Congestive left ventricular failure after surgical closure of an atrial septal defect (ASD) has been repeatedly reported, particularly in the elderly. We present a case of left ventricular failure after a successful transcatheter closure of an ASD, which to our knowledge has not been described before. In a 78-year-old woman (50 kg, 160 cm) with well-preserved left ventricular function (ejection fraction 65%) and without coronary artery disease or arterial hypertension, an ASD (Qp/Qs 1.6:1) was closed with an Amplatzer Septal Occluder without a residual shunt. Two hours after the procedure, she developed pulmonary edema due to left ventricular failure (increase of end-diastolic diameter from 42 mm to 54 mm, ejection fraction 20%), had to be mechanically ventilated for 24 hours and needed catecholamines for 4 days. High doses of diuretics were supplied until the ejection fraction normalized (32%). The patient could not be discharged until two weeks after intervention. A reduced preload for decades may predispose acute left ventricular failure, particularly in the elderly with compromised ventricular compliance.