Objective: To describe coronary artery anomalies (CAAs), with emphasis on clinically significant variants, and to highlight their association with sudden cardiac death (SCD), particularly in young individuals. Materials and Methods: A descriptive overview based on existing clinical observations and literature regarding the anatomical variations of coronary artery origin and course, with particular focus on anomalies involving origin from the opposite sinus of Valsalva and their clinical implications. Results: Most CAAs were found to be benign and incidentally detected during cardiac catheterization. However, anomalies involving the origin of a coronary artery from the opposite sinus demonstrated significant clinical relevance. The interarterial course, where the artery passes between the aorta and pulmonary artery, was identified as the most critical (“malignant”) variant, showing a strong association with an increased risk of SCD, especially in younger patients. Conclusion: While the majority of CAAs are benign, certain variants—particularly those with an interarterial course—carry a high risk of sudden cardiac death. Early recognition and appropriate evaluation of these anomalies are essential for risk stratification and prevention of adverse outcomes.
Coronary artery anomalies (CAAs) are described as congenital variations in the coronary arteries- involving either the origin or their course . Most of these anomalies of the coronary artery are asymptomatic and are discovered incidentally on either performing conventional angiography or on CT angiography [1]. The other presentation is noted in the younger patients who usually present in the first three decades of life with ischaemic cardiac event post strenuous physical activity.(2)
The coronary artery anomalies can be divided into different categories depending upon the origin and the course of the coronary arteries such as retroaortic, interarterial, subpulmonic (intraconal or intraseptal), prepulmonic, or retrocardiac variants. However the anomaly involving the origin of the respective coronary artery from the opposite sinus is the most significant.(3,4)
Anomalous origin of the left coronary artery from the right aortic sinus is rare with an estimated prevalence of 0.02–0.05% [5]) It is amongst the leading causes of sudden cardiac death in the younger age group, with the interarterial variant( also called the malignant variant) having the highest risk.
A 46-year-old female with no relevant medical history presented with 2 episodes of syncope occurring within 24 hours. The first episode occurred while sitting at home. Husband did CPR and she was revived. The second episode occurred in emergency department of a hospital. The monitor strip showed a (Ventricular tachycardia) VT. She was revived successfully. Holter revealed runs of non-sustained VT. Her physical exam, electrocardiogram and echocardiogram were unremarkable.
Since she was considered to have low likelihood of coronary artery disease (CAD), she was referred for a cardiac CT. The CT angiogram showed a variant anatomy. There was an anomalous origin of left coronary artery(LCA) arising from the right coronary cusp which followed an interarterial course, (Fig.1). LCA coursing through right ventricular outflow tract.(Fig 2) The coronary arteries were disease free. Stress Thalium scan was done which was negative for inducible ischemia. Electrophysiologic study done did not induce a VT. Subsequently she underwent AICD implantation in view of resuscitable SCD.
There are numerous kinds of CAAs; which are further subdivided into different categories according to their site of origin, their course, and eventually their termination.
The most important variant is the origin of the coronary artery from the opposite cusp, while of the coronary arteries from the non coronary sinus is rare (2). These anomalies have usually no known association with any congenital abnormalities.
Coronary arteries can have anomalous origins and courses. The left main (LMC) or left anterior descending coronary artery (LAD) can originate from the right or non-coronary cusps of the ascending aorta. The “benignity” or “malignancy” of such anomalous origins depends on the subsequent course of the vessel. Depending upon the course of the left coronary artery they can be divided into four main categories- these are the interarterial course; septal course, anterior course and retroaortic course. The interarterial course is a cause of sudden cardiac death, immediately after vigorous exercise or any strenuous activity.(6) The angle of origin of the coronary arteries could offer a possible explanation. The normal coronary arteries arise at right angles from the respective coronary cusps; while the anomalous arteries arise at an acute angle- making it susceptible to ischaemia. Another explanation is due to the anomalous course, while exercising or carrying out strenuous work, increased flow in the aorta and pulmonary arteries would compress the vessel coursing between these two vessels.
The management in these cases are controversial with no universally accepted line of management .The younger patients are advised either lifestyle modifications in terms of avoiding strenuous work, exercise or games. These patients would require an annual follow up with either a thallium scan or stress echocardiogram. In patients who are aged more than 35 years, the risk of suffering cardiac death decreases significantly. In patients who require further management -surgical revascularisation or percutaneous intervention, with implantation of stents in the region of the compression are possible alternatives.
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