"My Fitbit saved my life." How an Australian mum's fitness tracker did the unexpected.

A 34-year-old mother of one from Western Australia says she is “lucky” a Fitbit may have saved her life  – after it helped her discover a serious heart condition which can cause heart failure.

Felicity McQueen was given her “middle of the range” Fitbit by partner Darren Nell, 31, for her birthday last year.

“We didn’t want to get the fanciest one, we’re just average people who were trying to get fit,” she told Mamamia.

After a chance glance at the fitness tracker soon after she started wearing it, Felicity noticed her heartbeat was 150 beats per minute. (For adults, a normal resting heart rate ranges between 60 and 100 beats a minute.)

The WA mum was hardly moving - she had been sitting down doing paperwork with her partner.

The pair decided to go the doctor. Felicity was given a 24-hour monitoring ECG test and was referred to a cardiologist and diagnosed with atrial fibrillation.

"The cardiologist could see I had episodes of atrial fibrillation from the test and he said because I am young it’s probably best to do the ablation surgery first - because being on medication forever is not much fun," she said.

"He said he could get some good results from the ablation surgery, but it can be the type of procedure that might need to be done a few times to get it right," she added.

The New Zealand born mother says she's literally heartbroken. She says her condition means her heart is "out of whack". The top of her heart doesn’t work in unison with its bottom half.

People with atrial fibrillation have a higher than normal risk of having a clot form in your heart and if it breaks off it can cause a stroke, according to Health Direct.

The electrical short circuits inside the top chambers of the heart can also cause heart failure.

"In the heart, the sinus node is a natural pacemaker and that sends out electrical impulses which create your heartbeat and with atrial fibrillation you have extra electrical pulses that create an extra beat almost.

"It means that extra tissue in the heart is causing your heart to beat in a very irregular way and that means it’s not working with the bottom of the heart so the blood doesn’t flow properly. So your blood is not getting oxygenated as well as it should be," she said.

Just three weeks ago, the Bunbury mother went into surgery and had an ablation procedure. She's still recovering and sounds slightly out of breath.

"They put a catheter in from an artery in my leg which went right up to my heart and then they tried to find the extra electrical pathways which are causing the misfiring beat. They burn the tissue causing it and that means the heart will go back to the normal sinus rhythm.

"The sinus node will be creating the beat rather than these extra pathways," she said.

The day after surgery, Felicity felt a "huge difference"; her heartbeat was rhythmic and "thumpy".

"I guess I’m not used to it being regular and normal so it took me a little bit to get used to – it was actually quite unsettling but good. It was in a normal rhythm," Felicity said.

But only a day later and she had another episode of atrial fibrillation and her heart was racing again.

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Although Felicity is due for more surgery, she says she's lucky she was diagnosed.

For some 20 years she has suffered health issues and had to get on with life while managing fatigue, dizziness and shortness of breath.

While pregnant, Felicity was admitted into hospital with swelling to her feet and hands and doctors discovered she had tachycardia (a heart rate over 100bpm).

"We noticed it more during pregnancy because I’d been unwell and was being monitored," she said.

But "no one investigated it".  Despite visiting her GP after baby Olivia was born, Felicity was never referred to a cardiologist.

"If it wasn’t for wearing the Fitbit I don’t think we would have bothered getting a second opinion. I’m feeling really lucky."

"The Fitbit saved my life.  If it wasn’t for that it wouldn’t have been investigated at that point in time. So in some ways I can say it has maybe saved my life, we don’t know."

Felicity still wears the activity tracker everyday. She says she'd feel strange without it.

For more about Felicity or to donate to her GoFundMe cause, click here.