Steal and strain: A case of coronary artery fistula presenting with coronary steal syndrome and underlying bronchiectasis

BACKGROUND: Coronary artery fistula is a relatively rare disorder with an incidence rate of 0.05–0.9%, and the majority of fistulae are detected incidentally. Most coronary artery fistulae are congenital, and the acquired variant is very rare. Herein, we present a possible acquired coronary artery to pulmonary artery fistula, most likely secondary to bronchiectasis in the adjacent lung. We will analyze the hemodynamic significance of the fistula in this case and also seek to understand the outcomes of various treatment modalities. CASE PRESENTATION: A 56-year-old male patient presented with hypoxemia secondary to acute pulmonary edema during a hypertensive emergency. He developed myocardial ischemia after treatment with diuretics and nitroglycerin, due to shunting of blood from the right coronary artery to the right lower lobe branch of the right pulmonary artery, via the fistula. This resulted in coronary steal syndrome. Coronary angiogram confirmed the fistula connecting the right coronary artery to the right lower lobe branch of the right pulmonary artery. An attempt at coil embolization was unsuccessful due to the inability to advance the microcatheter beyond the fistula. DISCUSSION: The majority of coronary artery fistulae are asymptomatic as they are hemodynamically not significant and are incidentally detected by coronary angiography, CT angiogram, echocardiogram or multi-detector row computed tomography (MDCT) with 3D reconstruction. The development of congenital fistula can be explained by the Hackensellner involution-persistence hypothesis, but the anatomy in this case and the bronchiectasis in the part of the lung adjacent to the fistula makes an acquired cause very likely due to local inflammation and the age of patient at initial diagnosis. An initial diagnosis of bronchiectasis was made at age 51, which was 5 years prior to the detection of the coronary artery fistula in this patient. Symptoms have been described mostly in the elderly and include chest pain, dyspnea, fatigue, syncope, and palpitations. Such symptomatic fistula should be treated either by percutaneous transluminal embolization or surgical ligation. CONCLUSION: This is a unique case of acquired coronary to pulmonary artery fistula in the setting of bronchiectasis in a patient in which PTE was attempted and failed. More research is required to understand the pathophysiology of acquired fistula. The decision regarding the method of closure should be individualized and decided on a case by case basis.