Disclosed herein are various embodiments of methods, systems and devices for detecting atrial fibrillation (AF) in a patient. According to one embodiment, a hand-held atrial fibrillation detection device acquires an electrocardiogram (ECG) from the patient over a predetermined period of time. After acquiring the ECG from the patient, the device processes and analyzes the ECG and makes a determination of whether or not the patient has AF.