A case report of an atypical hyper-dominant left anterior descending artery with a sac that misleads a stump-less chronic total occlusion.

The prevalence of coronary artery anomalies ranges from 0.3% to 5.6% in studies on patients undergoing coronary angiography. The left anterior descending artery (LAD) continuing as posterior descending artery (PDA) is termed as ‘hyper-dominant LAD’ or ‘super-dominant LAD’. Jariwala et al. had reviewed only 17 reports of the hyper-dominant LAD until 2018.

Here, we present a case of a patient who was found to have an atypical hyper-dominant LAD with an unusual long course that continued across the left ventricular apex as a PDA, thereafter formed into a sac after supplying the area of the diaphragmatic surface of the left ventricle (; Video 1). Due to the existence of the bulging sac, the wrapping PDA was mistaken for a collateral branch. In addition, a continuation of the LAD (distal-LAD) at the distal portion of the sac was visualized by the microcatheter angiography, which was also misinterpreted as the distal segment of the occluded vessel (; Video 2). Originally, we speculated that this may be a stump-less chronic total occlusion (CTO). The intravascular ultrasound was used to identify entry channels into CTO lesions. Yet, no obvious disruption and proximal stump in the right coronary artery was observed (Video 3). For a more accurate understanding of the vessel anatomy, coronary computed tomographic angiography (CCTA) was performed to visualize the coronaries. CCTA with three-dimensional reconstructions showed an unusual long course of the LAD, which wrapped around the apex of the heart, continued as a PDA up to the crux of the heart, thereafter formed into a sac after supplying the area of the diaphragmatic surface of the left ventricle, then terminated in the posterior atrioventricular groove ().

Figure 1

The simultaneous angiogram of the left and right coronary systems (A, B). The computed tomographic angiography displayed three-dimensional vessel trajectories (C–F). (A) An unusual course of the left anterior descending artery (blue dashed), which coursed towards the right coronary artery, terminating as a sac (arrow, white) after supplying the area of the diaphragmatic surface of the left ventricle (cranial). (B) The vessel (distal-left anterior descending artery) at the distal end (yellow dashed) of the sac (arrow, white) was visualized by injection through the microcatheter (right anterior oblique-cranial). (C–F) The left anterior descending artery wrapped around the apex of the heart, continued as a posterior descending artery up to the crux of the heart, thereafter formed into a sac (arrow, white, C–F) after supplying the area of the diaphragmatic surface of the left ventricle, then terminated in the posterior atrioventricular groove (arrow, yellow, C–F). No obvious stenosis, calcification, and proximal stump were detected in the right coronary artery. No other coronary ostia were found in the sinuses of Valsalva. CCTA, coronary computed tomographic angiography; LAD, left anterior descending artery; LV, left ventricle; PDA, posterior descending artery; RAO, right anterior oblique; RCA, right coronary artery.