Association between the left-sided atrial septal pouch and the cryptogenic stroke – an updated systematic review and meta-analysis

Cryptogenic stroke, named embolic stroke of undetermined source, refers to patients for whom the etiology of embolism remains unknown. Recently a new cardiac entity, the left-sided septal pouch (LSSP), has been identified as a possible source of thromboembolic events. In the current study, we aimed to perform a systematic review of the literature on this topic and to determine the association between the LSSP presence and occurrence of cryptogenic stroke using meta-analytical methodologies. A detailed search of electronic databases for studies that compared the presence of LSSP in subjects with cryptogenic stroke and non-stroke controls was performed. Data were extracted and pooled into a meta-analysis. We included eight studies in the meta-analysis, in which there were a total of 506 patients with cryptogenic stroke and 1600 patients in the control group. The pooled prevalence of LSSP among cryptogenic stroke patients was 31.6% (95% CI: 20.6-43.8). In the non-stroke control group the pooled prevalence of LSSP was 22.0% (95% CI: 15.0-29.8). The meta-analysis showed that there is a higher risk of cryptogenic stroke in patients with LSSP than in patients without LSSP (OR: 1.57, 95% CI: 1.23-2.01; p < 0.01). A subgroup meta-analysis of transesophageal echocardiography studies demonstrated the same association (OR: 1.59; 95% CI: 1.21-2.08; p < 0.01). In studies where the mean patient age was < 60 years, LSSP was associated with a higher risk of cryptogenic stroke (OR: 1.67; 95% CI: 1.22-2.29; p < 0.01). However, in studies where the mean patient age was > 60 years, the association was not statistically significant (OR: 1.58; 95% CI: 0.75-3.32).