Tachycardia: Charge 3 in pocket recording heart rate - could a high reading be false?

[Mrerytr]

I work on a treadmill desk and routinely take off my Fitbit and put it my pocket to accurately count steps.  I have felt some fluttering in my chest at night and am now enrolled in the a-fib study through Fitbit.  I haven't gotten my EKG patch yet, but will be doing an in office EKG in two days and then have a consult with a cardiologist.  

My questions:

- When worn correctly - two fingers above wrist bone and tight - how accurate is the Fitbit Charge 3?

- It only reports data every five minutes, not continuously, correct, even though it measures continuously

- When in my pocket, there are times it has shown heart rates of 180.  I'm usually wearing pants where the pocket lies close to the skin.  Is it possible for a false reading to be so high?

[Tbwalker81]

Spoiler

Ok I keep trying to answer you but someone keeps reporting it as spam. So I'm sorry

[Tbwalker81]

This is a little long, I’m sorry.
I have a Versa and it used to sync non stop but now it does every so often or if I manually sync. I read somewhere on here that the continuous sync was removed to save the battery or something. I tried to find the article but gave up lol. The study is heart rhythm that may suggest atrial fibrillation which is actually one of the types of S V T so kind of odd I've been in the study for 86 days and never received a notification and I have "attacks" multiple times a week.
There are three major types of S V T including: Atrial fibrillation. Paroxysmal supraventricular tachycardia (P S V T) Atrial Flutter and Atrial Tachycardia.
I have a type of S V T (Paroxysmal Supraventricular tachycardia) and now we believe I have V-Tach (Ventricular tachycardia more rare, appointment in Oct). So I am constantly syncing my device plus I have an implant as well that records. I am 38 and been dealing with heart issues since I was 15, lost count how many times I had to wear 30 day monitors, how many scans, etc etc, had an ablation in 08.
I will say when I go to the dr and they check my vitals, I immediately check my versa and they usually match. So in my opinion mine seems to be accurate.
And for the pants question I honestly have no answer, I’m sorry.
Its good you made an appointment most people would not. I hope it all goes good at the doctor.

[Decoherence]

I've not compared it with a "proper" monitor so hesitate to give a definite answer, but when worn correctly it's been consistent with manual measurements or those from my blood pressure monitor, and consistent between different charge 3's (i.e. I've at different times worn 3 different devices and there hasn't been a shift in the readings). So while I don't guarantee it to be accurate to a few bpm, it's reasonably reliable in my experience. 

I wouldn't trust any reading when it is in the pocket to mean anything at all. It will be moving around in the pocket, relative to skin and to the fabric of the pocket, all of which would interfere with the readings. I would personally expect any HR measurement in those conditions to be worthless. Try keeping it on your wrist and see whether you still see such high readings (I'm a big fan of empirical testing rather than relying on theories or specifications).

[LZeeW]

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@Mrerytr wrote:

I work on a treadmill desk and routinely take off my Fitbit and put it my pocket to accurately count steps.  I have felt some fluttering in my chest at night and am now enrolled in the a-fib study through Fitbit.  I haven't gotten my EKG patch yet, but will be doing an in office EKG in two days and then have a consult with a cardiologist.  

My questions:

- When worn correctly - two fingers above wrist bone and tight - how accurate is the Fitbit Charge 3?

- It only reports data every five minutes, not continuously, correct, even though it measures continuously

- When in my pocket, there are times it has shown heart rates of 180.  I'm usually wearing pants where the pocket lies close to the skin.  Is it possible for a false reading to be so high?

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Question 1 -- I can't say for certain how accurate the heart rate is on any Fitbit device.  Fitbit doesn't publish that data.

Question 2 -- It is true that the heart rate graph shown in the Heart Rate tile shows a number that is an average over five minutes.  A heart rate graph in the exercise details of an exercise has an average over one minute.  If you look at exercise details in the web browser view, you can see even more heart rate detail.  Again, Fitbit doesn't publish the data.

Question 3 -- Your Fitbit in your pocket can definitely give you a false high reading.  Normally, the green LED light turns off when you take your Fitbit off.  It wouldn't surprise me that the light comes back on in your pocket, especially if it is close to your skin.  The fabric will make the "pulse" gibberish.

The heart rate sensor is looking for pulsations in tiny blood vessels just below the skin.  It can sense your pulse from many places on your skin.  Many people can't wear anything below the elbow at work.  They wear their Fitbits on their ankles, an inch or two above the ankle bone on the inside of the leg.  I always try stuff like this to see the results.  I get steps and heart rate with my Fitbit in a sock above my ankle.  Try your ankle at your treadmill desk.

[Mrerytr]

I have gotten my ePatch results and in the summary the highest recorded heart rate was 152 during a time when I was not running - and during that week Fitbit Charge 3 routinely showed readings of 175 or 180 when I ran.  Obviously my Charge 3 is inaccurate to the point of not being useful in regards to my heart rate.  I am wondering if it's just wrong when I run or wrong all the time. 

The study showed SVT not aFib, but my real-live cardiologist is not convinced.  She is having someone look at the readings from the ePatch.  

I have decided not to worry about the readings in my pocket.