Association of Ramus intermedius with increased atherosclerotic plaque in the left main stem.

Ramus intermedius (RI) is a variant vessel from the left main (LM) stem bifurcation that supplies the lateral wall. It is thought that the presence of the RI would increase coronary turbulence in LM, which could affect the atherosclerotic plaque formation process. We aimed to investigate the presence of RI with atherosclerotic plaque and stenosis in the LM. We performed a large retrospective single-center study, including 11,497 subjects who completed a CTA exam from October 2006 to December 2022 in Los Angeles, California. The presence of an RI was assessed by expert reviewers. Bivariate analyses were conducted using Chi-square test to compare plaque burden and stenosis between those with and without an RI. Multivariable logistic regression was performed to evaluate association between the presence of RI and LM plaque, adjusting for traditional cardiovascular risk factors including age, sex, ethnicity, BMI, hypertension, diabetes, dyslipidemia, and smoking status. Among the 11,497 subjects, the average age was 62.0 ± 12.4 years, 64% were male, and 11% had an RI present. Individuals with an RI were more likely to exhibit any plaque burden in the LM stem compared to those without the variant (41% vs. 26%, p < 0.001). They also had a higher prevalence of LM stenosis of any degree (p < 0.001). In a multivariable logistic regression model adjusted for traditional cardiovascular risk factors, the presence of RI remained significantly associated with the presence of LM plaque (OR 1.71 [1.51-1.95], p < 0.001). Our results suggest that the presence of RI is associated with a higher prevalence of atherosclerotic plaque and a higher degree of stenosis in the LM stem.