The Role of Ramus Intermedius in Atherosclerosis Plaque Deposition at the Left Bifurcation Region: A Retrospective Study using Coronary Computed Tomography Angiography

Abstract

Abstract Ramus intermedius (RI) is a coronary artery anatomical variant arising from the left main bifurcation angle coursing between the left anterior descending and left circumflex arteries. RI is commonly reported in coronary artery investigations, but its role in coronary artery disease (CAD) is unknown. The objective of this study is to evaluate the contributory effects of the RI in the development of CAD at the left bifurcation region (LBR) using coronary computed tomography angiography (CCTA). A retrospective cross-sectional single-centre study was conducted on patients who underwent CCTA from January 2017 until December 2018. A total of 374 patients were included based on inclusion and exclusion criteria. The left main coronary artery (LMCA), proximal left anterior descending (pLAD), and proximal left circumflex (pLCx) arteries were analysed against known cardiovascular risks (CVR) (i.e., Absence or Presence). The RI was identified in 32% of patients (n = 121). RI singularly increases the risk for plaque deposition at the LMCA and pLAD but not in the pLCx. RI increased the risk for LMCA stenosis by eight-fold (Adjusted OR, aOR: 8.5, 95% CI: 1.7, 43.0, p = 0.010). At the pLAD, a RI increased the risk for plaque deposition at the lateral wall by three-fold (aOR: 3.5, 95% CI: 1.1, 11.3, p = 0.036) and four-fold for plaque formation on both lateral and medial walls (aOR: 4.3, 95% CI: 2.7, 17.2, p = 0.038). These findings suggested for the first time that RI pose an elevated risk for atherosclerosis in coronary arteries.