Large-artery atherosclerosis (AT), cardioembolism (CE), and small-vessel disease constitute the most common causes of ischemic stroke. However, standardized evaluation fails to detect an underlying cause in one third of ischemic strokes. Cryptogenic strokes (CS) still await to be better delineated. Here we tried to identify the similarities and differences in risk factors among patients with cryptogenic stroke, and stroke due to AT or CE.
Out of 2223 patients with ischemic stroke being followed-up in our Stroke Outpatient Clinic, 19.9% were classified as AT, 25.3% as CE, and 22.9% were due to small vessel disease. CS were diagnosed in 31.9% of patients (n=710). Patients with CS were younger than patients with AT or CE (p<0.001). Male ratio was 71.3% in patients with AT and 49.1% in patients with CE. In patients with CS, on the other hand, male ratio was 49.9%, which is similar to CE (p=0.791) but significantly different from AT (p<0.001). Hypertension was significantly lower (p<0.001) in CS (57.7%) then both AT (76.5%) and CE (71.2%). Other risk factors including diabetes mellitus, hyperlipidemia, smoking and alcohol consumption were all similar in patients with CS and CE, but significantly different from AT (p<0.001). 
The comparison of risk factors shows us there are many similarities between cryptogenic stroke and cardioembolism, while there are differences between cryptogenic stroke and atherothrombosis. On the basis of these findings, the potential mechanisms in cryptogenic stroke may be related to cardiac system, and patients with cryptogenic stroke deserve more sophisticated cardiac evaluation and prevention strategies.

RISK FACTORS IN CRYPTOGENIC STROKE