Abstract Myxoma is the most common primary cardiac tumour, especially in adults. However, reports on this nosological entity in patients over the age of 80 are scarce in the medical literature. Echocardiography is a useful diagnostic tool for detecting cardiac myxomas. These tumours are usually surgically removed soon after diagnosis, limiting knowledge of their natural evolution. In this report, we describe the case of an 86-year-old woman who had been followed irregularly for arterial hypertension since 2016, when an echocardiogram showed a left atrial myxoma adhered to the interatrial septum, initially without impairment of the mitral valve (MV) or obstruction of the pulmonary veins (PV). The patient refused surgical removal at the time. Six years later, she was hospitalized for urinary sepsis. A new echocardiogram revealed an increase in the size of the myxoma, which occupied around 80% of the left atrium (LA), obstructing the PV and MV. New suggestion of surgery was refused by the patient. tumour adults However 8 literature myxomas diagnosis evolution report 86yearold yearold 86 year old 2016 septum MV (MV PV. . (PV) time later sepsis LA, LA , (LA) 201 (PV (LA 20 2

ABSTRACT A heart with three atria, totaling five chambers in all, was a fact that surprised medicine more than a century ago. This rare congenital heart defect has a very low incidence, which makes it very little known to the young generations of doctors dedicated to cardiovascular diseases. The cor triatriatum sinister is usually diagnosed in early childhood, and it is considered a congenital cause of mitral stenosis. Surgical approach is the choice to release the obstacle in order to adequate blood flow through the left atrium. We present the case of a young adult with typical symptoms of mitral stenosis, without apparent key elements on the physical examination and that the echocardiogram showed this anomaly, hardly seen and published in our field in adult patients.

RESUMEN Un corazón con tres aurículas, que sumaba cinco cámaras en total, fue un hecho que sorprendió a la medicina hace ya más de un siglo. Este raro defecto cardíaco congénito tiene muy baja incidencia, lo cual hace que sea muy poco conocido por las jóvenes generaciones de médicos dedicados a las enfermedades cardiovasculares. El cor triatriatum sinister generalmente se diagnostica en la temprana infancia y es considerado una causa congénita de estenosis mitral. La conducta quirúrgica es de elección para poder liberar el obstáculo al adecuado flujo sanguíneo a través de la aurícula izquierda. Se presenta el caso de un adulto joven con síntomas típicos de estenosis mitral, sin aparentes elementos claves al examen físico y con un ecocardiograma que evidencia esta anomalía, apenas vista y publicada en nuestro medio en pacientes adultos.