Accurate interpretation of 12‑lead electrocardiograms (ECGs) and continuous arrhythmia monitoring is essential for timely recognition and management of life‑threatening cardiac conditions in emergency and critical care settings. This study evaluates the level of proficiency in ECG interpretation and arrhythmia detection among nurses working in emergency departments and intensive care units. Using a cross‑sectional design, nurses completed a validated assessment that measured knowledge of ECG components, identification of common and high‑risk arrhythmias, and confidence in clinical decision‑making based on ECG findings. The results revealed notable variability in competency levels, with many participants demonstrating adequate recognition of basic rhythms but showing significant gaps in identifying complex or subtle abnormalities. Higher proficiency was associated with years of experience, prior ECG training, and regular exposure to cardiac cases. These findings highlight the need for structured, ongoing education programs and competency‑based training to enhance nurses’ ECG interpretation skills and support safer, more effective cardiac care in acute settings.​