Coronary artery anomalies comprise several different congenital malformations and can be found in 0.3 to 5.6% of the population. They can be classified as benign and malignant depending on the vessel course and the potential risk of major cardiovascular events [3].
Trans-septal course of LAD is a malignant coronary anatomy variation since it is a potential cause of sudden cardiac death (SCD) in young athletes. Strenuous physical exercise in patients showing this anomaly has been, in fact, associated with SCD. Among the most important factors responsible for cardiovascular events, there is the dynamic compression of the artery during the cardiac cycle, leading to reduced blood flow during systole [4].
The clinical spectrum of L-ACAOS with a trans-septal course is wide and can mimic other acute heart conditions. Symptoms associated with this condition could be chest pain, syncope, dyspnea, and, as told before, SCD typically after physical exertion [4, 5].
The best non-invasive imaging technique to evaluate the anatomic features of L-ACAOS is ECG-gated CT angiography. This technique can show the most life-threatening features of the anomaly and has a high spatial resolution.
Including this case, there are 6 cases of the right single coronary artery with a subsequent trans-septal course of the left main coronary artery reported in the literature [6].
In the presented case, ICA was not able to show coronary artery anatomy, because the intraseptal tract of the LAD was probably associated to flow anomalies leading to reduced opacification after injection of contrast material in the right sinus of Valsalva. Thus, CCT played a major role in the assessment of coronary artery anatomy. The use of a 256-slice scanner with a very low rotation and acquisition time was of paramount importance for obtaining diagnostic images. In fact, AF often limits the diagnostic accuracy of CCT with conventional CT scanners.
Furthermore, to evaluate myocardial ischemia due to L-ACAOS, the best option is stress-ECG, to mimic physical exercise. Alternatively, an inotropic and chronotropic agent (e.g., dobutamine) with other non-invasive imaging techniques such as cardiac magnetic resonance (CMR) or echocardiography could be useful to simulate physical exertion [4].
Among invasive imaging techniques, intra-vascular ultrasounds (US) are the most useful for the evaluation of anatomical and physiological features of L-ACAOS is ICA, which is effective also in post-surgery follow-up [5].
The most effective and established therapy for this anomaly is surgery, with the un-roofing of the intramural segment and the creation of a neo-ostium, aiming to eliminate dynamic systolic compression, thus reducing the risk of myocardial ischemia and therefore SCD [4, 5].
