Case Presentation: An 85-year-old female with a medical history of hypertension, hyperlipidemia and tobacco abuse presented to the ED with a several day history of intermittent, non-radiating substernal chest pain that occurred at rest. Physical exam revealed normal vital signs, regular cardiac rhythm, no murmurs or gallops, clear lungs, and no jugular venous distention or lower extremity edema. Initial laboratory studies showed troponin 0.049 ng/ml and creatinine 1.5 mg/dL; the remaining laboratory studies were unremarkable. An electrocardiogram showed normal sinus rhythm at 61 beats per minute with no ST-segment changes or left bundle branch block; a chest radiograph was normal. Transthoracic echocardiogram revealed abnormal left ventricular (LV) diastolic function with preserved ejection fraction of 60% and no valvular dysfunction. A subsequent coronary angiogram showed an abnormal fistula from the first diagonal artery branching off the proximal left anterior descending artery into the LV cavity. There were also left posterolateral branch arteries branching off the left circumflex artery, forming a fistula with the LV. No intervention was performed; the patient was discharged home with outpatient cardiology follow up.

Discussion: Coronary arteriovenous malformations are thought to be congenital in origin and occurring in isolation. In a large 2014 study among 6,341 patients, 0.9% was found to have a coronary artery fistula on CT angiography; 8.9% of those were coronary artery fistulae that terminated in a cardiac chamber. The most common termination sites are the right ventricle/atrium and the pulmonary artery while the LV is a rarer termination site. The majority of coronary artery fistulae are small, hemodynamically insignificant, and asymptomatic. However, coronary artery steal can occur with preferential blood flow via the relatively lower pressure system of the fistula, which can result in myocardial ischemia and symptoms of angina. Coronary angiography establishes the diagnosis and characterizes the size and features of the fistula. Therapy directed at the underlying pathophysiology, including diuretics, beta-blockers, and ACE inhibitors in cases of volume overload secondary to shunting, are often used. Current guidelines also recommend regular follow-up of small and asymptomatic fistulae to monitor for arrhythmias and to perform echocardiography every 3-5 years to monitor for chamber size enlargement. Surgical or transcatheter closure is strongly recommended for those small-to-moderate fistulae that result in myocardial ischemia, arrhythmias, ventricular systolic or diastolic dysfunction, or enlargement not due to other causes.

Conclusions: Chest pain is one of the most common cardiac complaints encountered in hospital medicine. Physicians should keep coronary anomalies in the differential of patients who present with recurrent chest pain.