Correlation Between Right-to-left Shunt And Left Atrial Enlargement In Cryptogenic Stroke

Background and Objective:A Right-to-left shunt(RLS)and left atrial enlargement(LAE)are two possible etiopathogenic mechanisms leading to cryptogenic stroke(CS).However,it is unclear whether RLS plays a role in LAE.Our study investigated the association between RLS and LAE in CS patients,and further explored the value of left atrial diameter(LAD)in predicting stroke occurrence and recurrence in CS patients with RLS.Methods:228 patients with CS admitted in the Department of Neurology,Affiliated Hospital of Mang Ping from May 2016 to June 2020 were selected as study group,as well as 236 patients with non-ischemic stroke admitted to hospital during the same period were selected as the control group.General data(age,gender,height,weight),risk factors(smoking,drinking,hypertension,diabetes,history of hyperlipidemia)and cardiac parameters(left ventricular end-diastolic dimension,left ventricular end-systolic dimension,interventricular septal,left ventricular posterior wall,left atrial diameter,left atrial minor axis,left atrial major axis,left ventricular ejection fraction,and pulmonary artery systolic pressure)of all subjects were collected.RLS was diagnosed based on contrast enhancement transcranial Doppler(c-TCD)examination.All subjects underwent transthoracic echocardiography(TTE)to assess their cardiac parameters.Patients with CS were divided into CSRLS+ group and CSRLS-group according to the existence of the RLS.CS patients with RLS were divided into large RLS group(>25 microembolus signals)and mile RLS group(1-25 microembolus signals)according to the degree of the shunt.The risk factors of cerebrovascular disease and cardiac parameters of the CS group and the control group,the CSRLS+ and CSRLS-group,and the large RLS group and mile RLS group were observed and compared.Multivariate logistic regression was used to analysis the risk factors of CS in the patients with RLS.And receiver operating characteristic(ROC)curves was used to evaluate the predictive efficacy of LAD for stroke occurrence in patients with RLS.CS patients with RLS were followed up for the recurrence of ischemic stroke.Results:A total of 228 CS patients and 236 patients in the control group were included in this study.The average age of the CS group was 51.83±10.29 years old,and that of the control group was 50.05±12.36 years old.Compared with the control group,the CS group had larger cardiac parameters(including LVDD、LVDS、IVS、LVPW、LAD、LA minor axis、LA major axis、PASP)(P<0.05),a higher proportion of male patients and a higher proportion of smokers,alcoholics,hypertension,diabetes,and hyperlipidemia(P<0.001).Among CS patients,114(50%)CS patients with RLS and 114(50%)CS patients without RLS.The LAD,LVDS,LA minor axis,LA major axis,PASP in the CS patients with RLS was larger than that in the CS patients without RLS(P<0.05),and the more severe the degree of RLS,the larger the LAD(P=0.008).There were no significant differences in other cardiac parameters,age,gender,height,weight,BMI,smoking,drinking,hypertension,diabetes and hyperlipidemia between the two groups(P >0.05).Univariate analysis was performed on RLS patients with CS and RLS patients without CS,and indicators with statistically significant differences in the results were included in multivariate Logistic regression analysis.The results showed that LAD enlargement was an independent risk factor for stroke in CS in patients with RLS [odds ratio(OR)1.480;95%CI: 1.213-1.805;P<0.001].The LAD predicted stroke in RLS at a cut-off of 37.5mm,with an area under the curve(AUC)of 0.840(95%CI: 0.77-0.893,p<0.001),sensitivity of63.2%,specificity of 84.9%.In addition,in CS patients with RLS,the 1-year and 2-year stroke recurrence risk was higher in patients with a larger LAD(≥37.5mm)than in patients with a smaller LAD(<37.5mm)(P<0.01).Conclusion:These findings suggest that compared with the control group,the CS group had LAE.The LAE in CS patients might related to the presence of RLS and the degree of shunt.LAD enlargement might be an independent risk factor for stroke,and could predict the occurrence and recurrence of stroke in patients with RLS.