Disclaimer: This analysis is not necessarily applicable to everyone suffering from AFib and should only be taken as a single "data point" in what would otherwise be a large scale study.
Hi Community.
During the last two months I have been diagnosed with Atrial Fibrillation. As a 23 year old male with absolutely no medical precedent and no other health issues, my cardiologist was very interested in investigating the root cause for my fibrillation. Due to this, I thought maybe I could pull my HR data from my account to do some graphs and observe if any trends in my HR could be observed.
Graph of HR Confidence Values vs Month:
Values for HR confidence dropped from ~2.1 prior to AFib onset to ~1.2 once Persistent AFib was diagnosed.
Note: The vertical axis is cropped (does not start at 0), which magnifies smaller differences.
Timeline of events:
On the 17th December 2019 I had a mild fever that lasted two days. Following that, I began having heart palpitations every night and randomly throughout the day, where my heart would accelerate up to 140bpm for 3-5 minutes. This is reflected in the confidence values very clearly - a significant drop occurs immediately after the fever. The values do not recover. My cardiologist believes the infection may have not been the root cause of my AFib, but may have accelerated it.
It is worth noting I had an EKG and blood analysis done in January to check for AFib and it came back negative as I wasn't having palpitations at the time of EKG. I see this period now as the beginning of Paroxysmal AFib, but this is obviously not a medical diagnosis as it's retrospective.
Following the fever, confidence values seem to settle around the 1.7 - 1.8 mark, minus a few days where it drops considerably. Those two days I moved back home due to the virus situation. This meant that I was making effort packing and running around and thus had an accelerated heartrate. Faster heart rates seem to be harder to measure which may explain the temporary loss in confidence.
The next significant drop occurs in April. This is not linked to any particular event, but it may be linked to the lack of exercise due to having to quarantine at home. I was no longer moving around at all (<2000 steps a day). At the time I was starting to feel my arrhythmia more often and my heart felt noticeably weaker, with recurring mild pains and an almost imperceptible heartbeat when touching my chest.
Finally, I had a day of heavy exercise in early June (my account says over 9 hours in exercise zone, but those are not very accurate), after which my heart recuperated its rhythm for two days, leading to the rise in confidence at the end of the graph. This is followed by a sharp drop where it is now (back in fibrillation).
I am now scheduled to get a cardioversion and several electrophysiological exams to diagnose the root cause of my Fibrillation.
Conclusions:
- Once AFib becomes Persistent or Permanent - meaning your heart is in fibrillation for the majority of time or all the time - your Fitbit, or any other devices that measure blood volume via photoplethysmogram, will no longer give an accurate reading. I did not compare between the readings from my Charge 3 and an EKG reading but this has been done before in the community. For me, it was better to purchase a different tracker that actually takes a basic EKG, and completely ignore the fitbit reading, to give me peace of mind and allow me to track the evolution of my situation. If you have AFib, you should only rely on an EKG for a pulse reading.
- Perhaps the most useful hypothesis is that HR Confidence values may offer some indication of the early onset of Atrial Fibrillation. Even without a proper EKG. At least in my case, there are some early trends shown on the graph below. Unfortunately Confidence value readings are not noise-free as they accompany each HR reading. They must be averaged over a one-day or seven-day rolling window, which means you can't just "spot" AFib immediately, but might be able to within a month. This may be common sense, specially to the developers who know how the Confidence values are calculated, but I thought I would give some anecdotal evidence to back it up.
I hope that other users who may not have access to an EKG may do the same analysis to maybe get a rough idea of when their heart started malfunctioning. For me, this graph has proved invaluable as it demonstrates that the fever I had in December had something to do with my fibrillation, giving doctors a basic timeline of events that I would otherwise not have.
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Platinum Fitbit Product Experts share support knowledge on the forums and advocate for the betterment of Fitbit products and services. Learn more
Best Answer
Platinum Fitbit Product Experts share support knowledge on the forums and advocate for the betterment of Fitbit products and services. Learn more
Best Answer