The past 10 years have seen a remarkable change in the approach to cardiac arrhythmias, from a position of confidence and a feeling of well-being about pharmacological treatment to a situation in which there is now marked uncertainty and general apprehension about the role of antiarrhythmic drugs. Until relatively recently the prevailing concept in antiarrhythmic therapy was that arrhythmias could be controlled by drugs which slowed conduction or suppressed automaticity, goals well served by the sodium channel-blocking drugs and glycosides. Drug re search was based largely on the development...