Authors
Dr Matthew Morgan1, Dr Abbas Ausami1, Dr John Rawlins1
1-University Hospital Southampton NHS Foundation Trust, Southampton, UK
Case history
88yo male presenting with exertional breathlessness and new murmur. Initially investigated with an echo which demonstrated severe aortic stenosis and moderate aortic regurgitation. As part of his work up for TAVI (transcatheter aortic valve implantation), he was referred for coronary angiography and CT coronary angiogram. The patient was found to have a congenital absence of his RCA, with the territory being supplied by a superdominant circumflex artery.
Figure 1 – 3D CTCA reconstruction of the heart from above, demonstrating single coronary origin off the left coronary cusp.Left image: heart and coronary vessels. Right image: coronary vessels with the heart subtracted.
Figure 2 – 3D CTCA reconstruction demonstrating the posterior heart, with a dominant circumflex wrapping round the atrioventricular groove to supply the RCA territory. Left image: heart and coronary vessels. Right image: coronary vessels with the heart subtracted.
Figure 3 – Left image: Coronary angiography demonstrating cannulation of the left mainstem with LAD descending vertically and dominant circumflex wrapping round to supply the RCA territory. Right image: 3D CTCA reconstruction of the coronary arteries demonstrating the same anatomy.
Multiple choice questions
Which of the following congenital abnormalities are associated with absent RCA?
- Bicuspid aortic valve
- Atrial septal defect
- Aortic coarctation
- Hypoplastic left heart syndrome
- Tetralogy of Fallot
What is the most common symptom associated with absent RCA?
- Wheeze
- Sudden death
- Asymptomatic
- Palpitations
- Shortness of breath
What is the approximate incidence of absent RCA in the general population?
- 0.025%
- 0.25%
- 25%
- 5%
- 25%
Answers – 1,3,2
Discussion
Congenital absence of the RCA is a very rare anatomical variant with an estimated incidence of 0.014%-0.066%.1Patients are usually asymptomatic and it is considered a benign pathology, although it can be associated with other cardiac abnormalities such as bicuspid aortic valve, coronary artery fistula and hypertrophic cardiomyopathy.2 None of these were present in this case. Two patterns have been described: L-I pattern where the RCA territory is supplied by an extension of the circumflex artery or LAD (as in this case), and L-II pattern where the RCA territory is supplied by a branch arising from proximal LCA. The L-I pattern appears to be slightly more common and demonstrates a slightly higher incidence of acute MI.3
Previously coronary angiography was considered the gold standard of imaging, however with advances in CTCA, imaging with both modalities is considered useful in giving the most robust assessment of the coronary arteries and their neighbouring structures.3
There is no defined guideline for treatment, which may consist of either conservative or interventional management depending on the severity of coronary atherosclerosis and stenosis. In this case, the symptoms were all felt to be related to the patient’s severe aortic valve disease and he is being worked up for a TAVI.
References:
- Zhu XY, Tang XH. Congenital absence of the right coronary artery: A case report. World J Clin Cases2022; 10(34): 12799-12803 [PMID: 36579109 DOI: 12998/wjcc.v10.i34.12799]
- Canan, A. and Batra, K., 2022. Superdominant Left Circumflex Artery with Absent Right Coronary Artery. Radiology, 304(2), pp.294-294.
- Chen Z, Yan J, Han X, Adhikari BK, Zhang J, Zhang Y, Sun J, Wang Y. Congenital absence of the right coronary artery with acute myocardial infarction: report of two cases and review of the literature. J Int Med Res. 2020 Dec;48(12):300060520971508. doi: 10.1177/0300060520971508. PMID: 33275472; PMCID: PMC7720338.