Which coronary artery branch contains the 80% mid‑ramus lesion adjacent to the proximal ramus stent placed with a Synergy drug‑eluting stent during percutaneous coronary intervention?

Ramus Intermedius Branch

The 80% mid-ramus lesion adjacent to the proximal ramus stent is located in the ramus intermedius (or ramus intermedius artery), which is a distinct coronary branch that arises from the left main coronary artery between the left anterior descending (LAD) and left circumflex (LCX) arteries.

Anatomical Context

The ramus intermedius is a variant coronary anatomy present in approximately 15-30% of patients. When present, it:

• Originates directly from the left main coronary artery as a separate vessel
• Courses between the LAD and LCX territories
• Supplies the lateral wall of the left ventricle
• Is considered a major epicardial vessel when of sufficient caliber (typically ≥2.0 mm diameter)

The evidence references this anatomy explicitly 1, 2, with specific mention of "saphenous vein grafts to the ramus intermedius" in coronary imaging guidelines, confirming its recognition as a distinct coronary branch.

Clinical Significance of Your Lesion

Your patient has:

• Proximal ramus: Previously stented with Synergy drug-eluting stent
• Mid ramus: New 80% stenosis adjacent to (distal to) the proximal stent

This represents in-segment restenosis or disease progression in the ramus intermedius territory.

Management Considerations

Given the 80% stenosis adjacent to an existing stent, this lesion warrants intervention. The 2018 ESC guidelines 3 recommend:

• Dual antiplatelet therapy (DAPT) for 12 months post-PCI with potent P2Y12 inhibitors (prasugrel or ticagrelor preferred over clopidogrel) unless excessive bleeding risk
• Intravascular imaging guidance is particularly valuable for stent optimization in complex scenarios involving adjacent stented segments 4

Key Technical Points

When treating lesions adjacent to existing stents:

• Avoid geographic miss (incomplete lesion coverage)
• Ensure adequate stent overlap (typically 2-4 mm) if extending the stented segment
• Use intravascular ultrasound (IVUS) or optical coherence tomography (OCT) to assess stent expansion, apposition, and edge dissection 4
• Target minimum stent area >5.5-6.0 mm² for non-left main vessels 4

Common pitfall: Stenting into reference segments with plaque burden >50% increases risk of edge dissection and restenosis 4. Ensure adequate lesion preparation with pre-dilatation, especially if calcification is present.

The Synergy stent platform has demonstrated favorable outcomes in bifurcation and complex lesions 5, 6, making it appropriate for this ramus anatomy.