Coronary artery fistula (CAF) is a rare congenital or acquired condition that involves an abnormal communication between a coronary artery and either a cardiac chamber or a great vessel around the heart. Coronary-pulmonary artery fistulas account for 15-30% of CAF cases. In general, larger CAFs present clinical relevance, focusing mainly on the mechanism of coronary steal phenomenon, and causing angina and dyspnea associated to coronary steal and, rarely, to myocardial dysfunction. We report the case of a 55-year-old woman with a history of arterial hypertension, poor adherence to treatment, and no history of surgeries, cardiac events or trauma. She was admitted to the emergency room with a 24-hour history of moderate, pulsatile, holocranial headache, and moderate to severe oppressive retrosternal pain radiating to the shoulder and left arm, with dyspnea and generalized pallor. Physical examination revealed blood pressure 200/70 mmHg, breathing rate 20 cpm, and arterial oxygen saturation 94%. ECG showed sinus rhythm, 58 bpm, negative T waves in anteroseptal and high lateral wall, and absence of Q waves. Laboratory data: Troponin T 82 ng/mL, CK-MB 9.34 ng/mL. Transthoracic Doppler echocardiography revealed left ventricular ejection fraction (LVEF) 60%, apical hypokinesis, grade I diastolic dysfunction, absence of pericardial effusion or intracavitary thrombi, and no pulmonary hypertension (PH). The patient was referred to the Interventional Cardiology Department with a diagnosis of non-ST segment elevation acute myocardial infarction (AMI). Coronary angiography (CAG) targeted no lesions in epicardial coronary arteries and a coronary fistula originating from the distal segment of the right coronary artery (RCA) and draining into the right pulmonary circulation, a medium-sized vessel with a caliber of 2.5 mm in the proximal portion . Left ventriculography showed apical and inferoapical hypokinesis and slightly decreased contractile reserve. Percutaneous embolization beyond the first curve of the fistula using 3 coils (4.0 mm x 7 cm, 5.0 mm x 10 cm and 3 mm x 9 cm) was successfully performed without complications, confirmed by the final angiography . The patient was discharged asymptomatic and with ECG improvement on the third day of hospitalization . ECG showed preserved systolic function, normal pulmonary pressure, and no wall contractility abnormalities. The first reported case of a coronary artery fistula was in 1865 by Krause; it is mostly a congenital vascular malformation of relatively low incidence -0.3% of congenital heart disease-, but it is the most common hemodynamically significant congenital defect of the coronary arteries, comprising the 13-14% of the angiographically recognized coronary artery anomalies.  Most CAFs originate from the RCA or anterior descending artery, and drain into low-pressure structures including right-sided chambers, pulmonary artery, superior vena cava, and coronary sinus. CAFs are usually small, asymptomatic, and are diagnosed incidentally on imaging tests. CAFs often close spontaneously; however, larger or multiple CAFs-depending on the degree of severity of the shunt or coronary sequestration- are associated with symptoms such as fatigue, dyspnea, palpitations and/or angina. (2, 6) Possible complications include volume overload, myocardial hypertrophy and congestive heart failure, or myocardial ischemia/infarction in the absence of coronary atherosclerosis, arrhythmias, PH, endocarditis or rupture. In our case, we concluded that angina was due to increased myocardial oxygen requirement secondary to high blood pressure. Mechanically, we considered that anteroapical myocardial ischemia was caused by a steal effect to the anterior descending artery circulation through the septal branches, since the fistula originated from the distal segment of the RCA. Our classification was type-2 AMI due to elevated cardiac enzymes. Medium-sized CAFs should be closed in symptomatic patients, while larger CAFs should be closed regardless of symptoms. Therapeutic strategies depend on the anatomy of the fistula, its clinical presentation and the team's experience, and a surgical or percutaneous technique can be chosen, considering the risk and feasibility of the procedure. Despite the recommendation of surgical ligation over coil embolization,  following an individualized approach was beneficial. In conclusion, CAF is the most common congenital anomaly of hemodynamically significant coronary arteries. We recommend treating all medium-sized CAFs. Over the years, this entity may lead to further growth of the artery, resulting in further concomitant cardiac disorders and therapeutic complexity.