ORIGINAL ARTICLE Absent Left Main Coronary Artery with Variation in the Origin of its Branches in a South African Population N. O. Ajayi 1 , L. Lazarus 1 , E. A. Vanker 2 and K. S. Satyapal 1 * Addresses of authors: 1 Department of Clinical Anatomy, School of Laboratory Medicine and Medical Sciences, College of Health Sciences, University of KwaZulu-Natal, Westville Campus, Private Bag X54001, Durban 4000, South Africa; 2 Chelmsford Medical Centre 3, St Augustine’s Hospital, 107 Chelmsford Rd, Durban 4001, South Africa *Correspondence: Tel.: + 27 31 260 7899, + 27 83 777 8780; fax: + 27 31 260 7890; e-mail: satyapalk@ukzn.ac.za With 5 figures and 2 tables Received March 2013; accepted for publication January 2014 doi: 10.1111/ahe.12109 Summary Coronary artery anomalies are traditionally classified into anomalies of origin, course and termination. One of the anomalies of origin is absence of the left main coronary artery (LMCA), where the left anterior descending (LAD), the circumflex (Cx) and the ramus medianus (RM) (when present) arteries originate directly from the left aortic sinus. The study aimed to document the prevalence of absent LMCA, discuss its possible embryogenesis and clinical rel- evance. A review of 407 coronary angiograms performed by cardiologists of three private hospitals in the eThekwini Municipality area of KwaZulu-Natal, South Africa, was performed. The LMCA was absent in 9.6% (39/407) of the coronary angiograms. The LAD and Cx arteries originated directly from the left aortic sinus with a single ostium in 8.6% (35/407) and separate ostia in 1% (4/407) of the angiograms. In four of the angiograms with absent LMCA, a RM artery was recorded originating directly from the left aortic sinus in addi- tion to the LAD and the Cx arteries. Angiographic detection of the anomalies of the coronary arteries is essential in the determination of the significance of such findings and their management. Introduction Coronary artery anomalies have been classified tradition- ally into anomalies of origin, course and termination (Majid et al., 2011). Clinically, coronary artery anomalies have also been classified as either lifethreatening or not (Danias et al., 2001) depending upon their prognosis (Yamanaka and Hobbs, 1990). The anomalies of origin include multiple ostia, single coronary artery, absence of the left main coronary artery, anomalous origin of the cor- onary artery from the pulmonary artery and origin of the coronary artery or branch from the opposite or non-coro- nary sinus or from the subclavian artery (Monro et al., 1978; Safi et al., 2001; Khanna et al., 2005; Kim et al., 2006; Li et al., 2011). The anomalies of course include myocardial bridging and duplication of arteries, and the anomalies of termination include coronary artery fistula, coronary arcade and extra cardiac termination (Kim et al., 2006). The anatomy of the coronary vasculature should be adequately evaluated preoperatively for the presence of coronary artery anomalies to avoid transsection, ligation or iatrogenic obstruction of vessels (Hobbs et al., 1981). As noted earlier, one of the anomalies of origin is the absence of the left main coronary artery (LMCA), where the left anterior descending artery (LAD) (also called the anterior interventricular artery), the circumflex (Cx) artery and ramus medianus (RM) artery (when present) originate directly from the left aortic sinus. This anomaly is sometimes not recognized at the time of catheteriza- tion, and the LAD or Cx artery may be misinterpreted as totally obstructed, atretic or congenitally absent (Yama- naka and Hobbs, 1990; Cankaya et al., 2009). The absence of the LMCA has no adverse hemodynamic consequence (Kos ßar et al., 2009), but may cause technical difficulties in coronary artery catheterization and result in misdiag- nosis (Cankaya et al., 2009) or may be a source of com- plication during diagnostic, interventional and surgical procedures (Kos ßar et al., 2009). The absence or early bifurcation of the LMCA may cause perioperative occlusion of a main branch of the © 2014 Blackwell Verlag GmbH Anat. Histol. Embryol. 44 (2015) 81–85 81 Anatomia, Histologia, Embryologia