**Introduction/Hypothesis:**
The incidence of anomalous right coronary artery (RCA) arising from the left coronary cusp is 0.92%.1,2,3 Patients are typically asymptomatic, however depending on the orifice characteristics and the anatomical course of the anomalous coronary artery it carries an increased risk for sudden cardiac death. Given the rarity of anomalous RCA and the typically asymptomatic course for the patients, procedural management is typically reserved for patients with high-risk anatomical features, concomitant coronary artery disease (CAD), and ischemia on functional imaging.4 We present a case of a 76-year-old male who presented with non-ST elevation myocardial infarction (NSTEMI) secondary to clinically significant CAD and was later found to have an anomalous RCA originating from the left coronary cusp with several high-risk anatomical features.

**Methods**
A 76-year-old male with a past history of systemic hypertension, chronic kidney disease and ischemic stroke who presented with cardiac chest pain. The patient’s chest pain occurred at rest, and he also endorsed associated diaphoresis and palpitations. In the emergency department, his troponins had dynamic rise, rising from 11 ng/L to 136 ng/L. His electrocardiogram on admission did not demonstrate signs of ischemia, however the following day exhibited T-wave inversions in the inferior leads. A transthoracic echocardiogram revealed no regional wall abnormalities with a left ventricular ejection fraction of 63%. He then underwent invasive coronary angiography (ICA), which demonstrated a normal anatomic origin of the left coronary arterial system from the left coronary cusp (Figure 1, Panel A), however, the right coronary ostium could not be identified by non-selective aortogram (Figure 1, Panel B). The ICA was stopped, and the patient underwent cardiac computed tomography angiogram (CCTA) to gain a better anatomical assessment of this anomaly. The CCTA demonstrated right dominance and an anomalous origin of the RCA coming from the left coronary cusp with a slit-like orifice, course between the aortic root and pulmonary outflow tract at the level of the pulmonic valve (Figure 1, Panel D) and 70% proximal RCA stenosis.
Cardiothoracic (CT) surgery was then consulted due to the findings from the CCTA. CT surgery stated that he would be a candidate for a 1-vessel coronary artery bypass grafting (CABG) surgery due to clinically significant CAD within his anomalous RCA.
CT surgery performed an RCA to right internal mammary artery (RIMA) CABG with no intra-operative and early post-operative complications. However, he presented to the emergency department 3 months post-CABG with diaphoresis and lightheadedness following sexual intercourse. Work up was consistent with NSTEMI and repeat CCTA showed that the RIMA to RCA bypass graft was occluded (Figure 1, Panel E).  Echocardiogram was repeated with no significant change from prior and the patient remained asymptomatic during hospitalization so repeat attempt at intervention was deferred pending clinical course.

**Results**
Anomalous RCA arising from the left coronary cusp is a rare congenital cardiac condition and remains a challenge to diagnose and manage.3 Our patient highlights the excellent diagnostic capabilities of CCTA and the benefit of non-invasive imaging in diagnosis for patients with difficult to engage coronary ostium. The CCTA also was able to identify high-risk anatomic features in this patient which enabled for risk stratification and facilitated interventional planning. Regarding treatment, the exact pathophysiology of intermittent myocardial ischemia in anomalous RCA patients remains unknown. For our patient, it is possible that the course of the anomalous RCA between the aorta and pulmonary artery resulted in an acute angle take-off and increased the probability of the development of a slit-like orifice in the RCA, as demonstrated on the CCTA.4 Additionally, as in non-anomalous RCA patients, clinically significant CAD can be a main driver of myocardial ischemia, as seen in this patient. When assessing which anomalous RCA patients to treat, there are three important considerations: high-risk anatomical features, concomitant CAD, and functional imaging.4 This patient clearly required treatment because he had multiple high-risk anatomical variants, and he presented with clinically significant stenosis in his anomalous RCA that required intervention. There is no standard of care for managing anomalous RCA patients.4 Given the difficulty in engaging the RCA, a surgical approach was selected to manage this patient. CABG was chosen over coronary un-roofing/neo-ostium creation because of the lack of manipulation at the aorta/aortic valve which reduces procedural risks.4 Additionally, several studies have proposed that CABG be limited to only patients with significant concomitant CAD within the anomalous vessel, as in this patient.

**Conclusion**
Anomalous RCA arising from the left coronary cusp poses a diagnostic and therapeutic challenge. CCTA can assist with both the diagnosis of anomalous RCA as well as help to identify high risk anatomical features that influence procedural intervention options. There is no standard of care for managing anomalous RCA patients, but when considering CABG several studies have proposed that CABG be limited to only patients with significant concomitant CAD within the anomalous vessel, as in this patient. However, there is an elevated risk of graft failure, as seen in this patient.



**Introduction/Hypothesis:**
The incidence of anomalous right coronary artery (RCA) arising from the left coronary cusp is 0.92%.^1,2,3^ Patients are typically asymptomatic, however depending on the orifice characteristics and the anatomical course of the anomalous coronary artery it carries an increased risk for sudden cardiac death. Given the rarity of anomalous RCA and the typically asymptomatic course for the patients, procedural management is typically reserved for patients with high-risk anatomical features, concomitant coronary artery disease (CAD), and ischemia on functional imaging.^4^ We present a case of a 76-year-old male who presented with non-ST elevation myocardial infarction (NSTEMI) secondary to clinically significant CAD and was later found to have an anomalous RCA originating from the left coronary cusp with several high-risk anatomical features.

**Methods**
A 76-year-old male with a past history of systemic hypertension, chronic kidney disease and ischemic stroke who presented with cardiac chest pain. The patient’s chest pain occurred at rest, and he also endorsed associated diaphoresis and palpitations. In the emergency department, his troponins had dynamic rise, rising from 11 ng/L to 136 ng/L. His electrocardiogram on admission did not demonstrate signs of ischemia, however the following day exhibited T-wave inversions in the inferior leads. A transthoracic echocardiogram revealed no regional wall abnormalities with a left ventricular ejection fraction of 63%. He then underwent invasive coronary angiography (ICA), which demonstrated a normal anatomic origin of the left coronary arterial system from the left coronary cusp (Figure 1, Panel A), however, the right coronary ostium could not be identified by non-selective aortogram (Figure 1, Panel B). The ICA was stopped, and the patient underwent cardiac computed tomography angiogram (CCTA) to gain a better anatomical assessment of this anomaly. The CCTA demonstrated right dominance and an anomalous origin of the RCA coming from the left coronary cusp with a slit-like orifice, course between the aortic root and pulmonary outflow tract at the level of the pulmonic valve (Figure 1, Panel D) and 70% proximal RCA stenosis.
Cardiothoracic (CT) surgery was then consulted due to the findings from the CCTA. CT surgery stated that he would be a candidate for a 1-vessel coronary artery bypass grafting (CABG) surgery due to clinically significant CAD within his anomalous RCA.
CT surgery performed an RCA to right internal mammary artery (RIMA) CABG with no intra-operative and early post-operative complications. However, he presented to the emergency department 3 months post-CABG with diaphoresis and lightheadedness following sexual intercourse. Work up was consistent with NSTEMI and repeat CCTA showed that the RIMA to RCA bypass graft was occluded (Figure 1, Panel E).  Echocardiogram was repeated with no significant change from prior and the patient remained asymptomatic during hospitalization so repeat attempt at intervention was deferred pending clinical course.

**Results**
Anomalous RCA arising from the left coronary cusp is a rare congenital cardiac condition and remains a challenge to diagnose and manage.^3^ Our patient highlights the excellent diagnostic capabilities of CCTA and the benefit of non-invasive imaging in diagnosis for patients with difficult to engage coronary ostium. The CCTA also was able to identify high-risk anatomic features in this patient which enabled for risk stratification and facilitated interventional planning. Regarding treatment, the exact pathophysiology of intermittent myocardial ischemia in anomalous RCA patients remains unknown. For our patient, it is possible that the course of the anomalous RCA between the aorta and pulmonary artery resulted in an acute angle take-off and increased the probability of the development of a slit-like orifice in the RCA, as demonstrated on the CCTA.^4^ Additionally, as in non-anomalous RCA patients, clinically significant CAD can be a main driver of myocardial ischemia, as seen in this patient. When assessing which anomalous RCA patients to treat, there are three important considerations: high-risk anatomical features, concomitant CAD, and functional imaging.^4^ This patient clearly required treatment because he had multiple high-risk anatomical variants, and he presented with clinically significant stenosis in his anomalous RCA that required intervention. There is no standard of care for managing anomalous RCA patients.^4^ Given the difficulty in engaging the RCA, a surgical approach was selected to manage this patient. CABG was chosen over coronary un-roofing/neo-ostium creation because of the lack of manipulation at the aorta/aortic valve which reduces procedural risks.^4^ Additionally, several studies have proposed that CABG be limited to only patients with significant concomitant CAD within the anomalous vessel, as in this patient.

**Conclusion**
Anomalous RCA arising from the left coronary cusp poses a diagnostic and therapeutic challenge. CCTA can assist with both the diagnosis of anomalous RCA as well as help to identify high risk anatomical features that influence procedural intervention options. There is no standard of care for managing anomalous RCA patients, but when considering CABG several studies have proposed that CABG be limited to only patients with significant concomitant CAD within the anomalous vessel, as in this patient. However, there is an elevated risk of graft failure, as seen in this patient.



Cardiac Computed Tomography Angiography for Difficult to Engage Anomalous Coronary Arteries: A Case of Right Coronary Artery Arising from Left Coronary Cusp

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.