EDITORIAL COMMENT
What is the most effective method of detecting anomalous coronary origin in symptomatic patients?*
Aarti Hejmadi, MD* and
David J. Sahn, MD, FACC*,*
* Clinical Care Center for Congenital Heart Disease, Oregon Health & Science University, Portland, Oregon, USA
* Reprint requests and correspondence: Dr. David J. Sahn, L608, Pediatric Cardiology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239-3098, USA.
sahnd{at}ohsu.edu
Whether a coronary artery (CA) anomaly is diagnosed as an isolated anatomical condition or as a condition associated with other forms of congenital heart disease, a timely diagnosis is crucial. Detailed assessment of CA anatomy is an established part of the evaluation of structural heart defects, but it is being increasingly incorporated into the evaluation of chest pain and pre-athletic screens. Catastrophic presentations, especially in apparently asymptomatic athletes, highlight the urgency of a timely diagnosis, a higher index of suspicion, and a more active seeking of detailed symptomatic history. Coronary artery anomalies occur in 0.3% to 0.9% of the population without structural heart defects and in 3% to 36% with structural heart defects (1,2). The proximal course of an anomalously arising CA is a decisive factor in risk stratification and surgical approach (3). A slit-like orifice, a long intramural course, and an acutely angled take-off of a CA are described as high-risk factors (4). An interarterial location between the aorta and pulmonary trunk, coursing either within the aortic wall or outside it, carries a higher risk of sudden death (5–7). Intraluminal narrowing in response to increased wall stress in an intramural location, compressive forces in between the major arterial trunks, or kinking of a tortuous proximal CA are all proposed as reasons for sudden death, typically during or after strenuous exercise. Potentiating high-risk factors is the presence of ostial stenosis or an acutely angled take-off from the sinus.
The article by Frommelt et al. (8) in this issue of the Journal identifies and addresses a unique anatomic substrate and an "at-risk" population. They describe the findings and surgical repair in 10 patients with anomalous origin and interarterial course of the proximal coronaries, presenting over a five-year period. The mean age at diagnosis was 10 years; the mean age in those with an ischemic presentation was 16 years; and the mean age at repair was 13 years. Although the problem has been well elucidated in the adolescent or older population, this article is a first as a problem statement relevant to the pediatric age group. Whereas some of the older children (4 of 10 patients) had an ischemic presentation and all of these had a left CA anomaly, there were a number of important cases that were diagnosed incidentally while ruling out a congenital heart disease (2 of 10 patients), or who presented with chest pain (2 of 10 patients). It would be interesting to know more details about the presentations and evaluation of the last group, because chest pain is a frequent pediatric complaint in outpatient and emergency room settings. What might be the predictors of a sinister cardiac diagnosis in this group? A compilation of the experiences of various centers addressing diagnostic algorithms to manage this subset would be useful to rationalize the detail and expediency of their cardiac evaluation. Anomalous origin of coronary arteries has been known to present as ventricular tachycardia in adults and young patients (9,10). For this reason, and to detect any signs of ischemia, information on electrocardiographic findings of the patients would have been useful.
Transthoracic echocardiography (TTE) has certainly reached a point of spatial resolution to be able to delineate proximal CAs in most pediatric patients, especially infants, who are studied with high-frequency probes along with color Doppler imaging of the CAs. The additional confirmatory role of color Doppler and a detailed evaluation of the relationship of the proximal CAs to the pulmonary artery origin and the aorta at the sinus level makes TTE a robust diagnostic imaging modality.
In this case series, it would seem that there were at least three patients who went in for surgery without catheterization, but we are not informed as to whether they had other non-invasive tests such as magnetic resonance imaging or computed tomography (CT) angiography. Of note, ostial stenosis, confirmed intraoperatively (five of eight patients) was not diagnosed on echo or suspected on preoperative catheterization in any of these cases. One case was diagnosed on cardiac catheterization at another hospital after a syncopal episode, and it is not clear whether that patient had an echo.
In evaluating the images published with this article, the proximal CAs on the two-dimensional echo images shown appear to have lumens 2 to 3 mm at most, seemingly smaller than their actual size—probably because of planar and azimuthal resolution problems related to ultrasound. As previously stated, ostial stenosis was not diagnosed on echo in this series, and no CA abnormalities with coronaries arising or coursing from the posteriorly placed aortic sinuses or portions of the aortic wall were diagnosed in this series.
The diagnostic aspects of this report should be put in perspective of the capabilities of the other non-invasive imaging modalities, especially magnetic resonance coronary angiography (MRCA). Magnetic resonance coronary angiography has proven to have good sensitivity (71% to 100%) and specificity (78% to 100%) for the detection of coronary arterial stenosis (11). With recent technical advancements and modifications such as respiratory navigators, MRCA accurately imaged CA disease in the proximal and middle segments (12). X-ray coronary angiography (XRA) is traditionally considered the gold standard for CA evaluation, but of course it is invasive, involves ionizing radiation, is more resource consuming, and puts the patient through more discomfort, while carrying all the risks of a catheterization procedure. Importantly, X-ray angiography is not able to correctly identify the interarterial course of an anomalous CA (11,12). X-ray angiography may be unable to differentiate between the high-risk interarterial anatomy versus the lower risk septal, retro-aortic, or anterior free wall aorta courses (3). In numerous studies comparing the reliability and diagnostic accuracy of MRCA with XRA, MRCA unambiguously visualized the proximal CAs, even in those cases in which XRA was equivocal (3,13,14). As a tomographic technique, and with recent three-dimensional advancements, MRCA can precisely characterize the region of the aortic sinuses and proximal CAs (Fig. 1), in contrast with XRA, which as a projection technique is limited to some views that profile the CAs as separate from the aortic sinuses and walls and is much more operator-dependent for that reason. In one series, XRA and MRCA had 100% agreement in the differentiation between normal and abnormal anatomy and in the arterial origin, but there was up to a 16% difference in opinion regarding the proximal course (3). Although MRCA previously required long breath-holding by the patient, recent development of respiration navigator methods obviates this necessity, making the procedure more acceptable to patients, especially children. Breath-holds as short as 10 to 15 s can allow three-dimensional angiographic visualization (15).
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Figure 1 Local maximal intensity projection from three-dimensional navigator acquisition in a 16-year-old patient with anomalous origin of the left main coronary artery (LMCA) from the posterior sinus of Valsalva. The coronary arises at an acute angle and appears to have a short intramural segment. RCA = right coronary artery. Figure courtesy of Giles Wesley Vick III, MD, Texas Childrens’ Hospital, Houston, Texas.
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Transesophageal echo has proven to be useful in assessing CA origin and proximal course, but it is semi-invasive and would not be suitable for wider use as a screening technique. Contrast-enhanced fast CT, using intravenous contrast agents, involves substantial radiation exposure, but it is as robust as MRCA for evaluating origin and course, although not as effective in characterizing atheromatous CA wall changes (16). Although accomplishing three-dimensional cardiac imaging with fast multislice CT requires less technical expertise than MRCA, there are not many reports describing the role of CT in diagnosing CA anomalies.
Lastly, the indications and usefulness of exercise testing in asymptomatic adolescents are controversial because a negative test does not help determine management to any extent and a negative finding often occurs even in patients with high-risk anatomical substrates.
Frommelt et al. (8) describe the surgical technique adopted in their case series following the unroofing technique initially reported by Mustafa et al. (17), and ostial-enhancing techniques described by Nelson-Piercy et al. (18) and Van Son and Haas (19). Though symptomatic presentations are an accepted indication for surgical repair, repair and the timing of repair in asymptomatic individuals are less clear. The diagnosis of anomalous proximal CA, especially high-risk types as described above might be in itself an indication for surgery. Granted that the first symptomatic presentation may be the last, that none of the imaging modalities have a predictive value for the occurrence of an adverse cardiac event, that the cumulative risks cannot but increase, that corrective surgery bears good results, and that this is a medicolegally contentious issue, it would seem unreasonable to wait for any prolonged period after a diagnosis has been made, even in the asymptomatic group. The appearance of aortic incompetence after resuspension of the aortic cusps post repair was noted to be mild in 75% of the operated cases, with a median follow-up interval of 1.5 years. Continued follow-up would be important to determine the progression of aortic incompetence and the additive influence of systemic hypertension and aortic annular dilation with aging. Although the neo-ostium was found to be widely patent on follow-up, the incidence and risks of restenosis also require long-term observation. Interestingly, the study used TTE and coronary angiography to evaluate for restenosis, although the latter modality had failed to diagnose ostial stenosis preoperatively.
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Conclusions
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The authors’ report raises our awareness that screening echoes need to be carefully performed, especially when history and symptoms suggest risk. The crucial issue is that the sensitivity, specificity, and accuracy of TTE in elucidating the diagnostic features of these abnormalities remain unknown, and they are not addressed in the small but important series reported herein. Granted that CA anomalies are rare diagnoses, a prospective multicenter blinded- read study of the ostium, origin, and course of CAs, including as large a number of cases with surgical verification of findings as is possible is warranted. At the same time, comparing findings on TTE and MRCA would be useful.
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Footnotes
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* Editorials published in the Journal of the American College of Cardiology reflect the views of the authors and do not necessarily represent the views of JACC or the American College of Cardiology. 
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References
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