4 Discussion
To our knowledge, this is the first study to demonstrate the feasibility
and veracity of the BigThumb monitoring device. The primary finding of
this study is that follow-up after AF ablation using BigThumb leads to a
more frequent detection of AF recurrence and more adherence on oral
anticoagulation. Artificial intelligence algorithm improves the accuracy
of ECG diagnosis.
It was reassuring to see abundant devices and applications available in
post-ablation follow-up. ECG and Holter monitoring are the most
frequently applied techniques to detect AF recurrence in previous
studies. However, low-frequency monitoring is not sufficient for
follow-up5-6. Pulse wave monitor devices are also used
in AF detection with unsatisfied accuracy7-8.
Accumulating evidence and meta-analyses have demonstrated that
insertable cardiac monitor (ICM) and cardiac implantable electronic
device (CIED) detect a high rate of AF typically missed during routine
clinical care in patients after ablation9-11. Early
detection of AF is important to define or change proper medical
treatment12. However, implantation of the devices is
invasive and expensive which prevent them from the popularity in
follow-up.
AliveCor is a monitor attached to a WiFi-enabled iPod to obtain ECGs in
ambulatory patients13. It brings contextualized
medical-grade ECG technology to the consumer and will inevitably improve
AF detection compared with current practice14. Halcox
et al conducted a randomized controlled trial of AF screening using
AliveCor to obtain ECGs15. Among the 60440 ECG
tracings, only 1% (600 ECGs) were categorized as AF by the automated
AliveCor algorithm. Of these, only 5% (30 tracings) were confirmed to
be AF. The low positive predictive value of the AliveCor for the
detection of AF was an unexpected observation and made the current
generation of AliveCor devices as a screening tool difficult to
justify16. Similarly, the BigThumb, used for
smartphone-based ECG collection, paralleled the AliveCore in structure
design, but the sensitivity and specificity of the AI algorithm were
94.4% and 98.5%. It has the potential to reduce the manual review. The
use of mobile ECG self‐recording devices allows for earlier detection of
AF recurrence and may empower patients to engage in shared health
decision‐making.
There is emerging evidence that AF recurrence after ablation may be
asymptomatic. Studies have shown that asymptomatic AF may be
increasingly common after ablation and potentially pose a greater
thromboembolic risk than symptomatic AF17-19. In the
present study, we found that 785/3299 (23.8%) of AF detected after
ablation were asymptomatic, that may explain the poor compliance with
anticoagulation after catheter ablation even if patients receive
recommendations of anticoagulation from doctors. The BigThumb may help
to record the episode of asymptomatic AF according to random monitoring
which may lead to subsequent adherence on anticoagulation.
The BigThumb is an effective and affordable public ECG monitoring
device. This is critical for successful incorporation of
consumer-generated biometrics into clinical practice. However, it has
limitations. ECGs tracings in this clinical trial provide an insight
into the real-world limitations of the technology. Because of random and
haphazard collection of bECGs, the accuracy of AF detection with the
BigThumb highly depends on the compliance of participants. As we found
in this study, the BigThumb was used frequently in the first 3-month
follow-up than after 3-month. Patients should be reminded to
persistently utilize the device. We also found in this study that the
frequency of monitoring in the night was significantly lower than the
daytime as expected. Some asymptomatic episodes in the night may be
missed. Moreover, despite the best intentions of a health-conscious and
motivated individual, the potential for heightened concern with abnormal
or equivocal readings remains.
In conclusion, we found that follow-up after AF ablation using BigThumb
with artificial intelligence algorithm is more effective than
traditional strategies. It is conceivable that in the near future, most
patients after ablation will be continuously and indefinitely monitored.