AIM   To investigate the correlation between patent foramen ovale (PFO) and cryptogenic ischemic stroke (CS),and to evaluate its screening value.

  METHODS   A retrospective analysis was performed on patients who were treated for cryptogenic ischemic stroke in our outpatient department and the Department of neurology clinic from June 2018 to December 2019.According to TOAST classification, a total of 141 patients were diagnosed as CS group, during the same period, 76 patients who were excluded from stroke as control group. CS group and control group were divided into two groups according to the age, young and middle-aged group (< 55 years old) and elderly group (≥ 55 years old). All patients underwent head CT or MRI to diagnose ischemic stroke, and routine biochemical examination, neck vascular ultrasound, double lower extremity vein ultrasound were performed to eliminate other risk factors that may cause stroke. All patients were examined by contrast transthoracic echocardiography (cTTE) to screen PFO. After cTTE primary screening PFO-RLS positive, Transthoracic echocardiography (TTE) and Transesophageal echocardiography (TEE) were used to confirm the diagnosis of PFO. Furthermore, the comparison of PFO-RLS between CS group and control group, and the comparison of PFO-RLS in CS group of different ages were analyzed, the evaluation index was calculated by using the four-lattice table method.

  RESULTS   There were 141 patients in CS group, including 83 young and middle-aged patients and 58 elderly patients. A total of 76 patients were in the control group, including 54 young and middle-aged patients and 22 elderly patients. The positive rate of PFO-RLS was 63% in the CS group, and that in the control group was 17%,and the positive rate of PFO-RLS in CS group was significantly higher than that in the control group (P<0.01). The positive incidence rate of PFO-RLS in the young and middle-aged CS group was 65%, and the positive incidence rate of PFO-RLS in the elderly CS group was 60%. The difference in the positive rate of PFO-RLS in the two age groups of CS was not statistically significant. At last, 102 patients with positive PFO-RLS were excluded from other congenital heart diseases by routine TTE, and all 102 patients with positive PFO-RLS were examined by TEE, which was finally confirmed to be PFO. The sensitivity, specificity and positive predictive value of PFO-RLS were 63%, 83% and 87% respectively by cTTE primary screening..

  CONCLUSION   ①PFO-RLS is closely related to CS. ②c-TTE is easy to operate and can be used as a primary screening method of PFO.