iRhythm makes and delivers ambulatory cardiac monitoring (ACM) services in the U.S. and select international markets. The core product is the Zio patch — a small, wire-free adhesive sensor worn on the chest that continuously records ECG data for up to 14 days. Physicians prescribe Zio to patients suspected of having cardiac arrhythmias, particularly atrial fibrillation. After a patient returns the patch, iRhythm uploads the ECG data to the cloud, where proprietary deep learning algorithms analyze it. Qualified technicians validate the output and send a diagnostic report to the ordering physician. iRhythm also offers Zio AT, a mobile cardiac telemetry product that transmits ECG data in real time via cellular connectivity, allowing physicians to receive timely notification of arrhythmic events during the wear period. iRhythm bills insurers and government payors for the diagnostic service — not the hardware — with roughly 83% of revenue flowing through third-party payors. Revenue is driven primarily by patch volume, with pricing set by contracted commercial rates and government reimbursement rates. iRhythm holds approximately 70%+ U.S. market share in long-term continuous monitoring and roughly 13% in mobile cardiac telemetry. Growth vectors include deeper cardiology penetration, expanding into primary care, growing the MCT business, and a nascent "innovative channel" where iRhythm contracts with value-based care organizations to proactively monitor at-risk patients. iRhythm sells directly to physician practices, hospital systems, and integrated delivery networks in the U.S., with a direct presence in the UK and select European countries and distributors in Japan.