This study aims to evaluate the clinical applicability of the AI-based lightweight ECG monitoring system (MEMO Patch Plus) as a telemetry ECG monitoring system in patients undergoing cardiac surgery. Participants will wear the MEMO Patch Plus for at least 48 hours and up to 168 hours after transfer from the intensive care unit to the general ward. The study will evaluate real-time ECG transmission, arrhythmia detection, device usability, and safety to generate preliminary evidence supporting future clinical studies.