Left Circumflex Coronary Artery-to-Right Pulmonary Artery Fistula Presenting as Recurrent Angina Despite Negative Dobutamine Stress Echocardiography: A Case Report

Introduction: Coronary artery fistulas are abnormal communications between a coronary artery and a cardiac chamber or great vessel. Fistulas connecting the left circumflex coronary artery to the pulmonary artery are uncommon, and their clinical relevance requires assessment of both anatomical and physiological characteristics. Case presentation: We report the case of a 62-year-old woman with hypertension, dyslipidemia, and first-degree atrioventricular block who presented with recurrent exertional angina. Examination revealed an early diastolic murmur at the aortic area and a prominent midsystolic murmur with a palpable thrill radiating toward the right lung base. Echocardiography showed moderate aortic regurgitation with preserved left ventricular systolic function, while dobutamine stress echocardiography showed no inducible wall-motion abnormalities. She subsequently developed recurrent angina with new T-wave inversions and mildly elevated high-sensitivity cardiac troponin T concentrations that remained unchanged across serial measurements. Coronary angiography demonstrated nonobstructive epicardial coronary arteries and a fistula arising from the atrioventricular nodal branch of the distal left circumflex artery and draining into the right pulmonary artery. Coronary steal was suspected but not physiologically confirmed. Following individualized assessment, the Heart Team recommended closure; however, the patient declined intervention and remained free of recurrent angina during approximately five months of follow-up. Conclusions: This case highlights the distinction between an anatomically confirmed coronary artery fistula and its unconfirmed physiological significance. Negative stress echocardiography and alternative potential contributors to symptoms should be considered when interpreting suspected coronary steal. Management requires individualized multidisciplinary assessment and shared decision-making.