High takeoff of the right coronary artery from the ascending aorta by echocardiography is widely considered a normal variant. When very high, it may be considered abnormal but relatively benign. Reference Yamanaka and Hobbs1 Currently, limited data are available regarding this diagnosis and its implications. Several case reports have documented a high takeoff of the right coronary noted during preoperative evaluation or at the time of cardiac surgery for an unrelated cardiac problem. Reference Tarhan, Kehlibar and Yilmaz2,Reference Ogino, Miki, Ueda, Tahata and Morioka3,Reference Nishi, Mitsuno, Tanaka, Ryomoto, Fukui and Miyamoto4,Reference Alpaslan and Onrat5 In a recent review of the anatomy of high takeoff of the coronary artery, the prevalence was noted to be approximately 0.2%, with 84% of these being right coronary arteries. Reference Loukas, Andall and Khan6 The incidence of sudden death in these patients ranges from 0.006 to 0.02%, depending on the criteria that are used for defining high takeoff. Reference Tarhan, Kehlibar and Yilmaz2
At our institution, it was noted that several patients who were initially thought to have a high takeoff of the right coronary artery by echocardiogram were later found to have an anomalous right coronary artery from the left coronary sinus by computerized tomographic angiography, and some of these patients also had high-risk features such as intramural course. It is important to correctly diagnose these lesions early and risk stratify these patients, due to the known risk of sudden death in patients with an anomalous right coronary artery. This objective is particularly important in patients with a malignant or intramural course. Current guidelines suggest that surgical intervention is recommended in patients with anomalous right or left coronary artery with ischaemia or inducible ischaemia on exercise testing and is reasonable in those who are asymptomatic but have higher-risk features such as an intramural course of the left main coronary artery. Reference Warnes, Williams and Bashore7 Evidence is less clear in patients who are asymptomatic with an anomalous right coronary artery. Currently, these patients are not typically referred for surgery unless there is evidence of coronary compression, obstruction to flow through the coronary, or hypoplasia of the vascular wall. Reference Warnes, Williams and Bashore7,Reference Brothers, Frommelt, Jaquiss, Myerburg, Fraser and Tweddell8 Despite these recommendations, the ability to accurately identify all patients at risk for sudden cardiac death is imperfect. The ability to appropriately risk stratify patients is particularly difficult if the initial diagnosis is incorrect.
Given that some patients with an anomalous right coronary artery with high-risk features were initially thought to have a high takeoff of the right coronary artery, the risk of misdiagnosis, and the ongoing controversies regarding the management of patients with an anomalous right coronary artery, we felt that it was important to further investigate patients with high takeoff of the right coronary artery suspected by echocardiography. Accurate diagnosis is of utmost importance when determining risk and planning treatment strategy. We hypothesized that given the limitations of echocardiography, a high takeoff of the right coronary artery suspected by echocardiography could indicate the presence of a higher-risk coronary anomaly and may require further investigation. Therefore, the aim of this study was to test the hypothesis that given the limitations of echocardiography, a high takeoff of the right coronary artery suspected by echocardiography may be associated with the presence of an anomalous aortic origin of the right coronary artery with an intramural course requiring further investigation.
Methods
A retrospective chart review was conducted to include patients evaluated at the University of Florida Congenital Heart Center from January 2010 through September 2015 with International Classification of Disease (ICD) codes associated with coronary arterial abnormalities. Patients with ICD diagnoses associated with any other congenital heart disease were excluded from the analysis in order to identify only those patients with isolated coronary arterial abnormalities. Additionally, patients with coronary dilation but normal coronary origins were excluded from the analysis. The initial diagnosis was identified on the initial echocardiography report, and the confirmatory diagnosis was identified on the final computerized tomographic angiography report.
The University of Florida Congenital Heart Center imaging approach for evaluating the origins of the coronary arteries includes examination of the coronary ostium in the parasternal short-axis view by both 2-dimensional and colour Doppler echocardiography (Fig. 1), with further evaluation of the coronary artery origin in the parasternal long-axis view, if necessary. By echocardiography, coronaries originating above the sinotubular junction are considered high takeoff.
Computerized tomographic angiography at the University of Florida is performed using a 320-slice Aquilion ONE scanner (Toshiba Medical Systems Corp., Tustin, CA). Computerized tomographic angiography is done using intravenous contrast with 2 ml/kg of low-osmolar iodine contrast medium (Visipaque 320) injected manually via 24-gauge or larger peripheral catheter or single-lumen peripherally inserted central catheter line at the rate of 0.5ml/s. Scanning is initiated after the contrast bolus is administered, and scan volume typically extends from the thoracic inlet to just below the diaphragm. Scans are performed in a cranial-caudal direction with parameters adapted to the patient’s weight. Postprocessing of the multidetector CT scans are performed on the picture archiving and communication system (PACS). Origin from the right or left coronary sinus is determined based on position relative to the right and left coronary sinus (Fig. 2). A high origin of the right coronary artery is diagnosed if the right coronary artery origin arises above the sinotubular junction (Fig. 3). Orifice dimensions in 2 axes are measured, and the intramural course is then identified if present based on previously published criteria with emphasis on the acute angle of origin from the aorta, slit-like orifice, and elliptical cross-sectional shape. Reference Miller, Anavekar, El Yaman, Burkhart, Miller and Julsrud9
This retrospective chart review study was approved by the University of Florida Institutional Review Board.
Results
There were 934 patients initially identified as having an ICD code associated with a coronary anomaly. Of those identified, 756 patients were excluded due to an ICD code associated with other congenital heart disease, and 116 patients were excluded due to a diagnosis involving the coronary artery but not related to coronary origin. The final study group consisted of 62 patients noted to have coronary arteries with an abnormal origin via ICD coding (Fig. 4).
On review of the initial echocardiograms of these 62 patients identified, 24 patients had a high takeoff of the right coronary artery, 23 had anomalous right coronary artery, 12 had anomalous left coronary artery, and 3 were either not well seen or noted to be normal on the initial echocardiogram (Fig. 4).
As demonstrated in Fig. 4, on further review of the 24 patients with high takeoff of the right coronary artery on their initial echocardiogram, computerized tomographic angiography was performed in 20 patients and documented the following findings:
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three patients had anomalous right coronary artery from the left coronary sinus,
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six patients had high takeoff of the right coronary artery that originated above the left sinus,
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six patients had high takeoff of the right coronary artery that originated above the correct right sinus, and
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five had normal origins of their coronary arteries by computerized tomographic angiography.
There were 4 patients of the 24 who had high takeoff of the right coronary artery on their initial echocardiogram and had not yet undergone computerized tomographic angiography at the time this review was conducted. Therefore, out of 20 patients with initial echocardiogram diagnosis of high takeoff of the coronary artery and confirmatory computerized tomographic angiography, 12 patients were correctly identified as having high takeoff, making the positive predictive value of echocardiography only 60%.
Further analysis of patients with confirmed high takeoff by computer tomographic angiographic studies revealed that of the 9 patients with high takeoff from the left, 6 (67%) had an intramural course, and 3 (33%) did not have an intramural course. Additionally, when looking at the 6 patients with high takeoff above the right coronary sinus, none of them had an intramural course (Fig. 5).
Discussion
The reported incidence of the anomalous aortic origin of the coronary artery ranges from < 0.1 to 1%, Reference Brothers, Frommelt, Jaquiss, Myerburg, Fraser and Tweddell8,Reference Tuo, Marasini, Brunelli, Zannini and Balbi10–Reference Davis, Cecchin, Jones and Portman12 with anomalous aortic origin of the right coronary artery typically being anywhere from 3 to 6 times more prevalent than the anomalous aortic origin of the left coronary artery. Reference Brothers, Frommelt, Jaquiss, Myerburg, Fraser and Tweddell8 Currently, the anomalous aortic origin of the coronary artery collectively represents the second-leading cause of sudden cardiac death in young athletes. Approximately 13–17% of sudden cardiac death cases in this population can be linked to a congenital coronary anomaly. Reference Maron, Doerer, Haas, Tierney and Mueller13,Reference Maron, Shirani, Poliac, Mathenge, Roberts and Mueller14 The highest risk of sudden cardiac death is associated with anomalous aortic origin of the left coronary artery, despite increased prevalence of anomalous aortic origin of the right coronary artery. Reference Taylor, Rogan and Virmani15 The increased risk in patients with anomalous aortic origin of the coronary artery, particularly in patients with high-risk features, is thought to be due to decreased coronary flow which may lead to myocardial ischaemia or ventricular arrhythmia. Reference Brothers, Frommelt, Jaquiss, Myerburg, Fraser and Tweddell8
While anomalous aortic origin of the left coronary artery from the right coronary sinus represents a higher-risk population with regard to sudden cardiac death in young athletes, anomalous aortic origin of the right coronary artery from the left coronary sinus has also been reported to have increased risk of ischaemia and sudden cardiac death when compared to the general population. Reference Taylor, Rogan and Virmani15 This risk of sudden death in patients with anomalous aortic origin of the right coronary artery from the left coronary sinus is of increased concern when certain high-risk features are present. Reference Tarhan, Kehlibar and Yilmaz2 Higher-risk features of this lesion include an interarterial course with an intramural segment, a slit-like orifice, and an acute angle of origin. Reference Loukas, Andall and Khan6
With current advances in technology and increased use of echocardiography, congenital coronary arterial abnormalities will likely be suspected or identified more frequently. Additionally, the use of echocardiography as a screening tool for young athletes has gained favour in recent years. While identification of an anomalous aortic origin of the coronary origin is possible by echocardiography, it can be difficult, particularly when the coronary origin is higher than typical. Consequently, it is recommended to obtain additional imaging if the coronary origin cannot be identified by echocardiogram. Reference Brothers, Frommelt, Jaquiss, Myerburg, Fraser and Tweddell8,Reference Cheezum, Liberthson and Shah16 In an attempt to appropriately risk stratify and appropriately manage asymptomatic patients with anomalous aortic origin of the coronary artery, further workup with stress test with nuclear perfusion scan or stress echocardiography is often utilized to evaluate for ischaemia; however, this strategy does not identify all at risk patients. Reference Warnes, Williams and Bashore7,Reference Brothers, Frommelt, Jaquiss, Myerburg, Fraser and Tweddell8
Current guidelines are more clear for the anomalous aortic origin of the left coronary origin or when there is documented myocardial ischaemia. Currently, recommendations include evaluation of coronary origin in patients who have experienced any of the following Reference Warnes, Williams and Bashore7 :
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aborted sudden death,
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life-threatening arrhythmia that is unexplained,
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symptoms of ischaemia, and
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ventricular dysfunction.
Guidelines also suggest that computerized tomographic angiography is useful as an initial screening tool to assess coronary origin. Surgery is typically recommended for patients with any of the following Reference Warnes, Williams and Bashore7 :
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anomalous aortic origin of the left main coronary artery with interarterial course,
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anomalous aortic origin of the left main coronary artery with intramural course,
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anomalous aortic origin of either coronary artery associated with documented coronary ischaemia due to coronary compression or intramural course, and
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anomalous aortic origin of the right coronary artery with interarterial course and documented ischaemia.
Uncertainty exists regarding the appropriate management of asymptomatic patients with anomalous aortic origin of the right coronary artery from the left coronary sinus, given the low but alarming risk of sudden cardiac death. Reference Taylor, Rogan and Virmani15 Current treatment strategies for asymptomatic patients with anomalous aortic origin of the right coronary from the left coronary sinus and no evidence of ischaemia can vary. Strategies may include the following Reference Brothers, Frommelt, Jaquiss, Myerburg, Fraser and Tweddell8,Reference Cheezum, Liberthson and Shah16 :
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permission to exercise after appropriate counselling of risk with observation for symptoms of ischaemia,
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restriction from exercise (which is less commonly recommended), or
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surgical intervention if high-risk features are present on imaging.
Currently, guidelines suggest that surgery may be considered without evidence of myocardial ischaemia if there is coronary compression, hypoplasia of the vessel wall, or obstruction to coronary flow. Reference Warnes, Williams and Bashore7 Despite the current recommendations, limitations still exist in identifying all patients at risk for sudden cardiac death.
Despite the current uncertainties, significantly more data exists about patients with anomalous aortic origin of the right coronary origin from the left coronary sinus than about patients with high takeoff of the coronary artery, particularly regarding the associated risk. Available information would suggest that isolated high takeoff of the coronary artery above the appropriate sinus is a benign lesion. Thus, identification of high takeoff of the coronary artery above the appropriate sinus by echocardiography would typically not require any further evaluation. In reality, however, although identification of high takeoff of a coronary artery by echocardiography is feasible, the ability to visualize the exact coronary origin in relation to each coronary sinus by echocardiography and to assess for high-risk features by echocardiography remains somewhat limited.
Value of this analysis
Based on our findings, we propose that the specific site of origin of the right coronary with a high takeoff is more predictive of a potentially high-risk course than simply noting high takeoff alone. Patients who had high takeoff of the right coronary artery above the left coronary cusp were more likely to have high-risk features than those who had high takeoff of the right coronary from above the normal right coronary cusp. Simply identifying high takeoff alone is insufficient when assessing risk. Based on these findings, we make the following recommendations:
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It is a fact that simply identifying the presence of high takeoff of the right coronary artery has important value, especially if the patient will undergo cardiac surgery for any reason because the surgeon will benefit from the knowledge of this high takeoff when cannulating the aorta for placement of a cardioplegia catheter and when incising the aorta.
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Based on our analysis, we now recommend that any patient with high takeoff of the right coronary artery should undergo additional imaging with computerized tomographic angiography to identify the precise location of the origin of the coronary artery.
Limitations
Our analysis has several limitations:
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We acknowledge that this pathology is rare, and therefore, our cohort is small; therefore, the generalizability of our analysis may be limited. Overall, numbers were limited in this study, and therefore, moving forward, it will be important to evaluate the data from a larger, prospective study in order to better guide the diagnosis and management of patients with high takeoff of the coronary artery.
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This analysis is a retrospective review and has all of the limitations associated with retrospective analyses.
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Due to the nature of the study, we acknowledge that initial echocardiographic diagnosis may vary based on image quality as well as discrepancies amongst interpreting physicians.
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Echocardiography has significant limitations in its ability to accurately determine the exact origin of a coronary artery when the takeoff is high. However, accurate diagnosis is necessary in order to appropriately risk stratify patients. Thus, it is reasonable to further image patients identified as having high takeoff of the coronary artery by echocardiogram using the more sensitive computerized tomographic coronary angiography. This strategy facilitates more accurate identification of the location of the origin of the coronary artery and potentially delineates high-risk features. Additionally, based on the diagnosis as confirmed by computerized tomographic angiography, further provocative testing may be done in order to assess risk and guide management.
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Finally, the findings of this study are based on the actual analytic cohort, which is a real-world cohort obtained using the following methodology: A large population of people with or without anomalous right coronary artery never get an echocardiogram or see a cardiologist. Of those people who actually see a cardiologist for appropriate reasons, some get an echocardiogram, and some do not. Some of those people who get echocardiograms have findings that suggest a high takeoff of the right coronary artery. Then the reader of the echocardiogram decides if there is what looks like a high takeoff of the right coronary artery or the suggestion of a high takeoff of the right coronary artery reports it. This decision can be fairly subjective. And then, it is up to the primary cardiologist, who by some method that is not often consistent amongst cardiologists decides if they will pursue further testing (such as computerized tomographic angiography) in a given patient. This subset of patients forms the analytic cohort of this study. Thus, this analysis only captures those paediatric-age patients who happen to get referred to a cardiologist where an echocardiogram is done for appropriate reasons and whose echo reader decides rather subjectively that there is what looks like high takeoff of the right coronary artery or suggestion of one. Image quality from patient to patient and machine to machine varies, which impacts the accuracy of the diagnosis and thus influences who eventually is evaluated with computerized tomographic angiography. Therefore, the inclusion and exclusion of patients in this analytic cohort can vary over time secondary to a number of complex variables. Nevertheless, these variables do not impact the recommendations reported in our manuscript; these recommendations remain valid despite these variations.
Conclusion
Echocardiography can accurately identify high takeoff of the right coronary artery; however, echocardiography has limited ability to accurately determine the exact origin of a coronary with a high takeoff. Therefore, based on our findings, patients with high takeoff of the right coronary artery identified by echocardiography should undergo additional imaging with the more sensitive computerized tomographic coronary angiography once high takeoff of the coronary artery is identified by echocardiogram. This strategy facilitates more accurate identification of the location of the origin of the coronary artery and allows more precise risk stratification. Further studies are needed with a larger cohort of patients in order to assess the effectiveness of echocardiography versus computerized tomographic angiography in accurately diagnosing and assessing risk for patients with high takeoff of the coronary artery. Additionally, studies to evaluate long-term outcomes in patients with high takeoff of the coronary artery will assist in guiding the management of this patient population.
Acknowledgements
None.
Financial support
None.
Competing interests
None.
Ethical standard
The authors assert that all procedures contributing to this work comply with the ethical standards of the relevant national guidelines on human experimentation and with the Helsinki Declaration of 1975, as revised in 2008.