Cryptogenic stroke, embolic stroke of unknown source, and the left atrial septal pouch: the role of transesophageal echocardiography.

Background: Cryptogenic stroke accounts for a substantial proportion of ischemic strokes and often poses a diagnostic challenge due to the limitations of the TOAST classification in identifying atypical mechanisms. The left atrial septal pouch (LASP) is a blind-ended pouch arising from the incomplete fusion of the septum primum and septum secundum and is mutually exclusive with a patent foramen ovale (PFO). LASP is typically diagnosed using transesophageal echocardiography (TEE), an imaging modality not routinely utilized in the evaluation of either cryptogenic stroke or a related entity, embolic stroke of unknown source (ESUS). Consequently, LASP may be underdiagnosed and unrecognized as a potential risk factor. We examined the association between LASP and cryptogenic stroke.

Materials And Methods: We searched PubMed and EMBASE to identify relevant studies. The association between LASP and cryptogenic stroke was estimated by the odds ratio (OR) (unadjusted) and 95 % confidence interval (CI). Heterogeneity was assessed by χ-based Q-test.

Results: Eight studies with 2,075 participants were used in the meta-analysis. We found a significant association between cryptogenic stroke and the presence of LASP (OR 1.60, 95 % CI 1.27 to 2.02, p < 0.001). No evidence of heterogeneity was found (Q = 6.33, p = 0.50). Seven of the eight studies utilized TEE for LASP detection.

Conclusion: This systematic review and meta-analysis supports a relationship between LASP and cryptogenic stroke. Given the limitations of the TOAST criteria and the underutilization of TEE in stroke evaluation of cryptogenic stroke and ESUS, further research is needed to characterize LASP's role in stroke occurrence and to establish targeted prevention strategies in affected patients.