Comparisons between Apple Watch's irregular pulse detection and concurrent electrocardiographic patches indicate that the pulse detection algorithm (showing positive tachograph reading) has a 71
% positive predictive value. Eighty-four percent of cases, participants who received irregular heart rate reports were found in atrial fibrillation at the time of the notification. One third (34 percent) of participants who received irregular pulse notifications and followed by an ECG patch more than a week were found to have atrial fibrillation. Since atrial fibrillation is an intermittent condition, it is not surprising that it can not be noticed in subsequent ECG monitoring
Of over 400,000 participants, the results show that 0.5% have received an irregular heartbeat signal. According to the survey, nearly 57% have sought medical attention from doctors after they have been notified. Apple says that this clock function saves "unnecessary load" on the schedule of the doctor. Apple Watch helps even more users in the future while collaborating with the medical community for further research. "
The Apple Watch Series 4 can perform an ECG, but the feature is not yet available in Canada.