Advances in imaging techniques and the widespread adoption of screening protocols have led to a significant increase in the diagnosis of anomalous aortic origin of the coronary arteries (AAOCA) in recent years. Patients with AAOCA may present with a wide range of clinical manifestations, making diagnosis challenging and sparking debates regarding treatment, particularly in asymptomatic individuals. While various management approaches exist for this condition, there is no consensus on the optimal treatment strategy. In today’s article, a group of 23 experts in the field created a consensus document after reviewing 158 publications.

One of the primary challenges faced is the lack of consensus on nomenclature used to describe these anomalies. Consequently, there is no standardized approach to identifying, describing, or classifying them. For example, articles using Angelini’s classification may differ significantly from those employing the 11th edition of the International Classification of Diseases. The prevalence of AAOCA in the general population is less than 1%. These anomalies may occur in isolation or in association with syndromes. For instance, they are observed in 6% of patients with tetralogy of Fallot and are twice as common in bicuspid aortic valves compared to tricuspid valves. An association with connective tissue disorders, such as Marfan syndrome, has also been documented. Depending on the source, prevalence rates vary from 0.6% (in autopsy series of sudden cardiac death) to over 5% in noninvasive screening protocols. The most common form is the anomalous origin of the circumflex artery from the right coronary artery or the right sinus of Valsalva. A study of more than 5000 adolescents found that anomalous origin of the right coronary artery from the left sinus of Valsalva (R-AAOCA) was three times more common (0.33%) than anomalous origin of the left coronary artery from the right sinus of Valsalva (0.12%).

The primary concern with these anomalies is not the anomalous origin itself but the potential mechanisms of ischemia they may induce, which can be fixed or dynamic. Fixed stenoses involve ostial narrowing or proximal coronary narrowing, while dynamic stenoses are associated with coronary spasm and/or the intramural or intramyocardial course of the artery. Traditionally, interarterial compression between the aorta and pulmonary artery was believed to be a key mechanism of ischemia. However, recent studies challenge this hypothesis, identifying the intramural segment as the true ischemic mechanism. Under conditions of increased cardiac output, such as stress, dynamic compression of the intramural portion of the coronary artery occurs, reducing the cross-sectional area of the typically oval-shaped vessel. Combined with increased flow resistance due to Hagen-Poiseuille’s law, this leads to distal hypoperfusion and myocardial ischemia. Ostial abnormalities, such as slit-like ostia, hypoplastic ostia, or a coronary takeoff angle of less than 45º (which may act as an intermittent valvular obstruction), also pose high risks for ischemia.

In non-coronary cardiac surgeries, the presence of AAOCA and its variants must be identified. The most common scenario arises in bicuspid aortic valve surgeries, where the circumflex artery may originate from the right sinus of Valsalva and take a posterior course toward the atrioventricular groove, posing a risk of injury during aortotomy. Additional challenges include inadequate myocardial protection and potential coronary compromise by prosthetic sutures. Cases of circumflex artery compression following transcatheter aortic valve implantation have also been described.

To assess the risk associated with a specific AAOCA variant, comprehensive imaging studies are essential. Invasive modalities, such as catheterization with intravascular ultrasound (IVUS), enable functional assessments. However, noninvasive modalities, such as computed tomography (CT), have gained prominence due to their submillimeter spatial resolution, allowing detailed visualization of the origin, course, luminal narrowing, and atherosclerosis. Magnetic resonance imaging (MRI) offers a radiation-free alternative, albeit with limitations such as susceptibility to metallic artifacts and lower spatial resolution. Echocardiography is primarily used in pediatric populations and is not recommended for AAOCA evaluation in adults. For functional analysis, European guidelines explicitly recommend non-pharmacologic imaging tests. Exercise-based or dobutamine stress tests are generally preferred, as they better reflect dynamic coronary flow behavior. While perfusion imaging holds promise, there is no consensus on its protocols, and most studies focus on left ventricular perfusion, with right ventricular perfusion remaining an area for further validation. CT-derived fractional flow reserve is a promising technique, although its application in AAOCA requires further validation. Computational models simulating fluid-structure interactions are emerging as tools to predict coronary flow anomalies and potential solutions.

Both European and American guidelines agree on treating symptomatic patients or those with evidence of ischemia. European guidelines go a step further, recommending surgery in asymptomatic patients with high-risk anatomies (Class IIa recommendation), while American guidelines assign a lower recommendation level (Class IIb). Clinical evaluation of ischemia must consider the AAOCA variant, the patient’s age and activity level (sudden cardiac death risk is higher in individuals under 30), surgical risks, and patient preferences. Anxiety related to sudden cardiac death or the implications of this anomaly in competitive athletes can significantly influence decision-making.

Various surgical techniques are tailored to address the specific mechanisms of ischemia in AAOCA. The most common procedure is “unroofing” for intramural AAOCA, which may include creating a neo-ostium in cases involving the commissure. In centers with experience, surgeons may detach the aortic commissure, perform unroofing, and resuspend the commissure. Ostial stenosis due to hypoplasia or an acute takeoff angle may be corrected with ostioplasty, while reimplantation of the coronary artery into the appropriate sinus is another option. For extrinsic compression caused by the pulmonary artery, lateral translocation or the LeCompte maneuver may be performed. Transseptal AAOCA may require transconal or transinfundibular unroofing. In select cases, surgical revascularization may be employed, although it is not a first-line option due to the dynamic nature of ischemia, which could compromise graft function. Percutaneous treatment is limited by a 13% in-stent restenosis rate at 5 years and should be reserved for non-surgical candidates.

COMMENTARY:

Today’s review article is essential reading for anyone seeking a quick update on the literature surrounding AAOCA. With its iconography and schematic tables, it covers the diagnostic and therapeutic algorithms for these coronary anomalies comprehensively. However, it is worth emphasizing that a significant proportion of AAOCA cases involve multilevel obstructions, and failure to address all levels may result in persistent or recurrent ischemia. Beyond the anatomy of the coronary ostium and the AAOCA course, it is crucial to identify myocardial bridges, which coexist in up to 5% of cases. Failure to treat these segments negates the benefits of other techniques used to repair the proximal segment. For unroofing procedures, it is critical to adequately release the coronary exit from the aorta to effectively address the intramural segment’s ischemic mechanism. Insufficient release renders the length of unroofing futile.

Advances in imaging modalities have revealed the complexity of this pathology. As a result, it is imperative that these patients are treated in referral centers with multidisciplinary teams experienced in imaging, congenital heart disease, and surgical techniques. Customization of surgery is paramount in this condition.

REFERENCE:

Gaudino M, Di Franco A, Arbustini E, Bacha E, Bates ER, Cameron DE, et al. Management of Adults With Anomalous Aortic Origin of the Coronary Arteries: State-of-the-Art Review. J Am Coll Cardiol. 2023 Nov 21;82(21):2034-2053. doi: 10.1016/j.jacc.2023.08.012. Epub 2023 Oct 16. PMID: 37855757.