Aortic stenosis (AS) can develop in a congenitally bicuspid aortic valve, or as the result of an age-related calcific degenerative disease process. Although sudden death occurs in about 20% of patients dying of AS, the mechanisms involved are not well documented. The case is reported of a 67-year-old man who experienced progressive dyspnea and persistent chest tightness for over 60 min after mountain climbing. Cardiac catheterization revealed patent coronary arteries; however, the man had severe AS. On the third day after hospital admission, he experienced a sudden loss of consciousness at the same time that torsade de pointes was recorded on the electrocardiogram. The patient was defibrillated and his vital signs restored. The corrected QT interval (QTc) prolongation seen on admission decreased toward normal after aortic valve replacement. Although the mechanism of sudden cardiac death in severe AS patients remains unclear, ventricular arrhythmia-related syncope may play a role.