SAFFO trial has the objective to evaluate the detection of AF or atrial flutter (AFL) as first diagnosis by implantable loop recorder (ILR) in patients with first-ever atherothrombotic or lacunar stroke. Patients with recent (30-60 days after symptom onset) diagnosis of first-ever atherothrombotic or lacunar ischemic stroke who fulfill inclusion criteria will be randomized to either continuous cardiac monitoring using an ILR plus standard cardiac monitoring (intervention arm) or standard cardiac monitoring alone (control arm) with a ratio of 1:1. The hypothesis is that the detection of of AF/AFL by using ILR will be higher than that observed by using standard cardiac monitoring. Secondary and tertiary objectives of the study include exploratory analyses on the incidence of recurrent strokes and different stroke subtypes and on the reduction of stroke risk and death from all causes in all study patients, in the two randomization groups and, in particular, in patients treated with antiplatelet therapy versus those treated with oral anticoagulant (OAC) therapy, the latter being implemented and guided by the detection of clinically meaningful episodes of AF/AFL/AT using ILR compared with standard cardiac monitoring. Moreover, this study has the objective to evaluate a clinical, neuroimaging, and echocardiographic profile predictive of AF/AFL/AT first diagnosis and stroke recurrence.