Intercoronary communication: a rare coronary anomaly.

Background: Intercoronary communication also known as coronary arcade or coronary cascade is a rare coronary artery anomaly with an incidence of only 0.002% in patients undergoing angiography. This case emphasizes the importance of recognizing this rare anomaly and highlights its clinical significance.

Case Presentation: We report a case of intercoronary communication in a 56-year-old female who presented with acute chest pain and ST-segment depression in the lateral leads. High-sensitivity troponin-T was elevated and transthoracic echocardiography revealed normal left ventricular function with no regional wall motion abnormality. Hence, the diagnosis of acute coronary syndrome - non-st-elevation myocardial infarction was considered. Coronary angiography revealed a 95% focal stenosis in the major obtuse marginal artery (OM). The right coronary artery (RCA) angiogram revealed a single abnormal channel communicating the right posterolateral branch (PLV) and the distal left circumflex artery (LCX) with retrograde opacification of the proximal LCX, left main coronary artery (LMCA) and left aortic sinus. After she underwent revascularization with the drug-eluting stent to the OM. CT-coronary angiography confirmed the presence of intercoronary communication (ICC) between the right posterolateral branch and the distal LCX artery. No active intervention was done for the ICC. Over a year of follow-up, our patient remained asymptomatic.

Conclusions: Angiographically and anatomically, collaterals and intercoronary communications should be differentiated. Obstructive coronary artery disease leads to the development of collaterals, which are typically less than 1 mm in diameter, multiple and tortuous. However, ICC tends to be single and straight, usually seen without obstructive disease with unidirectional or bidirectional flow. Histologically, collaterals consist of endothelium supported by poorly organized collagen, muscle and elastic fibers. Meanwhile, ICCs resemble epicardial vessels in that they have a well-defined muscular layer. This case emphasizes the importance of recognizing this rare coronary anomaly and distinguishing it from collaterals to help in accurate diagnosis. Although they can provide an efficient blood supply to the jeopardized myocardium and can aid as a channel during coronary interventions, they can also cause myocardial ischemia by coronary steal.