Introduction/Hypothesis:
Abstract
Coronary artery anomalies are uncommon, and often incidentally found. An interarterial course is considered malignant with a higher risk of ischemia and sudden cardiac death. Our case focuses on an interarterial right coronary artery originating from the left sinus of Valsalva in an older patient with vague symptoms. This was found incidentally on a coronary artery calcium CT scan, and then confirmed on a dedicated coronary CTA. The patient has since been asymptomatic without inducible ischemia on a nuclear myocardial stress test, and therefore is being managed conservatively. Due to the rarity of this anomaly, further data is needed to track outcomes and hopefully form more definitive guidelines.

Introduction
Coronary artery anomalies are congenital abnormalities where the left or right coronary artery has an abnormal origin, course and/or termination. Often, the anomalous artery originates from the opposite sinus of Valsalva. Coronary artery anomalies are uncommon, with a general population incidence of 0.2 to 1.2 % (1). Patient presentation can vary, though the vast majority of these anomalies are found incidentally in asymptomatic patients. Certain courses and features, however, can result in ischemia, arrhythmias, or sudden cardiac death, with symptomatic patients presenting at a younger age (2).
The four common courses described for anomalous coronary arteries are retroaortic, prepulmonic, transseptal, and interarterial. The interarterial course, where the anomalous coronary artery traverses between the ascending aorta and main pulmonary artery to perfuse its specific myocardial territory, is considered malignant and poses the highest risk of sudden cardiac death and/or ischemia. This case presentation focuses on an interarterial course of the right coronary artery (RCA) originating from the left sinus of Valsalva.

Methods
Case Presentation
A 70 year old male presented to his primary care physician with reported episodes of non-specific left sided chest pressure. An EKG was unremarkable and there were no relevant laboratory abnormalities. Given his past medical history of hyperlipidemia, hypertension, carotid artery stenosis, and elevated body mass index, a coronary artery calcium scoring CT without contrast was obtained. Results revealed a total Agatston score of 21, most notably involving the RCA (with a score of 20). Incidentally, an anomalous origin of the RCA from the left coronary cusp with an interarterial (malignant) course was suspected (Figure 1). Approximately 1 month later, a Coronary CT Angiogram without and with contrast exam (Coronary CTA) was obtained which confirmed the interarterial course of the RCA (Figures 2 and 3). A moderate degree of proximal RCA stenosis with high risk (previously vulnerable) plaque was also present. A nuclear myocardial exercise stress test was performed during which the patient remained asymptomatic and revealed no imaging findings to suggest ischemia or infarct. The patient followed up with Cardiology and is being managed conservatively. He has remained asymptomatic on continued follow up visits.

Results
Discussion
An anomalous right coronary artery (RCA) with an interarterial course is considered to be a high-risk lesion with further workup warranted due to the risk of ischemia and/or sudden cardiac death. Prognosis and treatment varies, with further management depending on several factors including clinical presentation, inducible ischemia on hemodynamic testing, the presence of coronary artery disease, as well as certain high-risk features.
Most patients with this anomaly remain asymptomatic, though a minority present with ischemia via chest pain or sudden cardiac death, though sudden cardiac death is more commonly associated with an interarterial left coronary artery (3). Mechanistically, this is due to compression of the artery by the ascending aorta and main pulmonary artery, usually during increased cardiac output states such as exercise (4). The anomalous coronary artery origin is often angled sharply with a slit like ostium; this may enable the artery to get stretched during exercise which narrows the origin resulting in ischemia (5).
Diagnostic image testing plays a crucial role in the workup and decision-making process in these patients. Due to recent technical advancements in Coronary CTA, notably regarding reduced radiation dose and improved spatial resolution, this has become a common first line modality in evaluation (6,7). It is great for general anatomic assessment, and can identify certain high risk features; these include an intramural course - where the artery travels through the tunica media of the ascending aortic wall, acute angle of the artery origin, and a slit-like orifice (5). Cardiac imagers should also take note of the height of the anomalous artery’s course in relation to the pulmonary valve; a high course (above the valve) is less favorable since it is more prone to compression by the aorta and pulmonary artery during systole, whereas a low course (below the valve) would traverse between the aorta and contracted right ventricular outflow tract (5,8). Nuclear cardiac imaging is of utility by revealing exercise induced ischemia, which can be particularly helpful in asymptomatic patients or patients with vague symptoms. Other modalities such as cardiac MRI and CTA-derived fractional flow reserve are reported in the literature to have been used, though are not commonplace. Cardiac MRI is appealing when radiation dose is of particular concern, such as in pediatric patients. It can also reveal myocardial fibrosis related to ischemia within the affected territory. CTA derived fractional flow reserve assesses the hemodynamic significance of coronary lesions, which can be of particular benefit in equivocal cases or asymptomatic patients (9).
Treatment for anomalous coronary arteries with an interarterial course originating from the opposite sinus of Valsalva varies and must be assessed on a case by case basis. The Journal of the American Heart Association’s most up to date proposed therapeutic management algorithm recommends hemodynamic assessment to guide management of patients with this lesion, that is after an interarterial course (and/or other high-risk features) is confirmed on Coronary CTA (10). If the hemodynamic assessment is negative and the patient remains asymptomatic, then no treatment or exercise restrictions are required; this is the case for our patient. If hemodynamic assessment is positive, then surgical management is recommended. With concomitant coronary artery disease, coronary artery bypass graft is proposed. Unroofing, neo-ostium/translocation, and patch angioplasty are options when coronary artery disease is not present; the choice of which varies based on anatomic features. Currently, most evidence for these management recommendations comes from small registries, case series and case reports. Therefore, accumulating further data from larger patient registries will hopefully continue to improve and standardize clinical decision making. This is relevant to consider because it would not be unreasonable to suspect that the absolute number and prevalence of this anomaly (and other coronary anomalies) will rise given the more widespread use of Coronary CTA (6).

Conclusion
Conclusion
An anomalous right coronary artery with an interarterial course originating from the left sinus of Valsalva is a rare congenital abnormality. Though often found incidentally, there is a risk of ischemia and sudden cardiac death. These, and other coronary artery anomalies, are very well appreciated and detailed on a Coronary CTA. The interarterial course, along with other high-risk features, is important for the cardiac imager to be aware of and document in the report. Clinical presentation and hemodynamic testing can help guide further therapeutic decision making, as detailed nicely in a recently proposed management algorithm by the Journal of the American Heart Association. However, more data is needed to continue to improve recommendations and possibly formulate more standardized guidelines. We should hope for this to occur with the more prevalent use of Coronary CTA and subsequent identification of this anomaly in the population.

References
Graidis C, Dimitriadis D, Karasavvidis V, et al. Prevalence and characteristics of coronary artery anomalies in an adult population undergoing multidetector-row computed tomography for the evaluation of coronary artery disease. BMC Cardiovasc Disord. 2015;15:112. Published 2015 Oct 2. doi:10.1186/s12872-015-0098-x
Taylor AJ, Rogan KM, Virmani R. Sudden cardiac death associated with isolated congenital coronary artery anomalies. J Am Coll Cardiol. 1992;20(3):640-647. doi:10.1016/0735-1097(92)90019-j
Gersony WM. Management of anomalous coronary artery from the contralateral coronary sinus. J Am Coll Cardiol. 2007;50(21):2083-2084. doi:10.1016/j.jacc.2007.08.023 10.1016/j.jacc.2007.08.023. Epub 2007 Nov 5. PMID: 18021878.
Angelini P. Coronary artery anomalies: an entity in search of an identity. Circulation. 2007;115(10):1296-1305. doi:10.1161/CIRCULATIONAHA.106.618082
Ferreira AFP, Rosemberg S, Oliveira DS, Araujo-Filho JAB, Nomura CH. Anomalous origin of coronary arteries with an interarterial course: pictorial essay. Radiol Bras. 2019;52(3):193-197. doi:10.1590/0100-3984.2017.0203
Ghadri JR, Kazakauskaite E, Braunschweig S, et al. Congenital coronary anomalies detected by coronary computed tomography compared to invasive coronary angiography. BMC Cardiovasc Disord. 2014;14:81. Published 2014 Jul 8. doi:10.1186/1471-2261-14-81
Gräni C, Benz DC, Schmied C, et al. Prevalence and characteristics of coronary artery anomalies detected by coronary computed tomography angiography in 5 634 consecutive patients in a single centre in Switzerland. Swiss Med Wkly. 2016;146:w14294. Published 2016 Apr 28. doi:10.4414/smw.2016.14294
Lee HJ, Hong YJ, Kim HY, et al. Anomalous origin of the right coronary artery from the left coronary sinus with an interarterial course: subtypes and clinical importance. Radiology. 2012;262(1):101-108. doi:10.1148/radiol.11110823
Nørgaard BL, Leipsic J, Gaur S, et al. Diagnostic performance of noninvasive fractional flow reserve derived from coronary computed tomography angiography in suspected coronary artery disease: the NXT trial (Analysis of Coronary Blood Flow Using CT Angiography: Next Steps). J Am Coll Cardiol. 2014;63(12):1145-1155. doi:10.1016/j.jacc.2013.11.043
Bigler, Marius Reto, et al. “Therapeutic Management of Anomalous Coronary Arteries Originating from the Opposite Sinus of Valsalva: Current Evidence, Proposed Approach, and the Unknowing.” Journal of the American Heart Association, vol. 11, no. 20, 18 Oct. 2022, https://doi.org/10.1161/jaha.122.027098.

**Introduction/Hypothesis:**
Abstract
Coronary artery anomalies are uncommon, and often incidentally found. An interarterial course is considered malignant with a higher risk of ischemia and sudden cardiac death. Our case focuses on an interarterial right coronary artery originating from the left sinus of Valsalva in an older patient with vague symptoms. This was found incidentally on a coronary artery calcium CT scan, and then confirmed on a dedicated coronary CTA. The patient has since been asymptomatic without inducible ischemia on a nuclear myocardial stress test, and therefore is being managed conservatively. Due to the rarity of this anomaly, further data is needed to track outcomes and hopefully form more definitive guidelines.

Introduction
Coronary artery anomalies are congenital abnormalities where the left or right coronary artery has an abnormal origin, course and/or termination. Often, the anomalous artery originates from the opposite sinus of Valsalva. Coronary artery anomalies are uncommon, with a general population incidence of 0.2 to 1.2 % (1). Patient presentation can vary, though the vast majority of these anomalies are found incidentally in asymptomatic patients. Certain courses and features, however, can result in ischemia, arrhythmias, or sudden cardiac death, with symptomatic patients presenting at a younger age (2).
The four common courses described for anomalous coronary arteries are retroaortic, prepulmonic, transseptal, and interarterial. The interarterial course, where the anomalous coronary artery traverses between the ascending aorta and main pulmonary artery to perfuse its specific myocardial territory, is considered malignant and poses the highest risk of sudden cardiac death and/or ischemia. This case presentation focuses on an interarterial course of the right coronary artery (RCA) originating from the left sinus of Valsalva.

**Methods**
Case Presentation
A 70 year old male presented to his primary care physician with reported episodes of non-specific left sided chest pressure. An EKG was unremarkable and there were no relevant laboratory abnormalities. Given his past medical history of hyperlipidemia, hypertension, carotid artery stenosis, and elevated body mass index, a coronary artery calcium scoring CT without contrast was obtained. Results revealed a total Agatston score of 21, most notably involving the RCA (with a score of 20). Incidentally, an anomalous origin of the RCA from the left coronary cusp with an interarterial (malignant) course was suspected (Figure 1). Approximately 1 month later, a Coronary CT Angiogram without and with contrast exam (Coronary CTA) was obtained which confirmed the interarterial course of the RCA (Figures 2 and 3). A moderate degree of proximal RCA stenosis with high risk (previously vulnerable) plaque was also present. A nuclear myocardial exercise stress test was performed during which the patient remained asymptomatic and revealed no imaging findings to suggest ischemia or infarct. The patient followed up with Cardiology and is being managed conservatively. He has remained asymptomatic on continued follow up visits.

**Results**
Discussion
An anomalous right coronary artery (RCA) with an interarterial course is considered to be a high-risk lesion with further workup warranted due to the risk of ischemia and/or sudden cardiac death. Prognosis and treatment varies, with further management depending on several factors including clinical presentation, inducible ischemia on hemodynamic testing, the presence of coronary artery disease, as well as certain high-risk features.
Most patients with this anomaly remain asymptomatic, though a minority present with ischemia via chest pain or sudden cardiac death, though sudden cardiac death is more commonly associated with an interarterial left coronary artery (3). Mechanistically, this is due to compression of the artery by the ascending aorta and main pulmonary artery, usually during increased cardiac output states such as exercise (4). The anomalous coronary artery origin is often angled sharply with a slit like ostium; this may enable the artery to get stretched during exercise which narrows the origin resulting in ischemia (5).
Diagnostic image testing plays a crucial role in the workup and decision-making process in these patients. Due to recent technical advancements in Coronary CTA, notably regarding reduced radiation dose and improved spatial resolution, this has become a common first line modality in evaluation (6,7). It is great for general anatomic assessment, and can identify certain high risk features; these include an intramural course - where the artery travels through the tunica media of the ascending aortic wall, acute angle of the artery origin, and a slit-like orifice (5). Cardiac imagers should also take note of the height of the anomalous artery’s course in relation to the pulmonary valve; a high course (above the valve) is less favorable since it is more prone to compression by the aorta and pulmonary artery during systole, whereas a low course (below the valve) would traverse between the aorta and contracted right ventricular outflow tract (5,8). Nuclear cardiac imaging is of utility by revealing exercise induced ischemia, which can be particularly helpful in asymptomatic patients or patients with vague symptoms. Other modalities such as cardiac MRI and CTA-derived fractional flow reserve are reported in the literature to have been used, though are not commonplace. Cardiac MRI is appealing when radiation dose is of particular concern, such as in pediatric patients. It can also reveal myocardial fibrosis related to ischemia within the affected territory. CTA derived fractional flow reserve assesses the hemodynamic significance of coronary lesions, which can be of particular benefit in equivocal cases or asymptomatic patients (9).
Treatment for anomalous coronary arteries with an interarterial course originating from the opposite sinus of Valsalva varies and must be assessed on a case by case basis. The Journal of the American Heart Association’s most up to date proposed therapeutic management algorithm recommends hemodynamic assessment to guide management of patients with this lesion, that is after an interarterial course (and/or other high-risk features) is confirmed on Coronary CTA (10). If the hemodynamic assessment is negative and the patient remains asymptomatic, then no treatment or exercise restrictions are required; this is the case for our patient. If hemodynamic assessment is positive, then surgical management is recommended. With concomitant coronary artery disease, coronary artery bypass graft is proposed. Unroofing, neo-ostium/translocation, and patch angioplasty are options when coronary artery disease is not present; the choice of which varies based on anatomic features. Currently, most evidence for these management recommendations comes from small registries, case series and case reports. Therefore, accumulating further data from larger patient registries will hopefully continue to improve and standardize clinical decision making. This is relevant to consider because it would not be unreasonable to suspect that the absolute number and prevalence of this anomaly (and other coronary anomalies) will rise given the more widespread use of Coronary CTA (6).

**Conclusion**
Conclusion
An anomalous right coronary artery with an interarterial course originating from the left sinus of Valsalva is a rare congenital abnormality. Though often found incidentally, there is a risk of ischemia and sudden cardiac death. These, and other coronary artery anomalies, are very well appreciated and detailed on a Coronary CTA. The interarterial course, along with other high-risk features, is important for the cardiac imager to be aware of and document in the report. Clinical presentation and hemodynamic testing can help guide further therapeutic decision making, as detailed nicely in a recently proposed management algorithm by the Journal of the American Heart Association. However, more data is needed to continue to improve recommendations and possibly formulate more standardized guidelines. We should hope for this to occur with the more prevalent use of Coronary CTA and subsequent identification of this anomaly in the population.

References
1. Graidis C, Dimitriadis D, Karasavvidis V, et al. Prevalence and characteristics of coronary artery anomalies in an adult population undergoing multidetector-row computed tomography for the evaluation of coronary artery disease. _BMC Cardiovasc Disord_. 2015;15:112. Published 2015 Oct 2. doi:10.1186/s12872-015-0098-x
2. Taylor AJ, Rogan KM, Virmani R. Sudden cardiac death associated with isolated congenital coronary artery anomalies. _J Am Coll Cardiol_. 1992;20(3):640-647. doi:10.1016/0735-1097(92)90019-j
3. Gersony WM. Management of anomalous coronary artery from the contralateral coronary sinus. _J Am Coll Cardiol_. 2007;50(21):2083-2084. doi:10.1016/j.jacc.2007.08.023 10.1016/j.jacc.2007.08.023. Epub 2007 Nov 5. PMID: 18021878.
4. Angelini P. Coronary artery anomalies: an entity in search of an identity. _Circulation_. 2007;115(10):1296-1305. doi:10.1161/CIRCULATIONAHA.106.618082
5. Ferreira AFP, Rosemberg S, Oliveira DS, Araujo-Filho JAB, Nomura CH. Anomalous origin of coronary arteries with an interarterial course: pictorial essay. _Radiol Bras_. 2019;52(3):193-197. doi:10.1590/0100-3984.2017.0203
6. Ghadri JR, Kazakauskaite E, Braunschweig S, et al. Congenital coronary anomalies detected by coronary computed tomography compared to invasive coronary angiography. _BMC Cardiovasc Disord_. 2014;14:81. Published 2014 Jul 8. doi:10.1186/1471-2261-14-81
7. Gräni C, Benz DC, Schmied C, et al. Prevalence and characteristics of coronary artery anomalies detected by coronary computed tomography angiography in 5 634 consecutive patients in a single centre in Switzerland. _Swiss Med Wkly_. 2016;146:w14294. Published 2016 Apr 28. doi:10.4414/smw.2016.14294
8. Lee HJ, Hong YJ, Kim HY, et al. Anomalous origin of the right coronary artery from the left coronary sinus with an interarterial course: subtypes and clinical importance. _Radiology_. 2012;262(1):101-108. doi:10.1148/radiol.11110823
9. Nørgaard BL, Leipsic J, Gaur S, et al. Diagnostic performance of noninvasive fractional flow reserve derived from coronary computed tomography angiography in suspected coronary artery disease: the NXT trial (Analysis of Coronary Blood Flow Using CT Angiography: Next Steps). _J Am Coll Cardiol_. 2014;63(12):1145-1155. doi:10.1016/j.jacc.2013.11.043
10. Bigler, Marius Reto, et al. “Therapeutic Management of Anomalous Coronary Arteries Originating from the Opposite Sinus of Valsalva: Current Evidence, Proposed Approach, and the Unknowing.” Journal of the American Heart Association, vol. 11, no. 20, 18 Oct. 2022, https://doi.org/10.1161/jaha.122.027098.

Case Report of an Interarterial Right Coronary Artery: Imaging Features, Work-Up, and Management 

This course will explore basic and cutting-edge imaging techniques to improve patient care and hone individual skills in performance and interpretation of echocardiography, nuclear cardiology, cardiac computed tomography, and cardiovascular magnetic resonance imaging. Days will reinforce how cardiovascular imaging may improve comprehension in ischemic heart disease, structural heart disease, cardiomyopathies, and heart failure. Experts will utilize novel techniques to reinforce key topics including taped interventional cases and a strong emphasis on case presentations.