Most of the CAFs originate from the right coronary (52%), arise from the left anterior descending (30%), date from the left circumflex branch (18%), and over 90% of CAFs flow into the right heart [
2]. The LCX fistula is very uncommon. The early embryonic development of infection and genetic factors may cause congenital heart disease, which is the primary reason of CAF [
1]. Furthermore, coronary atherosclerosis, Takayasu's arteritis or trauma can lead to CAF [
3]. In this case, the young patient had no history of coronary artery disease, vasculitis and trauma, which indicated most likely a congenial coronary fistula. Patients with CAF can have different symptoms, such as angina, congestive heart failure, bacterial endocarditis, cardiac arrhythmia or fistula rupture [
4]. Although most patients remain commonly asymptomatic for life, CAF can enlarge and rupture [
5]. The complications of CAF include myocardial ischaemia, thrombosis and embolism, cardiac failure, atrial fibrillation, rupture, endocarditis/endarteritis and arrhythmias [
6]. In our case, the patient showed palpitation and shortness of breath, which is probably due to the contained rupture of the LCX pericardial fistula, followed by the formation of pseudoaneurysm and thrombosis. As the pseudoaneurysm continues to expand, it compresses the surrounding blood vessels, leading to poor reflux, secondary thrombosis and myocardial ischemia. It has also been reported that spontaneous rupture of aneurysmal fistula can cause haemopericardium [
6]. Without closure of fistula, this patient could be at risk of pseudoaneurysm rupture and cardiac tamponade.
Conservative treatment, medication, transcatheter intervention and surgery are used to treat CAF [
1]. Surgical closure of the CAF was preferred to treat female patients with a fistula that arises from the LCX and ends with a saccular aneurysm are at high risk of rupture, as reported by Said et al. [
7], and the perioperative mortality reported with a surgical approach is 2–4% [
4]. The possibility of rupture, a large shunt ratio, and progressive dilatation of the coronary fistulous aneurysm needs early resection of the aneurysm and closure of the fistula [
8]. In order to alleviate the symptoms and prevent the rupture of pseudoaneurysm, the patient's fistula was repaired and resected most false aneurysm wall by surgery. So far, the patient has not had any cardiovascular adverse events after the operation.
In conclusion, the huge pseudoaneurysm due to the rupture of left circumflex artery pericardia fistula is extremely rare. Early surgery can reduce the risk of cardiac tamponade because of the continuous fistula and dilated pseudoaneurysm.