A doctor from Philadelphia owes her life to the Apple Watch after it alerted her to a dangerous heart condition.

Erica Harris, 43, was stuck in traffic in November 2021 when she received a warning on her watch that her heart was beating too fast and irregularly – an indication of the potentially dangerous condition of atrial fibrillation.

The emergency room doctor pressed her hands on her chest to increase the pressure on her heart, which brought the organ back to its normal rhythm, she told the Philadelphia Inquirer.

“It lasted almost five minutes, and that’s the point where you’re at risk of having a stroke,” she said. At that point, she had no physical signs that her heart was beating irregularly.

The doctor had been born with a congenital heart defect that required two surgeries, so after receiving the alert, she contacted her cardiologist, who prescribed blood-thinning medication in case she had another attack of atrial fibrillation, the outlet reported.

Although smartwatches do not always provide 100% accurate results and are not recommended without medical analysis, they have alerted some patients to medical events who would otherwise not have known about them.

Erica Harris, 43, was stuck in traffic in November 2021 when she received a warning on her watch that her heart was beating too fast and irregularly – an indication of a potentially dangerous condition of rapid atrial fibrillation

Her watch gave her an urgent warning and she was able to press her hands to her chest to get her heart back into a normal rhythm. Harris, who was born with a heart condition, went to her cardiologist afterward and was prescribed blood thinners to take in case the event happened again.

According to Care Evolution, up to 30 percent of American adults wear smartwatches with health tracking features.

Nora Bursztein, 74, was one of those patients who, like Harris, received an urgent alarm informing her that her heart rate was 48 beats per minute, when it normally ranges between 60 and 70 beats.

“I ignored it and thought maybe it was the clock,” she told the Inquirer.

She received the alert several more times over the course of a few days, and when she tried on her daughter’s watch and noticed a lower heart rate, she wondered if something was wrong.

“The next day I had surgery,” she said. A defibrillator and a pacemaker were inserted.

The American Heart Association recommends that users seek medical attention if they receive an alert from their watch. Patients can undergo an electrocardiogram (ECG) during a doctor’s visit to test the heart rhythm and determine if there is indeed a medical problem.

However, smartwatches can be life-saving tools, identifying trends that patients might otherwise have missed.

An Apple Watch can inform the wearer about high and low heart rates and indicate whether the heart rhythm is abnormal. It documents the data in the app, which can later be presented to a doctor for further evaluation.

However, users should remember that the watch is not a medical device and external circumstances can affect the data collected and make it inaccurate. According to The Inquirer, about 20 percent of the alerts are false.

“We need to be sure we have an accurate diagnosis,” cardiologist Stavros Stavrakis told The Inquirer.

A team of doctors found in November 2022 that the heart rate information collected by smartwatches is about 90 percent accurate when at rest. During activity, that number drops to 70 percent.

However, it is very rare for a smartwatch to issue an urgent alarm: studies have shown that less than one percent of respondents are affected by this.

Only three to five percent of people over 65 receive an irregular heartbeat warning, Stavrakis said.