None of those people were saved by the EKG or O2 features (other than that one person noticed a slow heartbeat while playing with the EKG feature). They are talking about the "fall detection feature, heart rate notifications, exercise tracking and even the ability to make a call from your wrist."
The article includes a story on the watch detecting Atrial fibrillation. Presumably this used the EKG feature, since an EKG is the standard clinical tool for diagnosis of AFib.
