PTCA is widely practiced as the procedure of choice for revascularization of the myocardium in patients with single-vessel disease who are deemed to need intervention and is probably more widely applied than surgery would be in the same group of patients. No study has shown improved survival by intervention in such patients. The early natural history study by Oberman showed survival experience of patients with single-vessel disease, including the anterior descending, to resemble more closely patients with no coronary artery disease than those with multivessel disease. Quality of life studies including the CASS randomized study, which included 27 percent single-vessel disease patients, showed improved exercise tolerance and less need for medication in patients who received PTCA For single-vessel disease. Balloon angioplasty in single-vessel disease thus appears justified for the treatment of angina pectoris.