A 45-year-old female patient was hospitalized for percutaneous closure of 16 mm secundum type atrial septal defect (ASD) with normal ejection fraction (68%) and without wall motion abnormality. At the 6th month control of successful closure of ASD with Amplatzer septal occluder device, transtoracic echocardiography showed depression in left ventricular systolic function with ejection fraction of 55%, and there was hypokinesia in anterior wall and apex. We performed coronary angiography. Coronary angiography showed noncritical plaques, and left ventricular apex was dyskınetic on ventriculography. It is known that left ventricular diastolic function decreases with increasing age. ASD decreases left ventricular loading due to left to right shunting of blood, and shunt may increase with age due to diastolic relaxation impairment and increased left atrial pressure. We hypothesized that relatively late closure of ASD could have increased left ventricular preload because of cessation of shunt, and diversion of all left atrial blood into the left ventricle. Left ventricular systolic and diastolic functions should be carefully evaluated before closure of ASD in relatively older ages, which is gradually decreasing due to more frequent diagnosis of congenital heart diseases at earlier ages.