The Southern-Norway Post-Stroke Atrial Fibrillation Study

This study evaluates whether a procedure using a new wireless heart sensor patch is equal to or better than the standard hospital procedures and equipment at detecting an irregular heartbeat called Atrial Fibrillation (AF) after an ischemic stroke. Atrial fibrillation is a major cause of stroke, but it can be difficult to catch because it often comes and goes. The study will include approximately 450 adults who have had a stroke or a transient "mini-stroke" (TIA) within the last two weeks. Participants will be assigned by chance (randomized) to one of two groups: * Group 1 (Intervention): Participants wear the "ECG247 Smart Heart Sensor." This is a small patch that sticks to the chest and connects to a smartphone. It is worn continuously for up to 14 days, even after leaving the hospital. * Group 2 (Standard Care): Participants receive the standard hospital check-up. This typically involves using a "Holter monitor" (a device with wires and electrodes) for a period of about 24 to 48 hours some time after leaving the hospital. The main goal is to see if the procedure using the patch is equal to the standard procedure in detecting atrial fibrillation in participants. The study will also measure how quickly doctors can start the correct medication and how easy the patients find the devices to use.