, it would make sense to assume that we have a well-established system for screening for AF, right?
Let’s take a look at what we currently do regarding AF screening.
The current state of AF screening
AF screening is NOT widely practised at the moment.
The UK National Screening Committee (UK NSC) reports that screening is not currently recommended for AF (last reviewed in August 2019) due to the following: [2]
There are several types of atrial fibrillation (AF), and it remains unclear whether all types pose the same risk for stroke.
The efficacy of treatment for AF detected through screening is not yet established.
It is unknown whether screening is more advantageous for individuals with AF compared to the current approach for detection and management.
Similarly, the US Preventive Services Task Force (USPSTF) has concluded that there is insufficient evidence to assess the benefits and drawbacks of screening for AF in adults aged 50 and above who do not have any symptoms of AF (last reviewed in January 2022). [3]
As per the European Society of Cardiology (ESC) 2020 Guidelines for Management of Atrial Fibrillation, opportunistic screening for AF is recommended for: [1]
patients with hypertension
patients ≥ 65 years old
and should be considered in patients with obstructive sleep apnoea (OSA).
Problems with AF screening
Although AF has significant consequences for patients and societies, most of our data regarding AF-related outcomes do not come from screening asymptomatic patients.
It's important to note that finding AF in asymptomatic patients comes with increased treatment risks. For instance, using anticoagulation to manage the condition can increase the risk of bleeding, which has to be weighed against the risk of stroke before deciding whether to anticoagulate. It's worth remembering that two essential tools we use to help us decide on anticoagulation are:
the CHA2DS2-VASc score (to assess the thromboembolic risk)
the HAS-BLED score (to assess the bleeding risk and help address modifiable bleeding risk factors)
There are also risks associated with our capacity for follow-up. If we could detect 100% of AF cases early, what could we do for these people with our current resources?
Lastly, what tools do we have to screen for AF? This is where things are changing rapidly and why we might see a significant change in AF screening soon.
The smartwatch as a screening tool
Until recently, pulse taking was the only widely accessible way to check for irregularities in heart rhythm outside of a healthcare facility.
The use of mobile health technologies for detecting AF is rapidly increasing. Currently, over 100,000 mHealth apps and more than 400 wearable activity monitors are available. [1]
Compared to pulse taking alone, new tools like smartwatches with ECG recording capabilities have higher sensitivity and specificity: [1]
Pulse taking
Sensitivity 87-97%
Specificity 70-81%
Smartwatches
Sensitivity 97-99%
Specificity 83-94%
These results indicate that these devices can potentially change the approach to AF screening.
Establishing a definite diagnosis
What happens if screening for AF is positive? Does this mean the patient has AF, and we should start treatment?
Not yet. We need to establish a definite diagnosis first.
Per the ESC guidelines, a definite diagnosis of AF in screen-positive cases is established only after a doctor reviews a single-lead ECG recording of ≥ 30 s
or 12-lead ECG and confirms that it shows AF. [1]
Conclusion
To screen or not to screen?
The USPSTF states that “clinicians should use their clinical judgement regarding whether to screen and how to screen for AF.” [3]
This means that you need to consider and balance the risks associated with the detection and management of asymptomatic AF with the risks of not diagnosing AF early enough (potential AF-related consequences).
Either way, a pivotal part of AF screening is repeatability. Whether it’s pulse taking or using a smartwatch, it’s better to check repeatedly (although no specific frequency for any method is widely accepted) rather than just once.
Your thoughts…
How is AF screening approached in your country? Are there particular protocols or guidelines that you find especially effective or challenging?
In your opinion, are we close to the widespread adoption of AF screening? If so, what do you think is the role of smartwatches or other screening devices in this matter?
Thanks for reading
References
Gerhard Hindricks, Tatjana Potpara, Nikolaos Dagres, Elena Arbelo, Jeroen J Bax, Carina Blomström-Lundqvist, Giuseppe Boriani, Manuel Castella, Gheorghe-Andrei Dan, Polychronis E Dilaveris, Laurent Fauchier, Gerasimos Filippatos, Jonathan M Kalman, Mark La Meir, Deirdre A Lane, Jean-Pierre Lebeau, Maddalena Lettino, Gregory Y H Lip, Fausto J Pinto, G Neil Thomas, Marco Valgimigli, Isabelle C Van Gelder, Bart P Van Putte, Caroline L Watkins, ESC Scientific Document Group , 2020 ESC Guidelines for the diagnosis and management of atrial fibrillation developed in collaboration with the European Association for Cardio-Thoracic Surgery (EACTS): The Task Force for the diagnosis and management of atrial fibrillation of the European Society of Cardiology (ESC) Developed with the special contribution of the European Heart Rhythm Association (EHRA) of the ESC, European Heart Journal, Volume 42, Issue 5, 1 February 2021, Pages 373–498, https://doi.org/10.1093/eurheartj/ehaa612
UK National Screening Committee, Adult screening programme, Atrial fibrillation. https://view-health-screening-recommendations.service.gov.uk/atrial-fibrillation/
US Preventive Services Task Force. (2022). Screening for Atrial Fibrillation. Retrieved from https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/atrial-fibrillation-screening.