A 47-year-old woman with Kearns-Sayre syndrome (KSS) and an implanted pacemaker for complete heart block was admitted to the intensive care unit following a cardiac arrest due to ventricular tachycardia (torsade de pointes) in the setting of QT prolongation. Complete heart blocks and ventricular tachycardia are implicated as mechanisms of sudden deaths in KSS; such patients may require pacemaker implantation and implantation of an automatic implantable cardioverter-defibrillator.