Congenital Atresia of the Left Main Coronary Artery in an Adult: An Extremely Rare Anomaly

ABSTRACT: Atresia of the left coronary ostium is one of the rarest congenital coronary anomalies. We describe a 50-year-old male with atypical chest pain and positive exercise stress 201-thallium myocardial scintigraphy, in which coronary angiography revealed atresia of the left main coronary artery and right coronary artery collateral to the left anterior descending and left circumflex arteries. The clinical features, diagnosis and management of the left main coronary atresia in adults are discussed.

J INVASIVE CARDIOL  2012;24(12):E325-E327

Key words: congenital coronary anomaly, left main coronary atresia

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Case Report. A 65-year-old man with atypical chest pains and easy fatigue was referred for coronary angiography after positive exercise stress 201-thallium myocardial scintigraphy with a small reversible defect in the anterior and posterolateral wall. The cardiovascular examination was essentially unremarkable. The chest roentgenogram and the electrocardiogram were within normal limits. The echocardiogram showed a structurally normal heart with normal left ventricular function (ejection fraction, 65%) and no regional wall motion abnormality. On selective coronary angiography, cannulation of the left coronary ostium and direct visualization of the left coronary artery (LCA) was not possible. There was a large dominant right coronary artery (RCA) providing significant intercoronary retrograde collateral to the left anterior descending artery (LAD) and the left circumflex artery (LCx) via sinus node artery branch and posterior lateral (PL) branch (Figure 1). The main pulmonary artery was not opacified through RCA injections. The coronary arteries were free of atherosclerotic stenosis and calcifications. Left ventriculography showed normal left ventricular wall motion. There was also complete absence of left main coronary artery (LMCA) from the left aortic sinus or from any other site in the aorta as shown by aortic root angiogram (Figure 2). In agreement with the clinical cardiologist and cardiac surgeon, the patient was managed medically with anti-ischemic, antiplatelet, and statin therapy. Surgical coronary artery revascularization was not recommended because the patient was mildly symptomatic, the extent of the ischemia on the thallium scan was not substantial, and the branches of the LCA were too narrow for revascularization. He received regular outpatient follow-up with only very mild symptoms 3 years after diagnosis.

Discussion. Congenital atresia of the LMCA is an extremely rare disease, with very few cases published in the literature so far.^1-4 LMCA atresia may be associated with other cardiac defects: supravalvular aortic stenosis,⁵ ventricular septal defect and pulmonary stenosis,⁶ right coronary ostium stenosis,⁷ and prolapsing mitral valve⁸ especially in infants and children. 

In this anomaly there is no left coronary ostium, the coronary arteries are otherwise positioned normally around the heart, the proximal left main trunk ends blindly and blood flows from the RCA to the left via small collateral arteries. There is usually a lack of atherosclerotic disease suggesting another cause for the absence of the LMCA.¹ In this condition, the RCA is responsible for the blood flow to perfuse the entire heart.

Congenital atresia of the left coronary ostium should be considered totally different from single (right) coronary artery, even though the RCA supplies the entire coronary circulation in both conditions. In the latter, the blood flow is always centrifugal, flowing from the center to the periphery, and from bigger to smaller arteries. On the contrary, in atresia of the LMCA, the circulation of blood in the LCA is reversed. The blood flows from the right to the LCA via one or more collateral arteries from the periphery to the center (centripetal pattern).^1,9 Coronary angiography permits the differentiation of the two conditions with ease.

Acquired atherosclerotic occlusion of the LM trunk has a similar clinical and angiographic picture in adult patients.¹⁰ In adults, it may be difficult to distinguish it from atherosclerotic occlusion of the LMCA. However, certain features are helpful. In true congenital atresia of LMCA, the coronary arteries are usually free of other atherosclerotic stenoses and/or calcifications, the RCA is usually of large size, and the re-formed left-sided arteries have a diminutive caliber, and at surgery the absence of the left coronary ostium can be confirmed.¹¹ In our case also, the RCA was very large, atherosclerotic lesions were abscent, and LAD as well as LCx were diminutive, which is diagnostic of congenital atresia of LMCA.

The collateral channels seen in atresia of LMCA include the conal branch artery (Vieussens’ anastomotic ring), the anastomoses between anterior interventricular branches of the RCA anastomosing to the LAD artery and the terminal ramifications of the posterior descending branch with retrograde flow to the terminal branch of the LAD artery at the apex of the left ventricle.⁶ 

Atresia of the LMCA shows a wide clinical spectrum, being represented in the newborn^8,12,13 as well as in elderly patients.¹⁴ It appears that LMCA atresia has an early critical stage in infancy, when the patient’s heart is not able to thrive in such an abnormal coronary situation, especially when other oxygen-consuming cardiac anomalies are present. Later on in childhood, syncope and tachyarrhythmias are the main symptoms; it could well be that collateral blood flow cannot keep up with the rapidly increasing myocardial muscle mass, resulting in myocardial ischemia. Survival to adulthood depends on the quantity and quality of collateral circulation from the RCA, the degree of development of LCA branches, and severity of coexistent congenital heart lesions, if any.

Most adult patients had a totally normal and unrestricted childhood and adolescence, and began showing symptoms only at an advanced age, even without atherosclerotic stenoses of the coronary arteries or other concomitant cardiac defects. The inadequate caliber, systolic kinking, angulating, or compression of the collateral arteries⁸ could be blamed for those symptoms, as well as the length and tortuousness of the collateral arteries, which could cause a delay in the delivery of blood to the left-sided arteries, having blood arrive during systole rather than diastole.^15,16 Development of left ventricular hypertrophy and consequent increase in myocardial oxygen demands can contribute to ischemic symptoms.⁹

Due to an unfavorable prognosis, the diagnosis of congenital atresia of the LMCA is an indication in itself for surgical revascularization. Coronary artery bypass grafting (CABG) is definitely the procedure of choice in adult patients, as mammary artery bypasses have shown superior long-term patency and great physiological adaptability to various flow patterns.¹⁷

Probably a single mammary bypass to the LAD can suffice, as the interior mammary artery (IMA) has been shown to be capable of providing a sufficient blood flow to the entire left-sided myocardium. Data from the literature support this point.^18-20 No large controlled study has been performed with the purpose of comparing hemodynamic and clinical results of single IMA grafting to the proximal LAD with double grafting to the LAD and LCx in acquired isolated LMCA disease. Therefore, the debate as to which revascularization strategy is to be considered the most appropriate remains open.

Two methods of surgical revascularization are described in children: CABG using IMA and/or saphenous vein graft and reconstruction of the LMCA with aortic wall or autologous pericardial patch. In pediatric patients, the long-term results of CABG can be questioned, especially if saphenous vein grafts are used, although good results are reported with simple IMA grafts to the LAD in children.^8,11,21 The solution of reconstructing the LMCA trunk with a baffle of ascending aorta is especially elegant.²² Although the outlook is grim, with high mortality  without revascularization,we did not decide to proceed with surgical revascularization in our case, since the patient was mildly symptomatic and stabilized on medical treatment and both LAD/LCx were rudimentary, not amenable to bypass grafting.

Conclusion. Congenital atresia of the LMCA is an extremely rare anomaly in the adult. The rarity of this lesion makes its therapeutic standardization difficult. Myocardial revascularization surgery with grafting of the internal thoracic artery seems presently to be the method of choice; however, the possibility of surgical angioplasty should be considered. Nevertheless, short-term results are encouraging and long-term follow-up becomes important for documentation of the real benefits of the surgical methods for the improvement of myocardial function.

References

1. Musiani A, Cernigliario C, Sansa M, et al. Left main coronary artery atresia: literature overview and therapeutic considerations. Eur J Cardiothoracic Surg. 1997;11(3):505-514.
2. Singh Ch, Singh H, Kumar A, et al. Congenital atresia of left main coronary artery. Indian Heart J. 2005;57(3):255-257.
3. Varghese P, Leanage RU, Peek GJ. Congenital atresia of the ostium of left main coronary artery. A rare coronary anomaly, diagnostic difficulty and successful surgical revascularization. Congenit Heart Dis. 2007;2(5):347-350.
4. Gerlis LM, Magee AG, Shepherd MN. Congenital atresia of the orifice of the left coronary artery. Cardiol Young. 2002;12(1):57-62. 
5. Rosenkranz ER, Murphy DJ, Cosgrove DM. Surgical management of left coronary artery ostial atresia and supravalvular aortic stenosis. Ann Thorac Surg. 1992;54(4):779-781.
6. Vidne BA, Nili M, Aygen M, et al. Congenital atresia of the left main coronary ostium. Scand J Thorac Cardiovasc Surg. 1979;13(1):37-40.
7. Goormaghtigh N, De Vos M, Blanquaert A. Ostial stenosis of the coronary arteries in a nine year old girl. Arch Intern Med. 1955;95(2):341-348.
8. Fortune RL, Baron PK, Fitzgerald JW. Atresia of the left main coronary artery: repair with left internal mammary artery bypass. J Thorac Cardiovasc Surg. 1987;94(1):150-151.
9. Ghosh PK, Friedman M, Vidne BA. Isolated congenital atresia of the left main coronary artery and atherosclerosis. Ann Thorac Surg. 1993;55(6):1564-1565.
10. Zimmern SH, Rogers WJ, Bream PR, et al. Total occlusion of the left main coronary artery: the Coronary Surgery Study (CASS) experience. Am J Cardiol. 1982;49(8):2003-2010
11. Leitz KH, Oster H, Keutel J. Use of the left internal thoracic artery to correct a left main coronary atresia. Thorac Cardiovasc Surgeon. 1987;35(6):345-347.
12. Byrum CJ, Blockmon MS, Scheider B, et al. Congenital atresia of left coronary ostium and hypoplasia of the left main coronary artery. Am Heart J. 1980;99(3):354-358.
13. Gay F, Vouht P, Lecompte Y, et al. [Atresia of the left coronary ostium. Repair in a 2-month-old infant]. Arch Mal Coeur. 1989;82(5):807-810.
14. Fortuin NJ, Roberts WC. Congenital atresia of the left main coronary artery. Am J Med. 1971;50(3):385-389.
15. Beretta L, Lemma M, Santoli C. Isolated atresia of the left main coronary artery in an adult. Eur J Cardiothorac Surg. 1990;4(3):169-170.
16. Dymond D, Camm J, Stone D, et al. Dual isotope stress testing in congenital atresia of the left coronary ostium. Br Heart J. 1980;43(3):270-275.
17. Singh RN, Beg RA, Kay EB. Physiological adaptability: the secret of the success of the internal mammary artery. Ann Thorac Surg. 1986;41(3):247-250.
18. Bedogni F, Castellani A, La Vecchia L, et al. Atresia of the left main coronary artery: clinical recognition and surgical treatment. Cathet Cardiovasc Diagn. 1992;25(1):35-41.
19. Lee CH, Orszulak TA, Schaff HV, et al. Flow capacity of the canine internal mammary artery. J Thorac Cardiovasc Surg. 1986;41(3):405-410. 
20. Sato S, Majima T, Kawaguchi T, et al. Congenital atresia of the left main coronary artery ostium—a case suffering from ventricular tachycardia (English Abstr). J Jap Ass Thor Surg. 1990;80(9):1474.
21. Rosenkranz ER, Murphy DJ, Cosgrove DM. Surgical management of left coronary artery ostial atresia and supravalvular aortic stenosis. Ann Thorac Surg. 1992;54(4):779-781.
22. Gay F, Vouhé P, Lecompte Y, et al. Atresia of the left main coronary ostium. Surgical repair in a two-month old infant (English Abstr). Arch Mal Coeur. 1989;82(5):807-810.

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From the Interventional Cardiology Department, Euromedica – Blue Cross Hospital, Thessaloniki, Greece.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Manuscript submitted May 29, 2012 and accepted July 3, 2012.

Address for correspondence: Christos Graidis, Interventional Cardiology Department, Euromedica – Blue Cross Hospital, Viziis Vyzantos 1, Thessaloniki, Greece. Email: chgraidi@otenet.gr