Abstract 16364: Presence of Ramus Intermedius Artery is Associated With Higher Atherosclerotic Plaque Burden in the Left Main Stem in Coronary CT Angiography

Abstract

Introduction: Ramus intermedius (RI) is a variant vessel arising from left main (LM) bifurcation that supplies the lateral wall. It is thought that presence of RI would result in increased coronary turbulence in LM which in return could affect atherosclerotic plaque formation process. We aimed to investigate the association of presence of RI with presence of atherosclerotic plaque and stenosis in left main (LM). Hypothesis: Presence of RI artery associates with higher frequency of atherosclerotic plaque formation in LM Methods: We performed a large retrospective single-center study, including consecutive subjects who completed a CTA exam from October 2006 to December 2022 in Los Angeles, California to determine if presence of RI associated with higher LM coronary plaque burden. Chi-Square test was used to examine level of left main plaque burden and percent stenosis in subjects where the Ramus is present versus absent. Results: Among the 11,497 subjects, the average age was 62.0±12.4 years, 64% male, and 11% had the Ramus segment present. Those with a Ramus segment present were more likely to have mild, moderate or severe plaque burden (41% versus 26%, p=<0.0001) in their left main. (Table 1). Additionally, subjects with RI has higher prevalence of any degree of LM stenosis compared to those without RI (P-Value<0.0001). Conclusions: Our results suggest that the presence of RI is associated with higher prevalence of atherosclerotic plaques and higher degree of stenosis in LM stem.