Anger and other negative emotions can precipitate sudden death, as shown in studies of population stressors. Clinical studies of patients with implantable defibrillators demonstrate that anger can trigger ventricular arrhythmias. Long-term negative emotions also increase vulnerability to arrhythmias. Mechanisms linking anger and arrhythmias include autonomic changes, which alter repolarization, possibly enhanced in patients with sympathetic denervation, which in turn trigger potentially lethal polymorphic ventricular tachycardias. Interventions which decrease negative emotions and resultant autonomic responses may be therapeutic in patients with implantable cardioverter defibrillators.