Thread by @ashaukat09

Another #FITSurvivalGuide tweetorial. This time on #intracoronary imaging w/ focus on IVUS and OCT
➡️ Rationale for use
➡️ Tech basics
➡️ Uses
➡️ Data
➡️ Images (high-yield)
➡️Comparison
@z_alirhayim @Almanfi_Cardio @AntoniousAttall @abashirMD @Babar_Basir

Why use them?
- Cor angio limited by: 2D view of 3D artery, diffuse dx, foreshortening, angulations, Ca++, eccentricity, vessel overlap, contrast streaming
- Angio alone ➡️ undetected edge complications, suboptimal stent exp in 15-20% ➡️ adverse events @cardiojaydoc02

IVUS tech: US reflected from vessel wall
➡️ 2 types: Rotational; Phased-array
➡️Rotational: 40-45 MHz, 3.2 Fr, 5 Fr guide, Rx, better near field resolution
➡️Phased-array: 20 MHz, 3.5 Fr, 5 Fr guide, Rx, more trackable
➡️Co-registration with angio now available

OCT:
➡️ Uses near infrared 🔦, principles of US
➡️ 2.4-2.8 Fr
➡️ Imaging core at distal tip at 90 degrees to vessel, Rx, automated pullback, co-registration
➡️ Cannot penetrate blood cells - needs contrast flush
➡️ 10 x ⬆️ resolution but less imaging depth vs. IVUS

IVUS uses: ✅ lumen and vessel 📏, extent/severity of dx, remodeling, plaque burden, Ca
Non-LM lesions: Correlation with FFR modest (~60%), variable cutoffs, ❌ recommended to decide PCI vs not.
IVUS-XPL trial – 1400 pts with ≥ 28 mm lesions: ⬇️ TLR
CTOs: ⬇️ MACE, ISR, ST

IVUS in LM – 💯
❓ with Cor angio: short, Ca++, diffuse dx, bifurcation, ostial
✅ Can defer PCI if MLA ≥ 6 mm2 (if <, consider FFR)
➡️ EXCEL subanalysis: ⬇️ MSA : ⬆️ MACE, death, MI, ST at 3 yrs
➡️ Meta-analysis of 4592: ⬇️ MACE, death, MI and ST.
✅ ACC/AHA + SCAI

Pre-PCI: reference lumen, lesion📏 (stent📏), landing zone, Ca++ (?atherectomy), large thrombus (?thrombectomy), dissection (?SCAD)
Post-PCI: detect comps, suboptimal stent deployment/expansion/apposition, edge dissections, incomplete lesion coverage, tissue protrusion, thrombus

IVUS + PCI: ⬇️ MACE (mainly ⬇️ TLR), ⬇️ ST (1st and 2nd gen DES)
2nd gen DES: ⬇️ MACE, ⬇️ MI
✅ BMS, 1st + 2nd gen, ✅✅ longer lesions.
But, IVUS used in ~20% in USA
Best to use when: ❓underexpansion, long, ❓reference size, Ca, LM, complex anatomy, CTOs.

OCT uses: incomplete stent expansion, stent fracture, incomplete coverage
Better than IVUS for:
Plaque type
🧐 thrombus and type (red - RBCs/white - plt)
Small stent malappositions
Edge dissections
Tissue prolapse
Neo-intima formation and characteristics

But ❓clinical and long-term implications of findings
Other uses of OCT:
-🧐 culprit in ACS (thrombus, plaque rupture, erosion, Ca nodules, SCAD, embolic)
- Stent surveillance: neointima, neoatherosclerosis, mechanism of ST
- IVUS better for plaque burden (⬆️depth)

OCT + PCI: Plaque type (fibrous/lipid vs Ca) ➡️ lesion prep (atherectomy vs. 🎈)
Ca area correlates with stent underexpansion
PCI optimization:
-co-registration (stent edge landing zones, stent 📏)
-targeted post-dil of underexpanded stent segments
-“❌ contrast” PCI in CKD

OCT v IVUS
⬇️ data
⬇️ MLA thresholds
⬇️ studies of clinical outcomes vs FFR, esp in LM
- MLA correlation with FFR modest
- TCFAs ➡️ peri-PCI MI (ILUMIEN – ⬇️ peri-PCI MI with OCT)
- ILUMIEN 3: 450 patients (1:1:1) OCT non-inferior to IVUS and Cor angio
- ACC/AHA: ❓

Future: ILUMIEN IV: OCT vs angio, clinical outcomes, 2500 patients (high clinical or angiographic risk). Primary outcome: TVF
Barriers to use:
➡️ availability
➡️ 💰
➡️ ❌ reimbursement
➡️ adequate training
➡️ ⏲️
➡️ contrast
But, "a picture is worth 1000 words"!