Fostedil (A-53,986, KB-944) is a vasodilator acting as a calcium channel blocker which was under development for the treatment of heart conditions such as angina pectoris but was never marketed. It has antihypertensive and antiarrhythmic effects. Fostedil (A-53,986, KB-944) is a vasodilator acting as a calcium channel blocker which was under development for the treatment of heart conditions such as angina pectoris but was never marketed. It has antihypertensive and antiarrhythmic effects.