The preliminary findings of the Apple watch heart study were announced this weekend: see this link. This study, paid for by Apple and run via the Stanford Medical School, found a 0.5% incidence of previously undiagnosed episodic atrial fibrillation via Apple Watch, a finding which was confirmed with patch type cardiac monitoring in 84 per cent of cases. The Apple Watch algorithm was calculated to have a 71% positive predictive value for intermittent atrial fibrillation.
Atrial fibrillation is a known risk factor for stroke from cerebral embolism. The incidence of stroke in intermittent atrial fibrillation can be reduced by 70% with the use of anticoagulation medication. Thus, finding cases of atrial fibrillation in the general population and considering treating them with anti-coagulation may be of significant value.
One issue that has not yet been decided is whether the population of people with an Apple Watch is comparable to the populations studied when warfarin was found superior to aspirin. Those populations were often in higher risk groups for stroke than wearers of the Apple Watch might be. The incidence of occult atrial fibrillation is thought to be "0.5 per 1,000 person-years before age 50 to 9.7 per 1,000 person-years after age 70." Is treatment then indicated in people in whom consumer electronics shows a rare episode of atrial fibrillation? Or will we find that persons with rare episodes of atrial fibrillation are more common than previously known, and that such persons as a whole do not need anticoagulant treatment, when in some future decade most mass produced clothing will be able to monitor vital signs? Time will tell.
No comments:
Post a Comment