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.