[Prevalence of structural abnormalities of the atrial septum and their association with recent ischemic stroke or transient ischemic attack: echocardiographic evaluation in 18631 patients].

Background: Ischemic stroke is one of the most frequent causes of morbidity and mortality in industrialized countries. In more than 40% of cases the cause of the ischemic event is not recognized, especially in young patients in whom, moreover, the presence of a structural abnormality of atrial septal aneurysm (ASA) and patent foramen ovale (PFO) is more frequently reported. The prevalence of this two minor atrial septal defects is strongly related to the study population (unselected patients and patients with recent ischemic stroke/transient ischemic attack-TIA) and to the diagnostic tool employed (transthoracic echocardiography--TTE or transesophageal echocardiography--TEE).

Methods: We retrospectively evaluated the prevalence of ASA in 16,836 patients who underwent TTE from January 1, 1994 to June 30, 2002. During this time period we also evaluated the prevalence of ASA, PFO and their association in 1795 patients in whom a TEE was performed. The patients who underwent TEE were divided into two groups: group A included 430 patients with recent stroke/TIA or suspect cardioembolic event, and group B included 1365 patients as controls.

Results: An ASA was detected in 1.6% of the whole study population; 0.7% of the patients underwent TTE and 10.2% of the patients underwent TEE. In group A the prevalence of ASA was 24%, in group B 4.7% (p < 0.001). A PFO was identified in 9.9% of patients in whom a TEE was performed; the rate was 24% in group A and 5.3% in group B (p < 0.001). In a subgroup of 65 patients, < 60 years (mean age 45 +/- 8 years), with cryptogenic or unexplained stroke/TIA a TEE examination identified the presence of ASA, PFO and their association in a rate of 20, 15 and 34%, respectively.

Conclusions: Our data show, in a large study population, a prevalence of ASA and PFO not negligible. The association of this two atrial septal abnormalities in patients with stroke/TIA, especially those classified as cryptogenic, suggests to study in depth these minor atrial septal defects and in particular: 1) to standardize ASA definition; 2) to identify the etiopathogenetic mechanisms leading to embolic events; 3) to define the best pharmacological treatment.