When Apple announced its latest Series 4 Watchwith electrocardiogram features, my mom took a sigh of relief, and then proceeded to set a reminder to order one for my dad.

That because we found out last year, by chance, that he has atrial fibrillation.

Atrial fibrillation is an irregular heartbeat, often times rapid heart rate that can increase your risk of stroke, heart failure and other heart-related issues. The ECG feature, which monitors your heart rhythm and can detect AFib,*went live just two days ago.

Already, at least one person has benefited from it. Yesterday, a person on Reddit shared how their Apple Watch notified them of an abnormal heart rate.

From there, they ran the ECG app and found out it was AFib.

They went to urgent care and saw a doctor whothey say said, &You should buy Apple stock.

This probably saved you.

I read about this last night and thought we would see an upswing this week.

I didn&t expect it first thing this morning.& The patient says they proceeded to go to a cardiologist the next day, who did an exam and confirmed the AFib diagnosis. &I&m scheduled to go back in a week for some additional tests to start looking at the cause… blood, thyroid, etc…,& they wrote.

&He also scheduled me with a partner who specializes more in the electrical side of things to have it looked from that angle as well.& As one of the first more widely-owned ECG monitors, this could make a huge difference in the number of people who have at least some transparency into their heart health.

But to be clear, once you enable the new feature, the watch is still not constantly looking for AFib.

When the heart rhythm monitor detects something is off — a skipped or rapid heartbeat, for example — it will send a notification to your wrist. That when you open up the ECG app, rest your arm on your lap or table, and then hold your finger to the crown for 30 seconds.

From there, the watch will tell you if there are signs of atrial fibrillation. If you want to learn more about the features, check out my colleague Brian Heater piece below. The Apple Watch ECG feature goes live today