Case Report For reprint orders, please contact: reprints@futuremedicine.com Huge aneurysmal fistula from left main artery to right atrium in a man with atypical chest pain and dyspnea on exertion Fariba Bayat 1 , Ramin Baghaei* ,2 , Morteza Safi 1 , Zahra Ansari Aval 2 , Isa Khaheshi 1 & Mohammadreza Naderian 3,4 1 Cardiovascular Research Center, Modarres Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran 2 Cardiac Surgery Department, Modarres Hospital, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran 3 Non-Communicable Diseases Research Center, Endocrinology & Metabolism Population Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran 4 Cardiovascular Research Department, Tehran Heart Center, Tehran University of Medical Sciences, Tehran, Iran *Author for correspondence: Tel.: +982122083106; baghaei.ramin@gmail.com We present a 33-year-old man with atypical chest pain and with no significant past medical history. The patient was finally diagnosed as a case of huge fistula from the left main coronary artery to the right atrium, a very rare condition with challenging diagnostic and therapeutic approaches. The majority of cases of coronary artery fistula are small, asymptomatic and clinically undetectable; they frequently do not cause any complications and can spontaneously resolve. However, larger fistulas are frequently three times the size of a typical caliber of a coronary artery and may or may not cause symptoms or complications. First draft submitted: 26 January 2018; Accepted for publication: 6 December 2018; Published online: 8 March 2019 Keywords: atria • coronary vessels • fistula • heart Coronary artery fistulas are a subgroup of coronary anomalies that are diagnosed now more frequently due to novel diagnostic tools. Considering the natural tendency of larger fistulas to expand over time, with a gradually growing risk of thrombosis, endocarditis or rupture, the universal recommendation is to close all fistulous tracts. Serial echocardiographic or angiographic follow-up imaging to recognize enlargement of vessel in asymptomatic patients is commonly recommended [1,2]. The risk of fistula rupture or impediment has always being a notable concern in symptomatic patients and surgical repair or transcatheter intervention is recommended to abolish the aforementioned risk. Left main (LM) coronary artery fistula to cardiac chambers including right atrium is a puzzling condition, which is highly rare and diagnostic and treatment options are not available due to paucity of this circumstance [1–4]. Case presentation A 33-year-old man, who was a smoker, presented to our cardiology clinic with complaint of atypical chest pain and dyspnea on exertion (functional class II) from several months ago. On physical examination, he was alert and cooperative, had a blood pressure of 120/65 mmHg, a heart rate of 80 b.p.m., respiratory rate of 14/min and temperature of 37 ◦ C. On cardiac auscultation, a clear continuous murmur was detected, best heard in the second and third right intercostal spaces. Other remaining examinations were unremarkable. According to the finding in cardiac examination, he was subjected to transthoracic echocardiography (TTE) which showed a dilated LM artery (21 mm) and a coronary arteriovenous fistula from the LM artery to right atrium (RA) with continuous flow to RA (diastolic peak gradient = 53 mmHg, systolic peak gradient = 103 mmHg) and left to right shunt (Qp/Qs = 1.3 in TTE). The other TTE findings included normal left ventricle size, an ejection fraction of 60%, mild right ventricle size, normal right ventricle function, bicuspid aortic valve and a lack of significant valvular disease except mild mitral and tricuspid regurgitations. Transesophageal echocardiography (TEE) was performed as complementary imaging which confirmed the TTE data (Figure 1A) (Supplementary Videos 1 & 2). When we summarized the patient’s clinical status and imaging data, we were not satisfied with the diagnosis of a moderate Future Cardiol. (Epub ahead of print) ISSN 1479-6678 10.2217/fca-2018-0015 C  2019 Future Medicine Ltd