Fitbit, which Google is currently seeking to acquire for $2.1 billion, trailed device manufacturer rivals in product development and approval in the heart rhythm tracking arena. But the playing field has leveled off with Monday's announcement the San Francisco-based wearables giant received 510(k) clearance from the FDA and a CE mark in the European Union.

Atrial fibrillation, or irregular or rapid heart rate, causes poor blood flow and can lead to blood clots, stroke, heart failure or other cardiac complications. It affects some 33.5 million people globally, but is notably difficult to detect. Wearables companies have been testing and notching up approvals for their devices as early warning detectors for signs of AFib, bolstered by the industrywide shift to remote monitoring and healthcare in the home. The hope is patients will assume a more proactive role with their health and, informed by data, flag potential symptoms for their doctors.

But any evidence that wearables gets people to change their day-to-day health, fitness and wellness behaviors is spotty. Experts in the field, worried false positives could lead to unnecessary medical interventions, have argued any abnormalities flagged by smartwatches shouldn't be accepted as a diagnosis. And studies have shown limitations around the devices' ability to effectively monitor heart rhythm.

Fitbit conducted a multisite clinical trial in the U.S. to evaluate its algorithm's accuracy in detecting AFib from normal sinus rhythm and generating an EKG trade, or recording of the heart's electrical rhythm, as part of the approval process.

The study showed the algorithm exceeded target performance, detecting 98.7% of AFib cases. It was also 100% accurate in identifying people with normal sinus rhythm, Fitbit said.

The 13-year-old manufacturer also launched a heart rate study in May this year with the goal of validating its photoplethysmography (PPG) technology in finding irregular heart rhythms that could be signs of Afib. PPG monitors miniscule fluctuations in blood volume in the wrist as the heart beats. Fitbit hopes the results of the study, which enrolled more than 400,000 participants in about four months, will bolster its regulatory submissions for its long-term heart rhythm device features.

Fitbit lately has been trying to reposition itself more as a health- and wellness-oriented operator, moving away from its roots as a fitness tracking devicemaker. The $329.95 Sense device is Fitbit's first with an EKG.

The company is also studying whether its devices are effective in detecting early symptoms of COVID-19, as new cases continue to mount in the U.S. largely unchecked. The results of the study launched in May have yet to be published, but a preprint released in August maintains Fitbit sensors flagged almost half of COVID-19 infections one day before participants noticed symptoms.

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