Abstract
Background
Anomalous coronary artery from the opposite sinus is a rare congenital anomaly with potentially fatal outcomes. Anomalous right coronary artery (ARCA) with a malignant interarterial course is strongly linked to sudden cardiac death Beyond description of anatomy, optimal management requires careful diagnostic evaluation and individualized decision-making.
Cases
We present 3 cases of ARCA with malignant interarterial course: 1) an 80-year-old man with severe aortic stenosis, 2) a 61-year-old woman with exertional angina and interarterial narrowing, and 3) a 25-year-old asymptomatic woman with ventricular ectopy and significant proximal narrowing. Each case highlights unique diagnostic challenges and therapeutic considerations.
Discussion
Coronary computed tomography angiography is the gold standard for defining anatomy, whereas functional testing, cardiac magnetic resonance, and invasive imaging refine risk stratification. Management ranges from surveillance with lifestyle modification in low-risk, asymptomatic patients to surgical correction (unroofing, reimplantation, or coronary artery bypass grafting) in young or high-risk individuals. We summarize these principles in a practical flowchart to guide clinicians.
Conclusions
Early recognition, structured diagnostic work-up, and risk-based individualized management are essential to prevent adverse outcomes in ARCA. This case series provides both illustrative clinical examples and an evidence-based framework for evaluation and management.
Key words: ACAOS, anomalous right coronary artery, aortic stenosis, coronary CT angiography, malignant interarterial course, reimplantation, sudden cardiac death, unroofing procedure
Visual Summary
Congenital anomalies of origin of coronary arteries are rare, with an incidence from 0.24% to 1.3% of cases.1 Anomalous coronary artery from the opposite sinus (ACAOS) is a rare entity, with a reported incidence of 1.3% in patients undergoing coronary angiography at the Cleveland Clinic Foundation from 1960 to 1988. Coronary artery anomalies (CAAs) include several congenital conditions characterized by abnormal origin or course of any of the 3 main epicardial coronary arteries. Because of the existence of many possible interindividual normal anatomic variants, the term CAA has historically been restricted to those occurring in <1% of the general population.2 The prognostic implications of CAAs in this setting remain poorly understood, and guideline-recommended therapeutic decisions are supported by a low level of scientific evidence. Management of asymptomatic patients with CAAs may be challenging, particularly in younger individuals. CAAs have been associated with sudden cardiac death (SCD), especially in young individuals engaged in sports.
Most CAAs originate in the left main coronary artery or left anterior descending artery from the right coronary sinus.2 These anomalies are often asymptomatic, being detected incidentally during cardiac catheterization. Studies have shown that 81% of these anomalies are benign, whereas the remaining 19% involve more dangerous anomalies such as ectopic origin from the pulmonary artery, opposite aortic sinus, single coronary artery, and large coronary fistulas, all of which are associated with profound clinical consequences.3,4 ACAOS is a known cause of SCD in young patients, contributing to approximately one-third of such cases, particularly in athletes, with the anomalous right coronary artery (ARCA) being the most common culprit.5 Recent guidelines from the American Heart Association and American College of Cardiology on management of adults with congenital heart disease have highlighted that am anomalous coronary artery origin with subsequent malignant course (ie, the course of the artery is between the aorta and pulmonary trunk) can lead to myocardial ischemia, arrhythmia, or SCD.
Anomalous origin of the right coronary artery (RCA) is a rare congenital abnormality first described by White and Edward in 1948.6 ARCA is particularly dangerous when it takes a high interarterial course between the ascending aorta and pulmonary artery, which is linked to SCD in a substantial number of cases. Mortality rates for ARCA are lower than for anomalous left coronary artery, but they are still considerable, especially in young, symptomatic individuals.7 Early detection through imaging and timely intervention are crucial to prevent catastrophic outcomes.
Case 1
An 80-year-old man presented with progressively worsening exertional dyspnea and fatigue over the past 6 months, significantly affecting his daily activities. His medical history was notable for the absence of prior cardiac events. On examination, a harsh, late-peaking systolic murmur was detected at the right upper sternal border, radiating to the carotids, raising strong clinical suspicion for severe aortic stenosis. Transthoracic echocardiography confirmed the diagnosis, revealing severe calcific degenerative aortic stenosis with an aortic valve area of 0.7 cm2, a peak transvalvular velocity of 4.5 m/s, and a mean gradient of 60 mm Hg.
Take-Home Messages
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Anomalous right coronary artery with malignant interarterial course is a rare but potentially fatal condition that requires high clinical suspicion and multimodality imaging for diagnosis.
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Risk stratification based on anatomic features and functional assessment is essential to guide therapy.
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Early recognition and individualized management—ranging from surveillance to surgery—can prevent adverse outcomes, including sudden cardiac death.
As part of the preoperative evaluation for transcatheter aortic valve replacement, a coronary computed tomography angiogram (CCTA) was performed to assess coronary anatomy. This revealed a dominant RCA with an anomalous origin from the left coronary sinus, arising close to the left main coronary artery. The RCA followed a malignant interarterial course, passing acutely between the pulmonary trunk and the ascending aorta. The proximal segment of the RCA was significantly narrowed and slit-like over a length of 1.6 cm (Figure 1), likely due to extrinsic compression from the great vessels during systolic expansion. This anatomic anomaly is associated with a high risk of myocardial ischemia and SCD, further compounding the patient's clinical risk.
Figure 1.
CCTA of Case 1 Showing Anomalous RCA With Slit-Like Proximal Segment
(A) Computed tomography 3-dimensional reconstruction showing both the left main artery and RCA originating from the left coronary cusp. (B) Computed tomography angiography showing degenerative sclerosis calcified aortic valve. (C) Computed tomography angiography showing the RCA originating from the LCC with an interarterial course, a slit-like orifice, and minimal intramural segment. LCC = left coronary cusp; RCA = right coronary artery.
Given the severity of the aortic stenosis and the high-risk coronary anatomy, the patient was deemed an appropriate candidate for transcatheter aortic valve implantation. He underwent transcatheter aortic valve implantation with a balloon-expandable Myril 26-mm valve. The procedure was uneventful, with successful implantation confirmed by postprocedural imaging and significant improvement in hemodynamic parameters. The patient recovered well without complications such as conduction abnormalities or paravalvular leak. On the third postoperative day, he was discharged home in stable condition, with notable symptomatic relief and a plan for continued follow-up.
This case highlights the critical role of detailed preoperative imaging and multidisciplinary management in patients with dual pathologies like severe aortic stenosis and coronary anomalies, ensuring optimal outcomes.
Case 2
A 61-year-old woman presented with intermittent left-sided chest pain and dyspnea on exertion, which had been recurring over the past year. She denied syncope or palpitations but described her symptoms as exertional and self-resolving with rest.
The patient had no significant history of coronary artery disease, hypertension, or diabetes. Given her symptoms suggestive of ischemia, a CCTA was performed. The imaging revealed a dominant RCA with an anomalous origin from the left coronary cusp, arising at an acute angle. The proximal RCA exhibited an interarterial course, passing between the pulmonary trunk anteriorly and the ascending aorta posteriorly (Figure 2).
Figure 2.
3D CT of Case 2 Showing RCA Origin From LCC With Interarterial Course
(A and B) Computed tomography 3-dimensional reconstruction showing both the LM and RCA originating from the left coronary cusp. (C) Computed tomography angiography showing the RCA originating from the LCC with an interarterial course, a slit-like orifice, and minimal intramural segment. LCC = left coronary cusp; LM = left main; RCA = right coronary artery.
The interarterial segment of the RCA demonstrated mild narrowing, attributed to extrinsic compression between the great vessels. No significant atherosclerotic plaques or luminal stenosis were identified elsewhere in the coronary arteries. These findings were consistent with a malignant course of the anomalous RCA, a configuration that can predispose to myocardial ischemia due to transient luminal compression during increased cardiac output.
Despite the absence of significant atherosclerosis, the patient's clinical presentation and anatomic findings raised concerns about potential ischemia, especially during periods of exertion or stress. Further functional assessment and multidisciplinary evaluation were planned to guide therapeutic decisions.
Case 3
A 25-year-old woman presented for routine medical fitness evaluation. She was asymptomatic, with no history of chest pain, syncope, or palpitations. Her physical examination was unremarkable, and vital signs were stable.
A standard 12-lead electrocardiogram revealed frequent multifocal ventricular premature complexes. To further evaluate the arrhythmia, 48-hour Holter monitoring was performed, which showed isolated ectopic beats without any episodes of sustained arrhythmia (Figure 3).
Figure 3.
Holter: Predominant Underlying Rhythm Was Sinus Rhythm
Multifocal PVCs noted. The average heart rate was 79 beats/min. The minimum heart rate was 59 beats/min. The maximum heart rate was 133 beats/min. Ventricular ectopy was 49,623, with 49,469 isolated VE, 56 V-pairs, 14 V-triplets, and 0 V-runs. Ventricular bigeminy events were 350, and ventricular trigeminy events were 3,200. Supraventricular ectopy was 0, with 0 isolated SVE, 0 SV-pairs, 0 SV-triplets, and 0 SV-runs. Supraventricular bigeminy events were 0, and supraventricular trigeminy events were 0. Pauses >2.2 seconds were 0. The longest RR was 1.4 seconds. HR = heart rate; PVC = premature ventricular contraction; RR = R-R interval; SV = supraventricular; VE = ventricular ectopy.
Subsequently, CCTA was conducted to rule out structural anomalies. CCTA demonstrated an anomalous origin of the RCA from the left coronary sinus, arising close to the left main coronary artery. The RCA exhibited a malignant course, passing at an acute angle between the ascending aorta and pulmonary trunk. The proximal segment of the RCA was significantly narrowed, measuring approximately 1.4 cm in length. No evidence of atherosclerotic plaques or additional coronary anomalies was noted (Figure 4).
Figure 4.
CCTA of Case 3 Showing Malignant RCA Course With Narrowing
(A and B) Computed tomography 3-dimensional reconstruction showing both the LM and RCA originating from the left coronary cusp. (C) Computed tomography angiography showed the RCA originating from the LCC with an interarterial course and minimal intramural segment. LCC = left coronary cusp; and other abbreviations as in Figure 2.
Discussion
CAAs can be classified into 5 broad categories.
Anatomic classification includes subcategories based on origin, course, and termination. Anomalies of origin involve situations like an anomalous coronary artery originating from the opposite sinus of Valsalva, high takeoff origin, or origin from a noncoronary sinus or other cardiac structures. Abnormal courses include interarterial, intramural, subendocardial, retroaortic, or prepulmonic. Abnormal terminations include coronary fistulas or coronary cameral communications. Functional classification categorizes anomalies as benign, where they have no hemodynamic significance or clinical symptoms, or malignant, where they are associated with ischemia, SCD, or other complications, such as an interarterial course. Clinical classification distinguishes isolated anomalies, which occur without associated congenital heart defects, from anomalies associated with structural heart diseases, such as Tetralogy of Fallot. Hemodynamic classification divides anomalies into those that are hemodynamically significant, leading to ischemia or obstruction, and those that are hemodynamically insignificant, with no functional impact. Embryologic classification is based on disrupted coronary artery development, such as abnormal septation of the truncus arteriosus or failure of coronary buds to form or connect to the aortic sinuses. This classification aids in evaluating clinical relevance, guiding diagnosis, and informing treatment strategies.
Anomalous RCAs that originate from the left coronary sinus occur in 0.05% to 0.1% of the general population.8 Anomalous coronary arteries, including ARCA, are rare but clinically significant anomalies. As noted in several studies, these anomalies often lead to myocardial ischemia due to the atypical course of the coronary artery, which can lead to mechanical compression or even occlusion.9 In ARCA, the abnormal course can lead to a situation where the artery is compressed between the aorta and pulmonary artery, especially during periods of increased cardiac output, such as during exercise.10 This results in transient ischemia, which can precipitate malignant arrhythmias and SCD.
Myocardial ischemia is considered the primary cause of life-threatening events in patients with CAAs. The most commonly proposed are ostial stenosis, caused by acute take-off angle or compression of the intramural segment by the aortic valve commissure, and mechanical compression during exercise, which increases the risk of ischemia, especially if the artery follows a high interarterial course. They are consistently associated with SCD in young athletes. From a pathophysiological standpoint, the possible compression of the anomalous coronary between the great vessels was first proposed as a causative mechanism of ischemia and hence SCD. However, such a compressive effect from a low-pressure vessel such as the pulmonary artery seems unlikely in the absence of significant pulmonary hypertension. Conversely, the vigorous systolic expansion of the aorta may cause kinking or precipitate a coronary spasm, and the presence of a slit-like ostium may facilitate intermittent vessel occlusion. Vasospasm of the anomalous artery has also been implicated in causing ischemic events. Angelini2 proposed an alternative explanation: the existence and specific features of an initial intramural course may be pivotal in the pathogenesis of myocardial ischemia in patients with malignant CAAs. Indeed, although such tracts may often be hypoplastic compared with the distal vessel, various degrees of lateral compression secondary to the shear stress exerted by the aortic walls may precipitate ischemia during systole and the initial diastole, particularly in the presence of increased aortic stiffness.
In summary, when current knowledge and persisting uncertainties are balanced, myocardial ischemia remains the most likely mechanism of SCD in patients with CAAs. Although the real impact of ischemia on the absolute risk of cardiovascular events remains to be clarified, it seems reasonable to consider the presence of inducible ischemia as a potential predictor of life-threatening events. Conversely, whether the absence of inducible myocardial ischemia could be considered a reassuring sign in this context is unknown and requires further study.
In the first case, the ischemic threshold may have been surpassed by the combined effect of aging and calcific aortic stenosis, which likely contributed to the severity of symptoms. In the second case, although there was mild narrowing at the interarterial segment, the absence of significant atherosclerotic plaque suggests that the ischemic events were primarily due to the anomalous course of the RCA. In the third case, the young patient presented with asymptomatic ventricular ectopy and a high-risk anatomic anomaly. Although she was asymptomatic, the presence of significant narrowing and ectopy warrants close monitoring and a multidisciplinary discussion to evaluate the need for surgical correction. Conservative management, including exercise restriction, may be an initial approach, but functional studies would be pivotal in guiding long-term management.
CCTA is the gold standard for diagnosing ACAOS due to its high spatial resolution, which allows for detailed imaging of coronary anatomy and course. CCTA provides multiplanar reconstruction images that are invaluable in detecting and characterizing coronary anomalies. For high-risk cases, additional imaging such as cardiac magnetic resonance or intravascular ultrasound may be used to assess functional significance and guide management decisions.
The management of patients with ACAOS depends on the course and symptoms. Although many cases of ARCA are benign, patients with high interarterial courses are at increased risk of adverse events, including SCD. Surgical interventions such as reimplantation of the anomalous artery or coronary artery bypass grafting are considered in high-risk patients, particularly those who are symptomatic or <35 years of age. For asymptomatic older patients, conservative management with exercise limitation may be sufficient. The Japanese approach to this condition is far more conservative, as demonstrated by a study of 56 patients who had anomalous arteries and were treated medically with beta-blockers. Side effects of the conservative approach included hypotension and arrhythmias on exertion (9%). No deaths had occurred at a 5-year analysis of the study.
Recent studies suggest that unroofing the intramural segment of the anomalous artery can reduce lateral compression, thus improving blood flow and alleviating symptoms. However, complications such as aortic valve incompetence may arise, which should be considered during surgical planning.
Building on the case-specific insights and existing literature, it is essential to summarize the practical approach to diagnostic evaluation and management strategies for ARCA with malignant course.
Diagnostic Work-Up and Management Approaches
Evaluation of ARCA with malignant course requires multimodality imaging. CCTA remains the gold standard for defining origin, course, and high-risk features such as slit-like ostium or intramural segment. Electrocardiogram/Holter monitoring may reveal arrhythmias, whereas stress testing or cardiac magnetic resonance helps detect inducible ischemia. In select cases, intravascular ultrasound/fractional flow reserve further clarifies functional significance.
Management is individualized. Conservative therapy (exercise restriction, beta-blockers, or surveillance) is reasonable in asymptomatic low-risk patients. Surgical correction (unroofing, reimplantation, or coronary artery bypass grafting) is recommended in symptomatic individuals, young athletes, or those with high-risk anatomy/ischemia. Each option has trade-offs—medical therapy avoids operative risks but does not eliminate SCD risk, whereas surgery offers definitive correction but carries procedural morbidity. Decisions should involve a multidisciplinary team and shared discussion with patients.
To synthesize these principles, we provide a structured flowchart that summarizes the stepwise diagnostic evaluation, key risk stratification factors, and management pathways for patients with ARCA. This visual framework is intended to serve as a practical guide for clinicians and trainees encountering ACAOS in clinical practice. A practical diagnostic and management pathway for ARCA is illustrated in Figure 5.
Figure 5.
Flowchart: Evaluation and Management Pathway for Suspected ARCA
Work-up includes ECG, Holter, echocardiography, and CCTA. Risk is based on anatomy, ischemia, and symptoms, guiding conservative therapy, MDT review, or surgery. ARCA = anomalous right coronary artery; CABG = coronary artery bypass grafting; CCTA = coronary computed tomography angiography; CMR = cardiac magnetic resonance; ECG = electrocardiogram; FFR = fractional flow reserve; iFR = instantaneous wave-free ratio; IVUS = intravascular ultrasound; OCT = optical coherence tomography; MDT = multidisciplinary team.
Conclusions
ACAOS, particularly ARCA with malignant interarterial course, remains a rare but potentially life-threatening condition. With the growing use of CCTA, more cases will be identified, making structured diagnostic work-up and risk-based management increasingly important. Our series emphasizes that beyond describing anatomy, careful evaluation of high-risk features, functional assessment, and individualized treatment planning are essential to guide outcomes. Incorporation of a practical flowchart provides a concise, evidence-based framework that can support clinicians in decision-making and enhance patient safety.
Funding Support and Author Disclosures
The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
Footnotes
The authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the Author Center.
Appendix
Visual Summary.
| Case 1: 80-Year-Old Man | Case 2: 61-Year-Old Woman | Case 3: 25-Year-Old Woman | |
|---|---|---|---|
| Clinical presentation | Exertional dyspnea and fatigue. Examination suggestive of severe aortic stenosis. | Intermittent exertional chest pain and dyspnea. No known CAD. | Asymptomatic; incidental multifocal VPCs on routine ECG. |
| Echocardiography/Holter | Echo: severe calcific aortic stenosis (AVA: 0.7 cm2, MG: 60 mm Hg). | Echo: no major structural abnormalities. | Holter: Frequent multifocal VPCs (49,469 isolated VE, no sustained arrhythmias). |
| Coronary computed tomography angiography | RCA originating from left coronary sinus; malignant interarterial course; slit-like ostium; 1.6-cm proximal narrowing. | RCA from left coronary cusp; interarterial course with mild dynamic compression; acute take-off angle; no plaques. | RCA originating from left coronary sinus; malignant course; 1.4-cm proximal narrowing; no plaque. |
| Further evaluation | High-risk anatomy with severe AS → MDT decision for valve intervention first. | Considered for functional ischemia assessment and MDT discussion. | MDT discussion for risk stratification and possible functional testing. |
| Management/intervention | Underwent successful TAVI with 26-mm balloon-expandable valve. No complications; good hemodynamic improvement. | Conservative management planned; monitoring + ischemia testing. | Conservative vs surgical strategy discussed; initial surveillance recommended. |
| Follow-up | Significant symptomatic improvement; stable post-TAVI. | Symptom improvement; stable, no events. | Asymptomatic; stable arrhythmia burden; continued follow-up advised. |
Appendix
CCTA – Case 1: Anomalous RCA With Malignant Interarterial Course.
CCTA – Case 2: Interarterial RCA With Proximal Narrowing.
CCTA – Case 3: Slit-Like Ostium and Minimal Intramural Segment.
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Associated Data
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Supplementary Materials
CCTA – Case 1: Anomalous RCA With Malignant Interarterial Course.
CCTA – Case 2: Interarterial RCA With Proximal Narrowing.
CCTA – Case 3: Slit-Like Ostium and Minimal Intramural Segment.