Anomalous Right Coronary Artery From Left Coronary Cusp With Inter-Arterial Course: Evaluation and Management

Disclosure: The authors report no conflicts of interest regarding the content herein.

The authors can be contacted via Dr. Jon George at georgej@deborah.org.

Abstract

Anomalous origin of the right or left coronary artery from the contralateral sinus of Valsalva is rare. Many of these coronary anomalies can be benign and are detected as incidental findings on diagnostic coronary angiography. However, some coronary anomalies can be potential causes of myocardial ischemia, syncope, and sudden cardiac arrest, particularly in patients with an inter-arterial course of the anomalous vessel. Here, we present a case of a patient with anomalous right coronary artery with an inter-arterial course and review the clinical relevance and management of coronary anomalies with corroborating images. 

Case

A 58-year-old male with a past medical history of hypertension presented with a chief complaint of intermittent sub-sternal chest pain. He described the pain as non-radiating and pressure-like in nature. Over the prior few months, he noticed intermittent central chest discomfort during emotional or stressful situations. He denied shortness of breath, palpitations, lightheadedness, or syncope. He denied family history of coronary artery disease or premature sudden cardiac death. Laboratory analysis on admission was unremarkable, with negative cardiac biomarkers including troponin. Electrocardiogram (ECG) showed normal sinus rhythm with incomplete left bundle branch block. Computed tomography (CT) coronary angiography revealed right coronary dominance, but there was a malignant course of the right coronary artery (RCA) originating from the left coronary cusp, coursing anterior to the aorta and posterior to the right ventricular outflow tract (RVOT). The segment coursing between the aorta and the RVOT was narrowed compared to the remainder of the RCA (Figure 1). There was no significant disease in the left main, left anterior descending (LAD), or left circumflex (LCX) arteries. The patient underwent cardiac catheterization with coronary angiography. Aortic root injection confirmed origin of the RCA from left coronary cusp (Figure 2). Selective coronary angiography revealed normal left coronaries and an RCA originating from the left coronary cusp (Figure 3), appearing to take an inter-arterial course between the pulmonary artery and the aorta with possible compression of the proximal segment. 

The cardiothoracic surgery team was consulted for surgical repair of the anomalous RCA given the patient’s symptoms, malignant course of the vessel, and evidence of external compression of the proximal portion of the RCA. The patient underwent surgical correction of the anomalous origin of RCA, which was found to exit between the RVOT and the aortic root (Figure 4). The proximal RCA was transected and ligated, and then re-implanted to the ascending aorta (Figure 5). Transesophageal echocardiography post surgical procedure revealed normal left ventricular ejection fraction of 55-60%, and no valvular abnormalities. The patient tolerated the procedure well, and was subsequently discharged home on post-operative day 5. He was seen in follow up 2 weeks after discharge, when he was recovering well and reported no recurrence of symptoms. 

Discussion

The incidence of coronary anomalies is estimated at 0.28 to 1.3% of the population.^1-5 Although most coronary anomalies are incidentally detected on diagnostic coronary angiography and are clinically insignificant, some coronary anomalies have been associated with increased risk of sudden cardiac death (SCD). Anomalous origin of coronary artery is second only to hypertrophic cardiomyopathy as the leading cause of SCD in young athletes. The highest risks were found to be associated with anomalous origin of coronary arteries that arise from the contralateral sinus of Valsava. The mechanism of SCD in these patients is thought to be due to myocardial ischemia occurring during physical exertion and resultant arrhythmia.⁵ 

The prevalence of an anomalous origin of the RCA (ARCA) arising from the left coronary cusp with inter-aterial course varies between 0.026 and 0.25%.³ An ARCA is more common than anomalous origin of left coronary artery (ALCA), but ALCAs seem to be responsible for up to 85% of SCDs related to anomalous origins of coronary arteries.⁷ An ARCA from the left coronary cusp with an inter-arterial course between the aorta and pulmonary artery can increase risks of myocardial ischemia, arrhythmia, syncope, and sudden cardiac death. Possible mechanisms of ischemia-induced SCD by the anomalous RCAs from left coronary sinus have been suggested: mechanical compression of the RCA by the pulmonary artery and aorta during physical exertion; acute angulation at the ostium of RCA and left coronary sinus, and abnormal slit-like RCA orifice in the aortic wall that collapses during exercise; anomalous RCA passage through the aortic commissure causing compression by the aortic commissure; vasospasm of the anomalous coronary artery^3,6; and intramural course of the anomalous RCA causing compression due to aortic expansion during exercise.⁶ Studies utilizing intravascular ultrasound (IVUS) on patients with anomalous origins of coronary arteries have shown that the proximal intramural segment is 20-70% smaller in circumference than the distal segment of the same coronary artery because of lateral compression.⁷ In addition, previous autopsy studies have found that a slit-like orifice structure and acute angle takeoff are more common in SCD patients.⁸

Clinical presentation of these patients ranges from asymptomatic to nonspecific chest pain, palpitations, dizziness, or syncope. While SCD is usually associated with young athletes, most other clinical manifestations are frequently seen in older adults. The diagnosis of anomalous coronary arteries can be made by the use of conventional coronary angiography or CT angiography, or cardiac magnetic resonance imaging (MRI). Both cardiac MRI and CT are becoming increasingly popular imaging modalities for detecting coronary anomalies. They allow three-dimensional representation of cardiac anatomy, and permit reliable information of the takeoff portion and course of the anomalous coronary artery.⁷

SCD in asymptomatic patients occurs more frequently in patients with ALCAs, and therefore surgical repair is recommended for these patients.⁷ Sudden death is rare in asymptomatic patients with ARCAs. Treatment of anomalous RCAs is varied and controversial. Previous studies recommended that young patients (<35 years old) with ARCAs and symptoms or ischemia should undergo surgery. Older patients without symptoms or ischemia do not need surgical repair and strenuous exercise should be limited in these patients. An algorithm to guide clinical management for these patients and to standardize the treatment strategy has been proposed⁷: patients with ALCAs are recommended surgical intervention due to their associated high risk of SCD; patients with other coronary anomalies are recommended intervention if they have symptoms suggestive of ischemia, positive nuclear stress test, or high-risk coronary anatomy on CTA (long intramural segment, ostial abnormalities, or dynamic changes of the ostium within the cardiac cycle); dynamic exercise restriction is recommended for patients who are waiting for surgery or refuse surgical intervention.

Many surgical techniques have been used, including coronary reimplantation, unroofing the intramural segment, and coronary artery bypass grafting.^1,5,7,9 Coronary reimplantation requires excision of the proximal RCA at its exit point from the aorta and reimplantation into the appropriate sinus. Reimplantation has the risk of neo-ostial stenosis and may result in the need for coronary artery bypass grafting.⁸ When the anomalous coronary artery courses within the aortic wall, surgical unroofing of the intramural segment can be considered.⁵ This technique involves excision of the roof of the intramural segment and may alleviate coronary compression. Surgical unroofing has good immediate results, but carries the risk of aortic insufficiency even late after surgery.^5,9 Coronary artery bypass grafting eliminates the need to open the aorta, but subjects the patient to graft thrombosis due to competitive flow. Ligation of the proximal coronary is recommended to prevent competitive flow.^5,7,9

Long-term impact of surgical intervention in patients with anomalous coronary artery from the opposite sinus of Valsalva is uncertain. Krasuski et al found similar survival in patients who received medical therapy or surgical intervention in a single-center cohort study over a 40-year period.⁹ Additional studies are needed to determine the long-term impact of surgery on these patients.

Summary

ARCA from the contralateral sinus of Valsalva is often asymptomatic, but can be a potential cause of ischemic symptoms and SCD. Treatment for ARCAs should be made based on the patient’s age, symptoms, detection of ischemia, and the course of the anomalous vessel. In our case, surgical correction was performed due to patient’s chest pain symptoms, malignant course of the ARCA, and evidence of external compression of the coronary artery. 

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