Even if the prognostic significance of ventricular arrhythmias (VA) has been documented in post-AMI CAD, which post-AMI patient showing VA should be treated is still controversial, because no beneficial effects of antiarrhythmic treatment has ever been proved in clinical trials using phenytoin, aprindine, tocainide, mexiletine, and the drugs recently utilized in the CAPS for EVBs. Probably, the rationale for antiarrhythmic therapy is more conclusive in patients with ventricular arrhythmias other than EVBs, and the need for antiarrhythmic drugs should be evaluated in each case, considering other clinical variables of prognostic importance (EF%, extent of coronary lesions, etc.). The type of antiarrhythmic drugs to be used is discussed, considering that, while many traditional antiarrhythmic agents are undoubtedly effective in the treatment of an acute arrhythmia, in the chronic setting, most of the time, a significant reduction in ventricular arrhythmias on Holter monitoring can be proved, without a significant reduction in total mortality. Conversely, we comment on the positive results of some empirical studies showing beneficial effects of antiarrhythmic therapy in high-risk patients reported by Lown's group. Furthermore, it can be stated that patients showing efficacy of antiarrhythmic therapy by both noninvasive and invasive evaluation of antiarrhythmic therapy efficacy had better long-term outcomes. To confirm these data, we report the results of a clinical study of the treatment of complex and frequent EVBs in cardiac patients. A different mortality on follow-up was observed in responders and nonresponders vs. patients not receiving drugs (2.2, 28, and 24%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)