The primary objective of this study is to evaluate whether, in patients with first-ever atherothrombotic or lacunar stroke without any previous history of atrial fibrillation (AF)/atrial flutter (AFL)/atrial tachycardia (AT), the detection of AF/AFL/AT (silent or symptomatic) by using a continuous cardiac rhythm monitoring with implantable loop recorder (ILR) during the first 12 months of observation is higher than the detection by using a standard cardiac monitoring (physical exam, 12-lead electrocardiogram [ECG] at baseline, 3, 6, and 12 months and Holter ECG at 3 months) in the same period of time.