Sudden death in a young female with an under-recognised coronary anomaly

Anomalies of the coronary arteries represent some of the most opinion-dividing topics in cardiopathology, particularly due to their relationship with sudden cardiac death, which frequently remains unclear.

An anomaly of the coronary arterial anatomy can be defined as any coronary pattern with a feature rarely encountered in the general population[1]. Normally, the left anterior descending artery (LAD) lays in the anterior interventricular groove and provides the anterior septal perforator branches[2], while either the right coronary artery (RCA) or the circumflex artery (LCx) provides the posterior septal perforator branches through the posterior descending branch[3]. Thus, the LAD is responsible for most of the blood flow to the interventricular septum, the RCA for the atrioventricular node and the posterior descending artery for the posterior portion of the interventricular septum[4]. The first septal artery typically arises from the proximal segment of the LAD (Figure 1) and is considered by angiographers the most important landmark along the course of the LAD to separate the first segment of the LAD from its middle segment[5]. Septal vessels have a horizontal or oblique course extending throughout the epicardium and the myocardium to the endocardium; this course is approximately perpendicular to the cardiac wall and parallel to the anteroposterior (transverse) plane of the interventricular septum. A complex anastomotic system connects the homocoronary and intercoronary collaterals[3, 4].

Septal branches can be classified into two categories according to their structure: straight vessels or branching vessels. Straight vessels cross the whole myocardial wall, while branching vessels have branches at different wall levels[2].

We herein report the case of a young female whose coronary anatomy was characterised by the absence of any septal perforator branch in the proximal segment of the LAD.

The most common causes of sudden cardiac death can be grouped into five categories: coronary disease, myocardial pathology, functional disease, pathology of the great vessels and miscellaneous, i.e., myxoma, cardiac metastases, or pericardial effusion/tamponade[7, 8]. Congenital anomalies of coronary artery number and course are part of the first category and can be classified on the basis of their origin, course, size, and termination[1, 9]. According to the guidelines published by the Association for European Cardiovascular Pathology, a diagnosis of sudden cardiac arrest is supported only by a post-mortem finding of coronary artery occlusion[10]. Therefore, in the presence of non-atherosclerotic acquired coronary artery diseases, a definitive diagnosis of sudden death can be formulated only after a post-mortem finding of coronary dissection or vasculitis complicated by occlusive thrombosis[11]. Congenital anomalies of the coronary arterial anatomy could however be identified as the real cause of sudden death when the tributary myocardium exhibits an acute infarct or post-infarction scar[11].

Notably, in the case we presented, there was a correspondence between the myocardial area affected by acute ischaemic damage (i.e., the anterior interventricular septum) and the absence of septal branches in the proximal segment of the LAD. Apart from this anomaly, the coronary arteries were perfectly normal in origin, course, size, and lumen patency.

Angelini et al.[1] included the ectopic origination of the first septal branch in the classification of coronary anomalies observed in normal human hearts. Dabizzi et al.[12] reported the absence of the first septal branch in a patient suffering from tetralogy of Fallot with a single coronary ostium or LAD arising from the RCA; in these cases, angiography showed that the interventricular septum had a blood supply similar to other individuals.

To our knowledge, no cases of sudden death in the presence of the anomaly presented in this publication have been reported. As demonstrated by Dabizzi et al.[12], in our case, the septum could have been supplied by an aberrant arising septal branch. Whatever the case may be, this vessel was not macroscopically identified. However, the amount of blood delivered was so small that it was impossible to satisfy the tissues’ blood request. In fact, histology identified signs of both chronic and acute myocardial ischaemic damage.

Arrhythmogenic right ventricular cardiomyopathy was excluded according to the absence of myocyte loss, fibrofatty replacement, and chronic inflammatory infiltrates[13].

The clinical history, autopsy, and histological results suggest arrhythmic sudden cardiac death triggered by myocardial ischaemia due to the absence of any anterior septal perforator branch in the proximal segment of the LAD.

In conclusion, we believe that this case is of potential interest for pathologists and coronary angiographers and interventional cardiologists. In fact, the agenesis or the ectopic origin of the anterior septal branches can be considered as a potential source of sudden death or cause of death. Moreover, when no other significant autopsy findings are present, particularly in the absence of risk factors and pathological findings directly related to the death, this anatomical variant should be considered. Finally, this case could be useful to autopsy pathologists in detecting this infrequent anomaly, thus providing a more accurate estimation of its incidence.

The authors declare that the present case-report has been carried out in compliance with the Helsinki Declaration (http://​www.​wma.​net/​en/​30publications/​10policies/​b3/​).