Teaching Case

The patient was referred by the GP to the ED for thoracic pain irradiating to the left arm.
There were multiple cardiovascular risk factors (arterial hypertension, hypercholesterolaemia, 7 pack-years, positive family history).

A clinical question: Stenosis?

Rare congenital variant: mono coronary originating from the non-coronary cusp.
The left anterior descending coronary artery (LAD) courses from the right atrioventricular (AV) groove anterior of the pulmonary trunk to the anterior interventricular groove (prepulmonic course).
The left circumflex coronary artery (LCx) courses posterior to the aorta from the right AV groove to the left AV groove (retro-aortic course).
No interatrial "malignant" course. No acute angle takeoff, slitlike orifice nor an intramural segment. No significant coronary stenosis.

A. Multiple courses of anomalous origin of the coronary artery from the opposite sinus (ACAOS) are known: retro-aortic, prepulmonic, transseptal and interarterial. [1]
Of these four variants, only the interarterial course is a cause of sudden cardiac death (SCD), the exact pathophysiology is not elucidated, because a normal pulmonary artery is not likely to exert enough pressure to occlude an interarterial coronary artery. [2] Right ACAOS is more frequent than left ACAOS, but has a weaker association with SCD.
An intramural segment, another associated anatomical variant, is probably the most predisposing factor to sudden cardiac death. [3]
It is defined as a proximal segment of the coronary artery located in the 'media' of the aortic wall without an intervening adventitia. [4]
B. Ischaemia (and possibly SCD) occurs when expansion of the great vessels during exercise leads to occlusion of the slitlike ostium and stretching of the acute course of the coronary artery. [2]
The onset of symptoms later in life is related to the development of hypertension, aortic root dilatation and increased stroke volume. [5]
C. Key findings are a slitlike orifice, an acute angle takeoff and a stretched intramural segment.
CT angiography is the examination of choice for detection of an intramural segment due to the multiplanar capabilities. An abnormal elliptical cross section proximally (height-to-width ratio greater than 1,3) with normal round luminal shape more distally allows diagnosis of an intramural segment. [6]
D. In our case biochemistry showed negative troponins and D-dimer tests, ECG showed anteroseptal QS pattern with slight J-point elevation in V1-V3 and echocardiography showed normal LV and RV contractility and function, slight mitral and tricuspid regurgitation.
No arguments for active cardiac ischaemia were retained and low dose acetylsalicylic acid (ASA) was prescribed. Elective CT angiography was planned because of the suspicious symptoms and cardiovascular risk factors. Since there was no malignant course and no coronary calcifications or stenosis, acetylsalicylic acid was ceased. The symptoms were thought to be related to coronary spasm and a calcium channel blocker was prescribed if symptoms would recur.
E. Describe anatomic variants (ACAOS and interarterial course). Search for a slitlike orifice, acute angle of origin and intramural segment because these carry an even higher risk of sudden cardiac death and the latter can be treated with coronary unroofing. [7]