PTCA was first applied to human coronary disease in 1977. There have been major advances in catheter design, balloon construction, and identification of both high and low risk patients for this procedure. Experienced angioplasty teams can now successfully dilate severe lesions in more than 90 percent of patients attempted. This success rate can be achieved with less than one percent operative mortality and less than five percent myocardial infarction and/or emergent coronary artery bypass graft surgery. However, as many as one-third of successfully dilated patients will experience the return of angina within the following six months to one year, reflecting restenosis of the dilated lesion. Most of these individuals can successfully undergo a second dilatation.