We report the case of a rare anomaly of the right coronary artery originated from the middle third of the left anterior descending (LAD) coronary artery with a proximal atheromatous obstructive lesion immediately before the emergence of the right coronary artery (RCA). The patient underwent successful angioplasty with stent implantation in the left anterior descending coronary artery. Only 7 cases of this anomaly of distribution have been reported in the literature, but none of them was treated with percutaneous revascularization.Anomalies of the coronary arteries occur in 1 to 2% of the population, constituting a rare, but important, type of nonatherosclerotic coronary artery disease. These anomalies may cause sudden death on exertion and increase the risk of coronary arterial trauma during surgical procedures. In addition, certain types of anomaly may lead to myocardial ischemia 1 .The single coronary artery (SCA), described as an isolated coronary artery, has no gender predominance, being a rare entity with an incidence of 0.024% when isolated, and of 0.03 to 0.04% when associated with other cardiac abnormalities 2-4 . Its main characteristic is being originated from the aortic root through a single ostium, with no evidence of a second ostium, being then responsible for the irrigation of the entire heart, independently of its distribution 2 . In these cases, proximal atherosclerotic obstructions may have severe consequences for the patient 4 .We report the case of a patient who underwent percutaneous coronary intervention with stent implantation and whose RCA originated from the LAD. The cases of only 7 patients with that anomaly have so far been reported in the literature, but none of them was treated with coronary angioplasty 5 . Case ReportThe patient is a 73-year-old, white, male, retired lumber jack, bornt and residing in the town of Maria da Fé, in the state of Minas Gerais. The patient has type II diabetes, hypertension and quit smoking 20 years earlier. He was referred to our service for coronary angiography due to a one-year history of oppressive chest pain on exertion, which irradiated to the left upper limb, was relieved with rest, and had no aggravating factors. The patient reported that in the preceding 2 months the pattern of the chest pain evolved progressively until being triggered at rest.On physical examination, the patient had no alterations, except for his cardiac auscultation, which had a regular cardiac rhythm with the presence of S4. The chest teleradiography was normal. The rest electrocardiogram ( fig. 1) showed a sinus rhythm, SÂQRS +70º, heart rate of 75 bpm, with no ventricular repolarization alterations. During the exercise test ( fig. 2), a significant 3-mm depression of the ST segment was observed on the MC5 lead with a load of 1.7 mph 10% at 3 minutes, characterizing an ischemic myocardial response to exercise.The patient underwent coronary angiography according to the Sones technique on July 14th, 2003, which revealed a LAD originating from the left Valsalva sinus, and dividin...