2026 Scientific Sessions

Title:
Stolen from the Coronaries: Left-to-Left Shunts Presenting as Chest Pain Syndrome!

Introduction:
Coronary artery fistulas (CAFs) are abnormal communications between a coronary artery and a cardiac chamber or great vessel. They occur in approximately 0.002% of the general population and most commonly arise congenitally. In about half of cases, the fistula originates from the right coronary artery, while approximately 42% originate from the left coronary system. The majority of CAFs drain into right-sided cardiac chambers or the pulmonary circulation. Although many CAFs remain asymptomatic, hemodynamically significant fistulas can lead to clinical manifestations through the coronary steal phenomenon, where blood preferentially flows through a low-resistance fistulous tract rather than the myocardial microcirculation. This can result in myocardial ischemia, arrhythmias, heart failure, and other complications. We present a rare case of dual coronary artery fistulas forming a left-to-left shunting mechanism that manifested as a chest pain syndrome.

Clinical Case:
A 61-year-old woman with a history of hypertension and dyslipidemia presented to the emergency department with sudden onset substernal chest pain radiating to the left arm and jaw, accompanied by diaphoresis. Vital signs and cardiovascular examination were unremarkable. Laboratory studies demonstrated an elevated troponin level, while electrocardiography showed normal sinus rhythm without clear ischaemic changes. Echocardiography revealed preserved left ventricular systolic function and no wall motion abnormalities. Coronary angiography demonstrated no obstructive coronary artery disease but revealed two CAFs. One originated from the proximal left anterior descending artery (LAD) and the other from a separate ostium within the right coronary sinus. Both fistulous tracts drained through arteriosinusoidal channels toward the left atrial appendage and pulmonary artery region, creating parallel shunts. To determine the physiological significance, the patient underwent exercise stress echocardiography. During exercise she developed chest tightness with electrocardiographic changes and inducible wall motion abnormalities in the circumflex territory, consistent with myocardial ischemia secondary to coronary steal. The patient subsequently underwent transcatheter coil embolization of the LAD fistula using hydrostatic embolization coils with successful occlusion. At one-year follow-up, she remained asymptomatic with preserved ventricular function and negative stress testing.

Discussion:
CAFs draining into cardiac chambers are uncommon and identified in approximately 0.08–0.3% of patients undergoing coronary angiography, with fistulas involving left-sided chambers particularly rare. Symptoms depend on the degree of shunting and may include fatigue, dyspnoea, arrhythmias, myocardial ischemia, or heart failure. The underlying mechanism often relates to coronary steal, where blood preferentially flows through the low-resistance fistulous tract rather than the coronaries. Management strategies depend on symptoms and haemodynamic significance. Asymptomatic fistulas may be monitored conservatively, whereas hemodynamically significant fistulas causing myocardial ischemia or complications warrant intervention. Treatment options include transcatheter embolization or surgical closure. Percutaneous coil embolization has emerged as an effective minimally invasive therapy with favourable short- and long-term outcomes. This case illustrates a rare cause of chest pain syndrome due to dual coronary artery fistulas producing coronary steal. Recognition of this entity is important when evaluating patients with anginal symptoms in the absence of obstructive coronary artery disease.