Key result
Presence of a ramus intermedius is linked to a ~30° wider LAD-LCX bifurcation angle.
Why the study?
Ramus intermedius changes the left main coronary division from a bifurcation to a trifurcation, but its associations with left main geometry, CT-FFR, and adjacent-vessel atherosclerotic features remain incompletely characterized.
Does the presence of a ramus intermedius alter left main coronary bifurcation geometry (specifically the LAD-LCX angle), vessel dimensions, plaque features, and CT-FFR in adults undergoing clinically indicated CCTA?
Cohort (n=300)
The observer who performed anatomic measurements and CT-FFR analysis was blinded to recorded clinical variables during image processing.
No
Does the presence of a ramus intermedius alter left main coronary bifurcation geometry (specifically the LAD-LCX angle), vessel dimensions, plaque features, and CT-FFR in adults undergoing clinically indicated CCTA?
Presence of a ramus intermedius is associated with a ~30° wider left main bifurcation angle and larger left main dimensions on CCTA, and an RI ostium arising proximal to the LAD is associated with smaller LAD cross-sectional area and more frequent LAD CT-FFR positivity.
Answers are grounded in this paper and cite their sources.
Ramus intermedius was associated with wider LAD-LCX angle; hypothesis-generating for impacts on plaque and CT-FFR in CCTA cohorts.
Background Ramus intermedius (RI) changes the left main (LM) coronary division from bifurcation to trifurcation, but its associations with LM geometry, CT-derived fractional flow reserve (CT-FFR), and adjacent-vessel atherosclerotic features remain incompletely characterized. Methods In this retrospective single-center study, consecutive adults who underwent clinically indicated coronary computed tomography angiography between December 2024 and April 2025 were screened. The final age-matched cohort included 300 patients (150 with RI and 150 without RI). LAD-LCX angle, vessel diameter and cross-sectional area (CSA), plaque features, stenosis severity, and CT-FFR were evaluated. RI-specific analyses by ostial location, diameter, and functional status were exploratory. Benjamini-Hochberg false-discovery-rate correction was applied within prespecified outcome families. Because sex distribution differed between groups, the primary LAD-LCX angle comparison was supplemented by an aggregate tipping-point sensitivity analysis. Results Patients with RI had a wider LAD-LCX angle than patients without RI (99.35° ± 25.61° vs. 69.22° ± 17.83°; P < 0.001), with a mean difference of 30.13° (95% CI, 25.11°-35.15°), and had larger LM diameter and CSA. Diseased-segment analyses showed no significant between-group differences in plaque composition or stenosis severity. Within the RI group, proximal-LAD RI origin remained associated after multiplicity correction with smaller LAD CSA (q < 0.008) and more frequent LAD CT-FFR positivity (q = 0.009), whereas nominal anatomic stenosis signals were attenuated (q = 0.051). Only 10 patients had RI CT-FFR ≤ 0.80; findings stratified by RI CT-FFR status were therefore presented descriptively. In the aggregate sensitivity analysis, a male-female LAD-LCX angle difference of approximately 105.1° would be required for the observed sex imbalance alone to reduce the primary group contrast to zero, but this calculation does not replace patient-level adjustment. Conclusions RI presence was associated with a wider LM bifurcation angle and larger LM dimensions on CCTA. Selected RI ostial-location associations persisted after multiplicity correction. These observational findings do not establish causality, and residual confounding and the sparse RI CT-FFR-positive subgroup warrant cautious interpretation and external validation.
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Lv et al. (2026) conducted a cohort in Clinically indicated coronary computed tomography angiography evaluation for coronary anatomy and disease (n=300). Ramus intermedius (RI) presence (diameter ≥ 2 mm on CCTA) vs. Absence of ramus intermedius (1:1 age-matched) was evaluated on LAD-LCX take-off angle at the left main bifurcation (degrees) (MD 30.13°, 95% CI 25.11-35.15, p=<0.001). Ramus intermedius presence was associated with a wider LAD-LCX bifurcation angle compared to absence of ramus intermedius (99.35° vs 69.22°; MD 30.13°, 95% CI 25.11-35.15, P<0.001).
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