Atrial septal aneurysm. Morphological characteristics in a large population: Pathological associations. A French multicenter study on 259 patients investigated by transoesophageal echocardiography

A strong association between interatrial septal aneurysm (IASA) and stroke has recently led many authors to consider IASA as a potential cardiac source of embolism. We studied the morphological characteristics and main associations of MSA in a large cooperative study based on transoesophageal echocardiographic examinations; 259 IASA were studied in 134 men and 125 women with a mean age of 59 +/- 15 years. Fifty-five percent of IASA were found to overlap the commonly described fossa ovalis region, IASA protruded into the right atrium in 90% of the cases. They appeared thin in 81% of the patients and highly mobile in 79%. Fifty-eight percent of patients had a history of systemic embolic events, while an atrial septal shunt was detected in 61% of the patients. In patients with an embolic event, only the mobility of IASA was significantly higher than in those with no embolic event. In nine cases a pulmonary embolism was associated with arterial embolism. Furthermore, we reported three cases of paradoxical embolism. However, the true demonstration of a thrombus within the IASA was quite rare. Conclusion: IASA is probably an important risk factor for stroke. In patients with IASA and a history of embolic events, IASA may enhance migration of a thrombus constituted in situ or transiting through it. Marked mobility of IASA may also increase the risk of peripheral embolus.