A 70 year old male was admitted to the hospital 3 days after suffering one episode of ischemic chest pain. On admission he complained of non-productive cough, pleuritic pain, cardiomegaly I/IV and sinus tachycardia. Later on, he developed frequent auricular prematurities and flutter. The cardiac enzymes were elevated confirming the diagnosis of myocardial necrosis. One echocardiogram showed an important pericardial effusion. Color Doppler, high flow velocity from the lateral wall of the left atrium towards the apex, above the mitral valve. The transesophageal echocardiogram clearly showed the presence of a pathological communication at this level. One month later, a nodular image compatible with an organized thrombus was observed at the same level, sealing the rupture site.