iRhythm Technologies announces results of GUARD-AF study Page 1

• Results of the GUARD-AF study presented at the 2024 Congress of the European Society of Cardiology (ESC)
• Using iRhythms Zio GUARD-AF is a patch-based long-term monitoring (LTCM) and the largest randomized trial in primary care to evaluate the impact of screening for undiagnosed atrial fibrillation (AF).
• Demonstration with Zio from iRhythm XT¹ LTCM resulted in an increase in new diagnoses of atrial fibrillation (5.0% versus 3.3%) at a mean follow-up of 15 months.
• No difference between hospital admission after stroke and standard care in the context of reduced statistical power due to shortened enrollment and follow-up.

SAN FRANCISCO, Sept. 1, 2024 (GLOBE NEWSWIRE) — iRhythm Technologies, Inc. (NASDAQ:IRTC), a leading digital health company focused on developing trusted solutions to detect, predict and prevent disease, today announced the presentation and release of the GUARD-AF (ReducinG Stroke through screening for UndiAgnosed atRCardiac fibrillation in the elderlyDiRhythm provided the Zio XT Patch ECG Long-Term Continuous Monitoring (LTCM) monitor, which was used in the interventional (screening) arm of the study.

GUARD-AF was a prospective, randomized, parallel-group control trial that evaluated whether screening for atrial fibrillation in people aged ≥70 years with an approved 14-day Zio XT single-lead LTCM could identify patients with undiagnosed atrial fibrillation and reduce stroke. Participants were randomized 1:1 to screening with Zio XT LTCM or usual care. The primary efficacy and safety outcomes were hospitalizations for any stroke or bleeding, respectively.

During a median follow-up of 15 months in 11,905 enrolled patients from 149 primary care facilities in the U.S. (5,952 were assigned to screening), the study found that Zio XT LTCM resulted in an increase in new diagnoses of atrial fibrillation compared to usual care (5.0 vs. 3.3%) by the end of follow-up. There was no significant difference between the groups in the incidence of the primary endpoint of hospitalization for stroke, although event rates were low and the study was stopped before the planned total of 52,000 patients could be enrolled during the COVID-19 pandemic²which reduces statistical power. The results were presented by Dr. Renato Lopes, Professor of Medicine at the Duke Clinical Research Institute and Duke University, at the ESC Congress on 1 September and simultaneously published in two tandem manuscripts in Journal of the America College of Cardiology (JACC)³ and the JACC: Clinical Electrophysiology.⁴