The classification of antiarrhythmic drugs proposed by Singh and Vaughan Williams in 19701, relied on the differential actions of these agents on the profile of the transmembrane action potential in isolated myocardial tissue from different species. Despite the dramatic advances over the last 15 years in understanding the molecular and ionic basis, which determine the profile of the transmembrane action potential, the original classification persists in both the clinical and government regulatory spheres. The field of Class III antiarrhythmic drug research has been illuminated by numerous publications in a most fruitful manner over the last 30 years by Professor Bramah Singh, who provides an elegant example of what is now translational medicine, ie, applying data from the laboratory to the bedside. This essay is largely based on Professor Singh’s seminal work...