Unique Coexistence of Dual Left Anterior Descending Artery and Split Right Coronary Artery

A 50-year-old male presented in the outpatient clinic with a history of chronic coronary syndrome with class III angina on exertion. Electrocardiogram (ECG) showed ST elevation with positive cardiac biomarkers. He was taken for primary percutaneous coronary intervention (PCI), which revealed an unusual coronary arterial anatomy. Severe diffuse disease was seen in the shorter left anterior descending artery (LAD) and proximal ramus intermedius. Right coronary artery (RCA) angiogram revealed a longer LAD arising from the proximal RCA coursing towards the anterior interventricular groove reaching to the cardiac apex. The RCA appeared to split into two branches of equal size, both reaching the posterior interventricular groove. No stenosis was seen in the RCA branches (Figure 1). In light of the disease-free longer LAD supplying the left ventricular myocardium, no active intervention was done at the time.

Figure 1

Subsequently, an ECG-gated coronary computed tomography angiography (CCTA) was performed for delineation of the coronary anatomy. CCTA showed the presence of type IV dual LAD, with the severely diseased shorter LAD arising from the left main coronary artery and a longer LAD arising from the right coronary artery having pre-pulmonic course to enter the anterior interventricular groove, reaching to the cardiac apex.1 The RCA was seen trifurcating shortly after its origin into the longer LAD and two other branches (anterior and posterior) of almost equal calibers. The posterior branch was seen coursing orthotopically within the right atrioventricular (AV) groove, reaching until the crux of the heart and terminating as the proximal posterior descending artery (PDA). The anterior branch exited the right AV groove and was seen coursing along the acute margin of the heart, giving off the acute marginal branch. The anterior branch subsequently terminated in the distal half of the posterior interventricular groove to terminate as the distal PDA (Figure 2).

Figure 2

Split RCA is a rare anatomical variant wherein the RCA divides into anterior and posterior divisions subsequently terminating as two PDA.2, 3 Coexistence of dual LAD with split RCA is rare, with no similar cases reported in literature to date. This case underscores the importance of CCTA in accurately delineating rare coronary artery anatomical variants to avoid both a misdiagnosis and the risk of potential catastrophic outcomes during interventional or surgical procedures.