Is There a Rational Basis for the Modified Classification of Antiarrhythmic Drugs?

Abstract

Over the last 25 years a number of attempts have been made to classify antiarrhythmic drugs according to their intracellular electrophysiologic properties, their electrophysiologic properties in the intact heart (where studies could determine thresholds of conduction), and their clinical use in specific syndromes. Most of these attempts did not increase our knowledge of antiarrhythmic drugs or their clinical application. Since quinidine, introduced in the 1930’s, was the only antiarrhythmic drug available until procainamide was discovered in the mid-1950’s, no classification was necessary at first. During the 1960’s, basic electrophysiologists studied the activity of several compounds with antiarrhythmic properties on isolated cells from the heart. Miles Vaughn Williams presented a classification scheme for antiarrhythmic drugs in 1971 at an international meeting of cardiologists and electrophysiologists in Elsinor, Denmark.¹ This scheme has been widely adopted, and physicians have tried to fit new drugs into it. Vaughn Williams’ classification, and prototypical drugs for each class, are illustrated in Table 1.