The left atrial septal pouch‐Dispelling controversies

The brilliant case report published recently in Echocardiography by Ohanyan et al revealed further evidence that the left-sided atrial septal pouch (LASP), in the presence of factors which favor blood stasis in the left atrium, may be a source of intracardiac thrombotic masses.1 The septal pouch is a newly described anatomical entity that is a kangaroo-like pocket located on either the right, left, or both sides of the interatrial septum. While pouches located on the right side of the septum seem to have no clinical relevance, the LASP is considered to be a source of thrombosis and a trigger for atrial fibrillation, and both may contribute to cerebrovascular ischemic incidents.2 The existence of the LASP is a relatively new discovery, and its clinical relevance remains underrated, despite strong evidence for its involvement in the etiology of cerebrovascular events.3 Unfortunately, due to the novelty of this topic, we are still finding discrepancies and understatements, which appear in the above-mentioned case report,1 and which, in our opinion, require attention. Authors of this case report pointed out the difference in the prevalence of the LASP, which according to our previous morphological study, is 47%.4 While in the another cited study by Strachinaru et al, LASP occurred in 21% of cases.5 To understand this discrepancy, we need to refer to the methodology of these two studies in which this first study used autopsied material and the second study was a meta-analysis based on transesophageal echocardiographic reports. Until today, two imaging techniques have been used to image LASP, that is, transesophageal echocardiography and contrast-enhanced cardiac computed tomography, which are comparable techniques for detecting this structure, but still lower to the postmortem examination (LASP reported prevalence: 39.3% vs 37.3% vs 44.0%, respectively).6 Unfortunately, the authors of the report mistakenly claim that existing research does not allow for a clear indication of LASP as a risk factor for stroke.1 However, both original studies and recent meta-analysis have found a strong association between LASP and cryptogenic stroke, where risk for cryptogenic stroke was higher among patients with LASP than in cases without LASP (OR = 1.52; 95% CI = 1.15-2.00; P < .001).3,7 In the final remarks of the case report by Ohanyan et al,1 it is suggested that the presence of LASP should be investigated at every transesophageal echocardiography examination, which in the light of the latest studies,3 should make this procedure routine.