Congenital atresia of the left main coronary artery with atherosclerotic chronic total occlusion of the right coronary artery: A rare association

A 68 yr old diabetic male□, admitted in February 2020 with recent onset effort angina for two months to the department of Cardiology, Yashoda Hospitals, Hyderabad, India. Electrocardiography and echocardiography were unremarkable. Coronary angiography was unable to selectively engage the left main coronary artery (LMCA), while aortic root angiography substantiated it (Figure A and B). As a result, congenital atresia in the LMCA was suspected, which was corroborated by the existence of two well-formed, long sinuous collaterals feeding the entire left coronary circulation from the ostial segment of the right coronary artery (RCA). The mid-segment of the left anterior descending artery (LAD) was supplied by the larger feeding vessel, while the small calibre feeding vessel supplied the obtuse marginal artery (Figure C and D).

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Figure (A and B) Conventional coronary angiography was unable to selectively engage the LMCA, whereas non - selective injection of the LCS and AO angiography could not locate the LMCA. (C and D) The two-collateral circulations, well-formed collateral supplying the entire LCA from the RCA (dotted right to left arrow) and a network of collaterals supplying the RCA from the LCA (dotted left to the right arrow. (E ) CT angiography confirmed the finding with atherosclerotic CTO of the RCA (dotted white circle;). (E and F) Two feeding vessels (number 1, 2) supplied the LCA (dotted right to the left arrow). AO, aorta; CT, computed tomography; CTO, chronic total occlusion; LCS, left coronary sinus; LCA, left coronary artery; LMCA, left main coronary artery; LAD, left anterior descending artery; LCX, left circumflex artery; RCA, right coronary artery.

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In addition, the ostio-proximal segment of the RCA exhibited an atherosclerotic chronic total occlusion, resulting in several septal and epicardial collaterals from the LAD and circumflex arteries. Computed tomography confirmed the findings (Figure E and F). He underwent coronary artery bypass surgery successfully. He has completed one year follow up with no further symptoms.

There have been 43 adult cases of congenital LMCA atresia recorded so far in the literature, with nine of them having atherosclerotic coronary artery disease. The diagnosis is usually elusive, and the initial manifestation may be sudden cardiac death. If sufficient collateral circulation has developed from other branch arteries, it may be detected inadvertently during echocardiography and stress tests.