The ARIES study is an observational study in which patients with a recent acute ischemic stroke of cryptogenic aetiology are consecutively enrolled in order to perform a extensive cardiologic work-up. The main objective is to study parameters that could predict arrythmias on prolonged monitoring and also echocardiographic parameters of left atrial disfunction that could predict the presence of a hidden atrial fibrilation and recurrent ischemic events in patients with cryptogenic stroke.

Cerebrovascular diseases are the second most frequent cause of death in the general population, representing a 10% of global death. In order to prevent recurrent strokes, it is crucial to identify the underlying cause to administrate the best treatment in secondary prevention. Cryptogenic strokes are those in which the etiology remains unknown despite performing an extensive work-up; they represent between 20-62% of strokes. Occult atrial fibrilation is thought underlie up to 40% of cryptogenic strokes; it has also reciently been postulated that other left atrial arrythmias (parafibrilatory status) and left atrial markers of disfunction could represent a cardiac source of emboli.

Tha hypothesis of the ARIES study is that an extensive cardiologic work-up (advanced echocardiography measuring strain /stain rate and 3D echo and a 30 day continuos ECG monitoring) would detect atrial disfunction, parafibrilatory status and atrial fibrilation in patients with cryptogenic stroke, and that patients with these findings could have more stroke recurrences. This study is designed as a prospective observational unicentric study that includes patients with cryptogenic stroke in a consecutive matter in La Paz University Hospital.

Inclusion Criteria:

• Patients addmitted to the Neurology service at La Paz University Hospital with a recent diagnosis of cryptogenic stroke considered non-lacunar and where no other reasonable diagnosis is suspected.
• Signed informed consent.

Exclusion Criteria:

• Presence of large vessel atheromatosis with >50% estenosis, or <50% but with two or more vascular risk factors (age > 50 years old, hipertension, diabetes mellitus, dyslipidemia, smoker).
• Patients with a un favorable clinical situation or dependance who will not benefit from the study or those that could not fullfill study visits and procedures.
• Patients in which an embolic arrythmia has already been demonstrated

Patients older than 50 years old addmitted to the neurology ward in La Paz University Hospital with a recent diagnosis of cryptogenic ischemic stroke.