Patient description: Karen is a 72-year-old woman with hypertension and type 2 diabetes, who was hospitalized for cryptogenic stroke two weeks ago. At the time, computed tomography was negative for brain hemorrhage and she was given thrombolytic therapy with resolution of her symptoms. Transesophageal echocardiogram and magnetic resonance angiogram of brain and great vessels found no evidence of abnormalities. She presents currently with a blood pressure of 120/70 mm Hg, normal glucose, and normal sinus rhythm on a 12-lead electrocardiogram. She reports history of occasional palpitations, shortness of breath and chest pain lasting for a few minutes and then stopping on their own.

Clinical trial eligibility criteria: eligible ages (years): 70.0-90.0,  Atrial Fibrillation Stroke Hypertension Diabetes To be eligible for the study subjects must fulfil the following at Living address in Region Zealand, Region of Southern Denmark or the Capital Region of Denmark (study subjects from other regions of Denmark who actively contact the study for participation can be included if they wish to participate) 90 years of age at the time of screening and in addition the study subject should be clinically evaluated to be biologically a potential candidate for anti-coagulation therapy and additionally have at least one of the diseases mentioned below Known diabetes mellitus (type 1 or type 2, with or without medical therapy) History with hypertension with or without a therapy that may reduce blood pressure (i.e., an increased blood pressure at randomization is not required) Heart failure: New York Heart Association (NYHA) class II-IV or a reduced left ventricular ejection fraction (< 0.50) Previous diagnosed stroke (preferably diagnosed in hospital and verified by imaging; previous (TIA, transitory ischemic attack, is not considered an criterion; a specific time interval from previous stroke to time is not required) Concerning the four qualifying diseases the study subject is considered qualified for study if he has a history of one of the diseases (for example subject is now normotensive on life-style correction or medical therapy and similarly if blood glucose has been normalised upon life-style corrections or medical therapy)  Uncorrected, congenital heart disease or severe valvular stenosis, obstructive cardiomyopathy, active myocarditis, constrictive pericarditis Recipient of any major organ transplant (e.g. lung, liver, heart or kidney) Receiving or has received cytotoxic or cytostatic chemotherapy and/or radiation therapy for treatment of a malignancy within 6 months before randomization or clinical evidence of current malignancy with the following exceptions: Basal or squamous cell carcinoma of the skin, cervical intraepithelial neoplasia, prostate cancer (if stable, localized disease with a life expectancy of > 2.5 years in the opinion of the investigator) Known to be human immunodeficiency virus (HIV) positive with an expected survival of less than 5 years due to HIV infection Renal failure treated with permanent dialysis Recent (within 3 months) history of alcohol or drug abuse based on self-reporting Any condition (e.g. psychiatric illness, dementia) or situation, that in the investigators opinion could put the subject at significant risk, confound the study results, or interfere significantly with the subject participation in the study Known atrial fibrillation irrespective of its type (paroxysmal, persistent, long-lasting persistent or permanent) Ongoing therapy with OAC or newer OAC (whereas therapy with platelet inhibitors such as acetyl-salicylic acid, clopidogrel, persantine is not considered as an exclusion) Patients who have a pacemaker (including cardiac resynchronization therapy-pacemaker, CRT-P) or implantable cardioverter defibrillator (ICD), including a Cardiac Resynchronization Therapy defibrillator (CRT-D)