# 2/2  REACT-AF: Rhythm Evaluation for AntiCoagulaTion with Continuous Monitoring of Atrial Fibrillation

> **NIH NIH U24** · JOHNS HOPKINS UNIVERSITY · 2022 · $1,839,921

## Abstract

Project Summary / Abstract
Purpose: The Rhythm Evaluation for AntiCoagulaTion with Continuous Monitoring of Atrial Fibrillation (REACT
AF) clinical trial will compare the efficacy and safety of two treatment strategies for stroke prevention in atrial
fibrillation (AF): the current standard of continuous direct oral anticoagulation (DOAC) versus a novel strategy of
precision, time-delimited DOAC initiated only in response to a ≥ 1-hour AF episode detected by an AF-sensing
smartwatch (AFSW (Apple Watch)).
Rationale: Stroke risk is often temporally related to AF onset and duration, but bleeding risk continues as a
constant risk of anticoagulation exposure even during long AF-free periods when stroke risk may be low. REACT-
AF will evaluate the benefits and risks of withholding anticoagulation during prolonged periods of sinus rhythm
as guided by an AFSW. Compared with continuous DOAC, AFSW-guided, time-delimited DOAC treatment may
reduce bleeding events while maintaining stroke protection. This has potential to improve important major clinical
outcomes and quality of life while reducing health care utilization.
Design: REACT-AF is a multicenter prospective, randomized, open label, blinded endpoint (PROBE design) trial
comparing the current standard of care of continuous DOAC administration versus time-delimited DOAC
treatment guided by an AFSW in patients with a history of paroxysmal or persistent AF and low-to-moderate
stroke risk (CHA2DS2-VASc score 1-4). The study will have an initial explanatory phase I followed by an
explanatory phase II with pragmatic elements.
Primary Aim 1 (Efficacy Objective): To assess whether AFSW-guided, time-delimited DOAC therapy is non-
inferior to continuous DOAC therapy for a composite endpoint that includes: (1) Ischemic Stroke; (2) Systemic
embolism; (3) All-cause mortality.
Hypothesis: Time-delimited DOAC therapy is non-inferior to continuous DOAC therapy for the composite
endpoint of ischemic stroke, systemic embolism, and all-cause mortality.
Primary Aim 2 (Safety Objective): To assess whether AFSW-guided, time-delimited DOAC therapy significantly
reduces major bleeding events compared to continuous DOAC therapy.
Hypothesis: Major bleeding events will be significantly lower in participants randomized to AFSW-guided, time-
delimited DOAC therapy compared with participants receiving continuous DOAC therapy.
Exploratory Aim 1: To compare overall participant satisfaction with anticoagulation management between the
two study arms.
Exploratory Aim 2: To compare estimates of health-related resource utilization in participants randomized to
control versus experimental arms.

## Key facts

- **NIH application ID:** 10509053
- **Project number:** 1U24HL165066-01
- **Recipient organization:** JOHNS HOPKINS UNIVERSITY
- **Principal Investigator:** DANIEL F HANLEY
- **Activity code:** U24 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $1,839,921
- **Award type:** 1
- **Project period:** 2022-08-25 → 2029-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10509053

## Citation

> US National Institutes of Health, RePORTER application 10509053, 2/2  REACT-AF: Rhythm Evaluation for AntiCoagulaTion with Continuous Monitoring of Atrial Fibrillation (1U24HL165066-01). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10509053. Licensed CC0.

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