We report a patient diagnosed with congenital coronary artery-to-pulmonary artery fistula, giant coronary aneurysmal dilatation, and thrombosis. He received in-time surgery, and the pathology study confirmed the etiology.
CPAF, defined as the abnormal vascular communication originating from the coronary artery and draining into the pulmonary artery, accounts for 15.0–30.0% of all coronary artery fistulas (CAF), with the prevalence from 0.17 to 0.68% in the general population [3,4,5]. Most CPAF can be classified as the anterior type characterized by connecting the proximal portion of the left or right coronary artery and the anterior wall of the pulmonary artery. In contrast, the posterior type originates from the left circumflex artery or left sinoatrial node artery and drains into the right pulmonary artery via transverse sinus [6]. While CPAF is primarily congenital, it can also result from iatrogenic procedures, trauma, chest radiation, and several diseases like myocardial infarction, Kawasaki disease, and Takayasu arteritis [7, 8]. Patients with CPAF are usually asymptomatic due to the small size of the left-to-right shunts and carry a seemingly benign prognosis [2, 5]. Nevertheless, CPAF will cause symptoms suggestive of myocardial ischemia or even induce myocardial infarction when the shunts are large enough to create the coronary steal phenomenon [7, 9]. Large left-to-right shunts could also lead to pulmonary hypertension and induce congestive heart failure [4]. Besides, If other cardiac comorbidities such as patent ductus arteriosus, ventricular septal defect, valvular disease, and coronary atherosclerosis exist, CPAF might exacerbate the concomitant conditions [6]. Moreover, CPAF could complicate coronary aneurysmal dilatation, thrombosis, or infective endocarditis [10]. Notably, the incidence of coronary aneurysmal dilatation CPAF patients is around 15–35% [4, 6, 8]. CPAF with a ruptured coronary aneurysm carries significant mortalities through triggering medical emergencies such as cardiac tamponade or mediastinal hemorrhage [10,11,12].
On the aspect of diagnosing CPAF, around 47% of patients with CPAF might have continuous cardiac murmurs, best auscultated in the second intercostal space left of the sternum [7, 13]. Echocardiography could delineate CPAF’s anatomy and assess the hemodynamic changes [7]. CCTA possesses superior diagnosing capabilities owing to its non-invasiveness, relatively high spatial resolution, and 3-dimensional reconstructed imaging of the complex anatomy [4]. While coronary angiography serves as the diagnostic reference tool with its excellent visualization, it might produce false results due to the limitation of 2-dimensional projection [14]. A myocardial perfusion scan could be a valuable tool assessing hemodynamic consequences caused by CPAF [15]. Magnetic resonance imaging might also outline the conduits of CPAF [16]. Hence fully, multimodal imaging techniques are warranted for assessing and diagnosing CPAF accurately [9].
As for the treatments, surgical ligation should always be an option, especially when the patient is symptomatic, CPAF is hugely tortuous, multiple CPAFs exist, CPAF is high-flow, or CPAF combines with the giant coronary aneurysm or infective carditis [6, 17]. Endovascular embolization might also be adopted if CPAF locates proximally and consists of a single narrow drainage site without concomitant cardiac disorders requiring surgery [3, 18]. Although no consensus exists regarding the oral medication regimen, several cases utilize antiplatelet medicine, anticoagulants, beta-blockers, and calcium channel blockers to prevent thrombosis and control symptoms [2].
As for our patient, he exhibited angina pectoris in his sixties, which implicated the coronary steal phenomenon. The local hospital initially diagnosed him with the coronary aneurysm on CCTA while we modified the diagnosis to coronary-pulmonary fistula with giant coronary aneurysmal dilation through coronary angiography. He did not manifest cardiac murmurs. Having ruled out possible acquired etiologies, including vasculitis and atherosclerosis, we adopted surgery based on his persistent symptoms and concomitant large coronary aneurysm. Ultimately we performed the surgical ligation, the aneurysmorrhaphy, and the removal of the thrombus within the aneurysmal sac. The thrombus was newly formed, which could explain the adverse finding on coronary angiography 1 week ago. This unexpected finding during surgery further strengthened our decision of surgery over conservative management. Histology results of the aneurysmal wall reinforced our conviction of a congenital disorder. According to our literature search results, four cases of these three concomitant disorders have been reported. Ours is the first supported by evidence from coronary angiography, surgery, and histologic analysis. We list the invaluable experience our patient has kindly provide to us as follows: (1) integration of detailed history taking, thorough physical examination, and multimodal imaging techniques remain essential for correctly diagnosing and assessing CPAF with complex anatomy. Our patient demonstrates the need for integration because he exhibited no cardiac murmurs and presented with a false diagnosis by the local hospital. His echocardiography and chest x-ray were also negative until we conducted coronary angiography. (2) Exploring pertinent etiologies is necessary. According to other cases, Degenerated media and smooth muscle layer, suggested by the patient’s pathology report, could be attributed to the occurrence of aneurysmal dilatation [19, 20]. (3) In-time surgery poses a significant good prognosis on the patient with CPAF who meets with surgery indication. Our patient’s coronary angiography testified no signs of thrombus, while surgery 1 week later discovered new thrombus formation within the aneurysm sac. Acute embolization of the pulmonary artery or coronary artery could occur if our patient missed the surgery.
We report a rare case of congenital coronary artery-to-pulmonary artery fistula, giant coronary aneurysmal dilatation, and thrombosis. Combining these complex disorders necessitates the evaluation through multiple imaging modalities, whereas in-time surgery serves as the cornerstone for managing symptomatic patients with these combined diseases.
