A rare cause of coronary obstruction and angina pectoris
A 47 year old woman presented with characteristic exertional angina pectoris. She was previously healthy with an active lifestyle. She did not have any cardiac risk factors. Physical examination, chest x ray, ECG, and cardiolyte scan were unremarkable. Symptomatic progression over the following months led to cardiac catheterisation which demonstrated subtotal right coronary artery occlusion and 60–70% ostial left main trunk stenosis (below left) During subsequent coronary artery bypass surgery a large, firm periaortic mass partially encasing the main pulmonary artery, the right ventricular outflow tract, and the right atrium was identified. Histologic examination revealed dense collagenous fibrosis with scattered chronic inflammatory cells and fibrin deposition. No granulomas or malignant cells were identified (below centre) Inability to cannulate the aorta required off pump right internal mammary bypass to right coronary artery and left internal mammary bypass to left anterior descending artery. Postoperatively the patient’s symptoms resolved. Cardiothoracic magnetic resonance imaging showed fibrous tissue surrounding the aortic root (below right). The diagnosis of idiopathic fibrosing mediastinitis was confirmed pathologically.
Manifestations of fibrosing mediastinitis include tracheobronchial compression, oesophageal obstruction, and recurrent laryngeal and phrenic nerve injury. Cardiovascular involvement usually presents with pulmonary hypertension, superior vena cava syndrome or constrictive pericarditis. Surprisingly our patient presented exclusively with ischaemic heart disease. Absence of established risk factors for coronary artery disease requires clinicians to expand their differential diagnosis. In patients with primarily ostial coronary stenosis a congenital fibrous ridge, syphilitic arteritis, Takayasu’s arteritis, methysergide related fibrosis, radiation fibrosis, and fibrosing mediastinitis should be considered in the differential diagnosis.