A 14-year-old girl was rescued from a sudden cardiac arrest at school. Aortography disclosed mild aortic root dilation with aortic valve incompetence and subocclusion of coronary ostia and left common carotid artery. An emergency aortocoronary bypass operation was undertaken, but the patient did not recover from cardiopulmonary bypass. Postmortem disclosed massive myocardial infarction. The microscopic feature of arterial involvement was consistent with giant cell Takayasu's arteritis. The abrupt clinical presentation in this teenager with coronary ostial subocclusion is very unusual.