Anomalous Origin of the Left Coronary Artery from the Right Aortic Sinus with a Subpulmonic Intramyocardial Course: Malignant Anomaly or Benign Variant?

Objectives: Anomalous aortic origin of a coronary artery (AAOCA) is a rare congenital abnormality, which may be associated with increased risk of myocardial ischemia, life-threatening arrhythmias or sudden cardiac death. This refers specifically to AAOCA associated with interarterial and/or intramural course. Much less is known about anomalous origin of the left coronary artery from the right aortic sinus associated with subpulmonic intramyocardial course.

Case Report: We report a 12 year old girl who complained of recurrent episodes of chest pain lasting for some minutes and not associated with exercise. Echocardiography at the age of 8 years had shown AAOCA of the left coronary artery from the right aortic sinus. The diagnosis was confirmed at the age of 12 years by CT-scan and selective coronary angiography. The LCA originating from the right sinus took a subpulmonary intramyocardial course within the conal septum. Treadmill test, stress echocardiography, cardiac MRI and Holter revealed no evidence of myocardial ischemia. We opted in this patient for a conservative approach with regular follow-up visits.

Discussion: In adulthood AAOCA of the left coronary artery from the right aortic sinus taking a subpulmonic course has been described with a higher prevalence than the respective anomaly associated with an interarterial course. It was found in 8/110 coronary arteries originating from the opposite sinus as compared with 2 cases of left coronary artery associated with an interarterial course (Cheezum et al. EHJ Cardiovasc Imag 2017:18;224). Although in AAOCA with subpulmonic course the LCA is subject of potential myocardial compression during systole, this appears to be associated with less clinical problems than AAOCA of the LCA with an interarterial course. Therefore AAOCA with subpulmonic course of the LCA has been addressed as generally benign. Nevertheless several cases of these patients requiring surgery due to myocardial ischemia have been described in two recent series addressing treatment in AAOCA (Cheezum et al, EHJ Cardiovasc Imag 2017:18;224; Mainwaring et al, Eur J Cardio-Thorac Surg 2014:46;20). Therefore, we recommend to follow up these patients closely for possible myocardial ischemia during exercise.

Conclusion: AAOCA with subpulmonic course of the LCA is a rare but not uncommon anomaly that is benign in the majority of cases. Careful follow-up seems reasonable however, since some of these patients may develop significant clinical problems.