Chris Welch / The Verge:

Apple’s Heart Study, announced with Stanford in Nov. 2017, finds ~0.5% of 400K+ participants using Apple Watch up to Series 3 received irregular pulse alerts  —  Only 0.5 percent of participants received the notifications  —  Apple and the Stanford University School of Medicine each issued …

Apple's Heart Study, announced with Stanford in Nov. 2017, finds ~0.5% of 400K+ participants using Apple Watch up to Series 3 received irregular pulse alerts (Chris Welch/The Verge)
Source: Tech Meme