Congenital absence of the right coronary artery (RCA) is an extremely rare coronary anomaly, but can have significant clinical implications. Therefore, early detection, correct diagnosis, and appropriate treatment are important. We present a unique case of a 19-year-old female presenting with chief complaints of chest pain and breathlessness. CT coronary angiography findings typically demonstrate single common origin of coronary artery from the left coronary sinus with no separate origin of RCA with left circumflex artery being dominant and supplying the RCA territory.
Congenital absence of the right coronary artery (RCA) is an extremely rare congenital anomaly of the cardiovascular system with an incidence of less than 0.066%. [1] It is considered as a benign anomaly, however, in certain cases, these patients may develop life-threatening clinical complications that include acute myocardial infarction, arrhythmia, stroke, or sudden cardiac death. [2 – 4]
Here, we present a clinical case of a patient found to have single coronary syndrome with congenital absence of the right coronary artery in a 19-year-old female presenting with chest pain and breathlessness along with a comprehensive radiological description. This case highlights the importance of recognizing and understanding such rare anatomical variations to guide appropriate clinical management. Congenital coronary artery anomalies, including single coronary syndrome, are thought to arise from disturbances during embryogenesis. While the exact etiology remains unknown, proposed theories include agenesis or congenital occlusion of the RCA during the embryonic period which may also have an association with other congenital heart disease (CHD) [ 5, 6]
Congenital absence of the right coronary artery (RCA) may be isolated or accompanied by other congenital abnormalities such as left coronary arterial dominance, absent left main coronary artery, bicuspid aortic valve, coronary artery fistula, and hyper-trophic cardiomyopathy. [7]
Clinical presentation of single coronary syndrome varies widely, ranging from asymptomatic individuals to those with ischemic symptoms related to concurrent coronary atherosclerosis or inter-arterial course. [8]
Diagnostic modalities such as invasive coronary angiography, CT coronary angiography, cardiac CT or cardiac MRI play crucial roles in confirming the diagnosis and delineating associated abnormalities.
A 19-year-old woman presented to the emergency department with complaints of substernal chest pain and shortness of breath. The symptoms had been occurring intermittently over the past few weeks, with an increase in frequency and severity over the past few days. The chest pain was described as a dull, pressure-like sensation, not radiating, and not associated with exertion, food intake, or position changes. There was no history of similar episodes in the past. The patient's vital signs were as follows: blood pressure 118/70 mmHg, heart rate 88 bpm, respiratory rate 16 breaths per minute, temperature 98.6°F (37°C), and oxygen saturation 97% on room air. Physical examination revealed a well-appearing young woman in no acute distress, with normal cardiovascular and respiratory findings, no abdominal tenderness, and no peripheral edema. Laboratory work-up was unremarkable, including a normal troponin I level, a complete blood count, and a basic metabolic panel within normal limits, with a negative D-dimer.
A resting electrocardiogram showed normal sinus rhythm without ST-T changes, and a chest X-ray revealed no acute cardiopulmonary findings. The exercise stress test was positive for myocardial ischemia, with the patient developing chest pain and ST segment abnormalities during the test. A coronary computed tomography angiogram (CTA) revealed the absence of the right coronary artery (RCA) and a dominant left circumflex artery (LCx) supplying the entire RCA territory.
Figure 1: CT angiography showing three coronary cusps LCC (Left coronary cusp), RCC (Right coronary cusp) and NCC (Non coronary cusp). The red star denotes no origin of the right coronary artery from RCC.
Figure 3: CT angiography showing empty right anterior atrioventricular groove (parallel red lines).
Figure 4: CT angiography showing the absence of a right coronary artery with the left circumflex supplying the distribution normally supplied by a native right coronary artery (yellow arrow) making it a left-dominant circulatory system.
Figure 5: VRT and MIP images are showing the Left main coronary artery (Green arrow) giving off the left anterior descending artery (purple arrow) and its branches marked D (Diagonal) and the Left Circumflex artery (blue arrow) with its branches marked OM (Obtuse marginal).
The absence of the right coronary artery is a rare congenital coronary anomaly. It may be asymptomatic but can present with symptoms of myocardial ischemia, particularly if collateral circulation is inadequate or if the increased demand during exercise cannot be met. In this patient, the positive exercise stress test indicated myocardial ischemia, likely due to the abnormal distribution of coronary blood flow. The management of this condition depends on the severity of symptoms and associated ischemia. Options may include medical management with anti-anginal medications, lifestyle modifications, and possibly interventional procedures or surgery if indicated by further assessment of myocardial perfusion and risk stratification.
This case highlights the importance of considering congenital coronary anomalies in young patients presenting with unexplained chest pain and shortness of breath. Advanced imaging techniques like coronary CTA play a crucial role in identifying these anomalies, guiding appropriate management, and improving patient outcomes.