A Rare Case of Left Main Coronary Artery Coronary Sinus Fistula in an 85-Year-Old Female

Coronary arteriovenous fistulas (CAVFs) are congenital or acquired communications between the coronary arteries and coronary venous system, and they can also include other cardiac structures or vasculature. We discuss a case of a large fistula between the left main coronary artery and the right atrium in a geriatric patient with a history of gastrointestinal arteriovenous malformations (AVM). The occurrence of CAVFs, an uncommon cardiac irregularity, is particularly infrequent among older adults. Typically, it is discovered by chance when investigating symptoms such as shortness of breath or chest pain, where coronary angiography is necessary to determine the most effective treatment strategy. This case highlights the possible utility of evaluating CAVFs in patients with a history of gastrointestinal AVM who similarly present with clinical symptoms of high-output heart failure. Once identified, this could simplify the treatment approach and improve communication between healthcare providers to minimize the risk of harm to the patient.