Charge 6 - AFib alert

[Jbondfl]

Has anyone else successfully use d the AFIB feature on this device where it actually notified you of AFIB event? I've had two high events, one last night. I was 170 BPM Resting heart rate and the device never noted it or recognized it. I had a previous event that my heart rate went up to 149 BPM and again, no alert or notification of that event. I don't get it. Any help would be welcome  

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[RiekoC]

Hello @Jbondfl 

This help page explains how Fitbits detects AFib and how the notifications work (<-- click link). 

Basically, Fitbit can only analyze your heart rhythm data for AFib when you’re still. If I remember correctly, the device is monitoring for high heart rate when you're still for at least 10 minutes. 

[LZeeW · Accepted solution]

@Jbondfl   I participated in the Fitbit Heart Study that developed this feature.  Fitbit published the results in the journal Circulation. Your Fitbit must detect an irregular rhythm for a minimum of 30 minutes in order to generate an alert.

[Earther]

I'm pretty sure that Charge 6 reports my heart rate when I'm moving or have just moved, not only when I'm still.

[Earther]

That can't be true, because most aFib incidents don't last 30 minutes. Results of the study that you participated in were published in Circulation on 23 September 2022. I'm responding in August 2025, so surely they've improved that feature by now, and it is different from what you describe, as far as I can tell. 

I've had recent aFib alerts on my relatively new Charge 6. They state the time but not the duration (screenshot follows), so it could be true but it would be quite surprising if so. Notice that I didn't get the notification until 12 hours later, after the incidents were "analyzed." I have an implanted heart monitor (just a monitor, not a pacemaker). I had fluttering that morning but not at that time. So I'm concerned about 2 things:

• Does it differentiate between aFib and tachycardia? I have short instances of tachycardia sometimes, and I'm betting that's what these really were, not aFib. I didn't get this notice until hours later, but I ran an EKG then, and results showed "Normal sinus rhythm."
  
  
• The disparity between the HR irregularity and the Fitbit transmittal of the alert make it not nearly as useful as I had expected and not useful for any true emergency.
  
  

[Earther]

CORRECTION: No option to delete my reply saying "I'm pretty sure that Charge 6 reports my heart rate when I'm moving or have just moved, not only when I'm still." in response to RiekoC's post: 

"Fitbit can only analyze your heart rhythm data for AFib when you’re still. If I remember correctly, the device is monitoring for high heart rate when you're still for at least 10 minutes."

Both are true, but I misunderstood and meant that Fitbit tracks HR data when we're moving, not just still. But it's true that it monitors for aFib only when we're still for at least 10 minutes, plus it doesn't send notifications of any incidents until the data has been analyzed, which can be many hours later.