Smartwatch-Guided “Pill-in-a-Pocket” Anticoagulation for Atrial Fibrillation: The REACT-AF Trial

© 2024 HMP Global. All Rights Reserved.

Any views and opinions expressed are those of the author(s) and/or participants and do not necessarily reflect the views, policy, or position of EP Lab Digest or HMP Global, their employees, and affiliates.

EP LAB DIGEST. 2024;24(3):6.

Dear Readers,

A 72-year-old woman with hypertension is admitted to the hospital with her first episode of atrial fibrillation (AF). She is treated with a beta-blocker and direct oral anticoagulation (DOAC), and spontaneously converts to sinus rhythm. One year later, she is still taking the same medications. During follow-up with her cardiologist, she asks, “I have not had AF again. Why do I need to keep taking blood thinners?” Calculating her CHA₂DS₂-VASc score to be 3, her cardiologist replies that she has a moderate risk of stroke based on her age, sex, and hypertension, and that blood thinners are prescribed based on the risk of stroke rather than how much AF patients have. But is that really what is best for her? 

It might make more sense for patients to take blood thinners only when they have AF rather than all the time. This could greatly reduce exposure to the risk of bleeding in the patient, but is based on the assumption that patients are able to detect a recurrence of AF and that their risk of stroke is based on their AF burden and temporally associated with episodes. Arguments against a temporal association are that patients with AF have strokes because AF is just a marker of an atrial myopathy. However, there is increasing evidence supporting a temporal association.¹ The advent of numerous wearable devices, including AF-sensing smartwatches (AFSWs), that are capable of detecting AF has opened the possibility that DOAC could be prescribed for only a few days after an episode of AF, rather than constantly.

To address this important question related to stroke prevention in patients with AF, Rod Passman from Northwestern and colleagues from around the country have started enrolling patients in the Rhythm Evaluation for AntiCoagulaTion with continuous monitoring of Atrial Fibrillation (REACT-AF).² The $37 million REACT-AF trial, funded by the National Institutes of Health, randomizes patients to remain on their DOAC continuously versus taking it intermittently for only 1 month if a continuous episode of AF greater than 1 hour is detected by their Apple Watch with a customized algorithm designed for the study. The study is a prospective, unblinded, randomized (1:1 allocation), multicenter, investigational clinical trial of subjects aged 22-85 with a history of a low burden of paroxysmal or persistent AF and a CHA₂DS₂-VASc score 1-4. Patients with an AF episode greater than 1 hour or a premature atrial contraction or premature ventricular contraction burden greater than 5% in any 24-hour period on a screening ambulatory monitor are excluded. Participants randomized to the experimental arm will take their DOAC for 30 consecutive days following a qualifying AF episode (ie, greater than 1 hour) detected by their smartwatch. Participants randomized to the standard of care (control) arm will remain on their DOAC. A total of 5350 participants will be enrolled across up to 80 study sites and followed for 5 years. The primary objective of the REACT-AF trial is to assess whether smartwatch-guided, time-delimited DOAC therapy is noninferior to continuous DOAC therapy for a composite endpoint that includes: (1) ischemic stroke; (2) systemic embolism; and (3) all-cause mortality. As of February 2024, the REACT-AF trial has enrolled 300 patients from 42 active sites (personal communication, Rod Passman, MD). 

So, in a few years, when patients with a moderate risk of stroke ask if they need to keep taking blood thinners for an episode of AF that took place years ago, the answer might be only if they have another episode, as long as they wear a device reliably capable of detecting a recurrence. 

Disclosures: Dr Knight has served as a paid consultant to Medtronic and was an investigator in the PULSED AF trial. In addition, he has served as a consultant, speaker, investigator, and/or has received EP fellowship grant support from Abbott, AltaThera, AtriCure, Baylis Medical, Biosense Webster, Biotronik, Boston Scientific, CVRx, Philips, and Sanofi; he has no equity or ownership in any of these companies.

References

1. Singer DE, Ziegler PD, Koehler JL, Sarkar S, Passman RS. Temporal association between episodes of atrial fibrillation and risk of ischemic stroke. JAMA Cardiol. 2021;6(12):1364-1369. doi:10.1001/jamacardio.2021.3702

2. Peigh G, Passman RS. “Pill-in-Pocket” anticoagulation for stroke prevention in atrial fibrillation. J Cardiovasc Electrophysiol. 2023;34(10):2152-2157. doi:10.1111/jce.15866