Direct evidence from pathologic-anatomical studies in victims of sudden cardiac death has been given for acute ischemia (caused by either an acute thrombus, plaque fissuring or an organizing thrombus) to play a major role in the genesis of sudden cardiac death. Furthermore, indirect data on the effects of drugs in the setting of acute myocardial infarction have demonstrated that treating patients with beta-blocking agents is more beneficial than treating them with a pure anti-arrhythmic drug such as lidocaine. Whereas lidocaine, which also reduces the incidence of ventricular fibrillation in the setting of acute myocardial infarction, may produce an excess of mortality, beta-blockers reduce ventricular fibrillation and are associated with a prolonged survival. Further, indirect evidence on the role of ischemia in ventricular arrhythmias is given in patients with chronic ischemic heart disease by several studies on coronary revascularization and by studies on antiarrhythmic drugs versus beta-blockers in the same situation. In conclusion, there is clear evidence from studies of coronary revascularization and from studies on drug intervention in different patient populations with ischemic heart disease at risk for ventricular arrhythmias and/or for sudden cardiac death that ischemia plays an important role in the genesis of these arrhythmias.