Incidental Discovery of a Right Atrial Diverticulum in an Adult Patient.

Background and Clinical Significance: Congenital malformations of the right atrium are rare. Their clinical presentation varies widely, from the absence of symptoms to sudden death, often being diagnosed incidentally by cardiac imaging. First described in 1955, the right atrial diverticulum is usually characterized as a pouch-like structure originating from the free atrial wall, or right atrial appendage. The prevalence of congenital malformations of the right atrium is unknown because few clinical cases have been reported. Associated complications include arrhythmias, pulmonary thromboembolism, progressive dilatation marked by a high risk of compression and rupture. In these cases, the optimal therapeutic approach is surgical resection. Case Presentation: We present the case of a 58-year-old, hypertensive female with a history of COVID-19 (Coronavirus Disease 2019), who was admitted for persistent dyspnea and chest pain. An electrocardiogram on arrival showed no arrhythmias or ischemic changes, and echocardiography revealed severe systolic dysfunction-a left ventricular ejection fraction (LVEF) of 20%, moderate mitral and tricuspid regurgitations, and a pericardial collection, adjacent to the right atrium, considered to be a localized pericardial effusion. Coronary angiography excluded ischemic etiology and a viral myocarditis was further suspected. Cardiac magnetic resonance imaging (IRM) showed a non-ischemic scar pattern in the interventricular septum, but also detected a well-defined large mass, which communicated with the right atrium through a 20 mm opening, suggestive of a right atrial diverticulum. Contrast echocardiography confirmed the communication between the cavity and the right atrium. A surgical resection of the large diverticulum was performed. Conclusions: The particularity of this case consists in the incidental identification of a rare cardiac malformation in an adult patient.