497 Multimodality imaging of an evergreen conundrum: true or false aneurysm of the left ventricle?
Authors: Garau E , Cocco D , Corda L , Palmisano V , Porcu M , Manca M , Lixi G , Cirio E M , Meloni L , Montisci R 
Published: January 2020

Abstract
In case of transmural necrosis following STEMI, the myocardial wall may develop a true or false aneurysm. While the former usually has a benign course, the latter has a propensity to rupture leading to an ominous prognosis. We report the case of a patient with a recent inferior STEMI complicated with LV aneurysm of the inferior wall, initially diagnosed as a false aneurysm. We describe the case of a 77-year-old man affected by hypertension, diabetes and AF. Two months before he experienced an inferior STEMI treated with late (&gt;12 hours from symptoms onset) pPCI and implantation of a DES on the RCA and the postero-lateral branch. TTE showed a mildly reduced LV systolic function (EF 50%) due to akinesia of the inferior wall. The patient presented to the ED for recurrent syncopes at rest. Vital signs were unremarkable. Troponin and electrolytes were within normal range. ECG showed a normofrequent sinus rhythm and Q waves with persistent ST elevation in the inferior leads. TTE showed a suspected rupture of the inferior wall in the middle segment between the posterolateral papillary muscle and the mitral annulus. The rupture seemed to be contained by the pericardium so as to create a huge cavity communicating with the LV through an apparently small neck and refurnished with turbolent blood during the cardiac cycle. In the suspicion of a pseudoaneurysm ( an urgent cardiac CT was performed. CT showed an extraventricular cavity apparently contained by the pericardium with a narrow neck and a pericardial effusion of a high density liquid. A diagnosis of post-infarction pseudoaneurysm was made. The day after the patient was stable but TTE showed a mild increase of the size of the "pseudoaneurysm", hence the Heart Team referred the patient to the cardiac surgery department for an urgent repair. In the surgical room TOE displayed the large cavity rising from the inferior wall of the LV and the communication thorugh a large neck. The intraoperatory finding was, unexpectedly, a true aneurysm of the inferior wall. The redundant aneurysm was excised and the defect was succesfully closed with a bovine pericardium patch. No periprocedural complication was recorded and the postoperatory period was uneventful. The present case strikingly shows how a mechanical complication may develop in spite of myocardial revascularization. The high level of suspicion led to a strong effort to achieve a definite diagnosis. Multimodality imaging plays a pivotal role and is warranted since the initial evaluation with TTE may be inconclusive. CT has a high diagnostic yield but false positives may happen. MRI could have been more specific in our case, but the clinical evolution and the CT images led us to be confident in referring the patient to an urgent cardiac surgery. In conclusion, the non invasive differential diagnosis between true and false aneurysm still remains a modern challenge.
Abstract 497 Figure. Multimodality imaging of a LV aneurysm