An anomalous coronary artery from the opposite sinus of Valsalva (ACAOS) represents a congenital disorder with an anomalous location and/or course of the coronary vessel. The prevalence of ACAOS in the general population is around 1 % and they are mostly clinically insignificant and remain often undetected. However, some variants of ACAOS are associated with adverse cardiac events. The possible presence of an interarterial/intramural course is the primary cause for an oval proximal vessel shape and/or proximal vessel narrowing, which may lead under stress conditions to a "dynamic compression" of the vessel (compared to "fixed" stenosis in coronary artery disease). To mimic these conditions, dobutamine and volume challenge is used to invasively measure fractional flow reserve (FFR) during coronary angiography and is seen as the gold standard in assessing the hemodynamic relevance of ACAOS. We established a specialized interdisciplinary clinic for coronary artery anomalies including imaging specialists, invasive cardiologists and congenital heart disease surgeons as correct downstream testing and treatment decision is highly challenging in these patients. Thus, systematic collecting of all available diagnostic methods (invasive and non-invasive) is required to assess the optimal diagnostic procedure and treatment for these patients. Coronary computed tomography angiography (CCTA) is the method of choice to characterize the exact anatomy of ACAOS. However, how functional invasive FFR is associated with anatomical CCTA findings is unknown. Further, diagnostic accuracy of a novel independent research algorithm with computational fluid dynamics (ctFFR) as well as functional imaging (i.e. stress single photon emission computed tomography) in this specific setting is unknown.

The presented project will help to understand the pathophysiology of CAAs with particular focus on ACAOS-IC and improve risk stratification based on non-invasive imaging.

Anomalous coronary arteries (CAA) represent a congenital disorder hallmarked by an anomalous location of the coronary ostium and/or vessel course. Based on the largest study assessing the prevalence and characteristics of CAA detected by coronary computer tomography angiography (CCTA) in Switzerland, the overall prevalence of CAA is 2.6%. However, depending of the type of CAA and its course in relation to the big vessels (aorta and pulmonary artery), not every CAA is accompanied by an increased cardiovascular risk.

Of particular interests are anomalous coronary arteries from the opposite sinus of Valsalva with an interarterial course (ACAOS-IC). Those CAAs represents a congenital disorder with an anomalous location of the coronary ostium and a course of the anomalous vessel between the aorta and the pulmonary artery. The prevalence of ACAOS-IC in the general population is around 1 % and even they are mostly clinically insignificant and remain often undetected.

However, some variants of ACAOS-IC are associated with adverse cardiac events (e.g. sudden cardiac death in young athletes). The possible presence of an intramural course, a course within the aortic wall is the primary cause for an oval proximal vessel shape and proximal vessel narrowing and is suggested to be the primary cause for ischemia. These features may lead under stress conditions to a "dynamic compression" of the vessel (compared to "fixed" stenosis in coronary artery disease). Therefore, to mimic these conditions, dobutamine and volume challenge is used to invasively measure fractional flow reserve (FFRDobutamine) during coronary angiography and is seen as the gold standard in assessing the hemodynamic relevance of ACAOS-IC. Presence of an abnormal FFRDobutamine is one of the most important factors in the decision-making towards surgical repair in ACAOS-IC.

With the frequent use of invasive and non-invasive imaging to rule out coronary artery disease, an increase in absolute numbers of ACAOS-IC is seen and physicians are more confronted with the dilemma of how to manage these patients. Usually the question is whether the ACAOS-IC is a coincidental finding or if the anomaly is causative for the patients' symptoms. Thus, systematic acquisition of all available diagnostic methods (invasive and non-invasive) is required to assess the optimal diagnostic procedure for this patients.

The presented project will help to understand the pathophysiology of CAAs with particular focus on ACAOS-IC and improve risk stratification based on non-invasive imaging.

Inclusion Criteria:

• Age ≥18 years.
• CAA with a clinically indicated testing (noninvasive and/or invasive measurement) at our institution
• Informed consent

Exclusion Criteria:

- None

Patients eligible for study participation have a CAA and a prior, clinically indicated testing (noninvasive and/or invasive measurement) at our institution to evaluate the hemodynamic significance of this coronary anomaly.