The original clinical investigators of percutaneous transluminal coronary angioplasty (PTCA) are now into the fourth year of their experience.1-4 Since the first PTCA performed by Gr眉ntzig and co-workers1 in Zurich, Switzerland, in 1977, more than 3,500 of these procedures have been attempted in Europe and in the Western hemisphere. As with most new therapies, the question properly arises: When does such a technique safely move from the investigative stage to responsible clinical practice? Gr眉ntzig, Myler, and Stertzer are now able to show an approximate 85% sustained patency rate in a series of single-vessel cases of PTCA followed up for 36 months.5 Moreover, many patients are pain free, have normal results from a thallous chloride Tl 201 scan during exercise, and have normal angiograms 40 months after PTCA. It also seems that the majority of single-vessel recurrences after PTCA are readily and safely disposed to successful second dilation,