The electrophysiologic effects of the antiarrhythmic drugs, presented elsewhere in this symposium, form only one of the bases for the selection of a therapeutic agent in any given clinical situation. The final choice depends on the following factors: 1. The specific arrhythmia; 2. Underlying heart disease, if any; 3. The degree of compromise of the circulation, if any; 4. The etiology of the arrhythmia; 5. The efficacy of the drug for that arrhythmia; 6. The toxicity of the drug, especially in the given patient with possible alterations in volume of distribution, biotransformation, and excretion; 7. The electrophysiologic effects of the drug; 8. The routes and frequency of administration available for that drug. As no one drug meets, or even approaches, the criteria for the ideal antiarrhythmic, a knowledge of several drugs is essential. Unfortunately, adequate, controlled clinical comparisons are virtually nonexistent. As all of the above data cannot be presented in the limited space available, only selected items will be discussed
