Heart Rhythm Monitoring Practices, Detection of Atrial Fibrillation, and Effect of Anticoagulation in the ARCADIA Trial

Abstract

Background: The ARCADIA (Atrial Cardiopathy and Antithrombotic Drugs in Prevention After Cryptogenic Stroke) trial found no benefit of anticoagulation for preventing recurrent stroke in patients with atrial cardiopathy. Data on AF monitoring across trial sites may provide context for the findings and knowledge about the current standard of care for poststroke monitoring.

Methods: At study visits, sites reported any preceding use of prolonged heart rhythm monitoring, classified as either external ambulatory monitors or implantable loop recorders. We used relative risk regression, least absolute shrinkage and selection operator (LASSO) regression, and survival analysis to explore patient characteristics associated with monitoring, the association between monitoring and AF detection, and the interaction between monitoring and study treatment effect on recurrent stroke.

Results: Of 1633 patients with monitoring data, 957 (58.6%) underwent prolonged monitoring: 567 (34.7%) external ambulatory monitor, 479 (29.3%) implantable loop recorder, and 89 (5.5%) both. The strongest predictors of monitoring were Hispanic ethnicity (standardized LASSO coefficient, -0.19 [risk ratio (RR), 0.66]), National Institutes of Health Stroke Scale score (LASSO, -0.15 [RR per point, 0.97]), left atrial diameter (LASSO, 0.13 [RR per cm, 1.09]), and serum hemoglobin (LASSO, -0.12 [RR per g/dL, 0.97]). At the site level, the median proportion of patients who underwent monitoring was 63% (interquartile range, 36%-92%). The site-level proportion of patients with an implantable loop recorder was associated with greater likelihood of AF detection (RR, 3.9 [95% CI, 2.1-7.4]) but did not modify the trial treatment effect (P value for interaction, 0.99).

Conclusions: In the ARCADIA trial, which enrolled patients with cryptogenic stroke across the United States and Canada, nearly 60% of patients underwent prolonged heart rhythm monitoring. Use of implantable loop recorders was associated with greater likelihood of AF detection.

Keywords: atrial cardiomyopathy; atrial cardiopathy; atrial fibrillation; atrial myopathy; stroke.

Figure 1. Flow diagram of patients included in analysis of heart rhythm monitoring practices in the ARCADIA trial.

Prolonged heart rhythm monitoring was defined as external ambulatory monitors or implantable loop recorders. Baseline monitoring data refers to data on heart rhythm monitoring before randomization in the trial. A total of 116 patients had prolonged monitoring both before and after randomization. Patients with AF detected at baseline were no longer eligible for randomization, but 14 such patients included in this analysis were randomized in the trial in error. Most AF diagnoses (112/177 [65.9%]) were documented to have been made via prolonged heart rhythm monitoring. AF indicates atrial fibrillation; and ARCADIA, Atrial Cardiopathy and Antithrombotic Drugs in Prevention After Cryptogenic Stroke.

Figure 2. Distribution across sites of the proportion of patients undergoing prolonged heart rhythm monitoring.

Only sites with >10 patients in this sample are shown (96 sites had ≤10 patients and 55 had >10 patients).

Figure 3. Relationship between site‐level proportion of patients undergoing prolonged heart rhythm monitoring and detection of atrial fibrillation.

The red line represents the result of a LOWESS regression analysis of the association between site‐level heart rhythm monitoring and the probability of atrial fibrillation diagnosis. LOWESS indicates locally weighted scatterplot smoothing.