“We cross, stent, and follow up against a shadow. The plaque that causes the next heart attack is the one the angiogram never showed.”

Angiography is a lumenogram, a shadow of the channel, and it is reliably outmatched by intravascular imaging where outcomes are decided. Across randomized trials, imaging-guided PCI lowers major adverse cardiac events compared with angiography alone; a 2024 meta-analysis put the difference at roughly 8 percent versus 13 percent,^[1] and a large 2023 trial showed the same advantage in complex lesions.^[2] The reason is plain: decisions improve when the operator can see the lesion rather than its silhouette.

The one axis today’s tools cover least well is the forward one, the tissue and path directly ahead of the device, inside the lesion, where the operator is actually working. What follows is a map of the places where seeing that clearly changes the decision. Each entry pairs an established clinical fact from the intravascular imaging literature with the decision a forward view would inform. One scope note in the interest of honesty: most of the evidence cited comes from side-viewing IVUS and OCT, and from the physics of light, optical imaging is attenuated by blood and operates in the lesion substance rather than down an open, blood-filled vessel.^[3] The claim here is not that a forward view has replicated these trials. It is that these are precisely the lesion features that change PCI decisions, and the forward axis is where they are currently hardest to see.

One: Reading What Is Causing the Occlusion

Disruptive (ruptured) atheroma.  A ruptured plaque with an exposed necrotic core and adherent thrombus is the classic acute culprit, and stenting blindly across it can push friable material downstream. Recognizing the rupture and the lipid burden ahead informs lesion preparation and embolic-protection choices instead of a blind deployment.^[4,5]

Acute and organized thrombus.  Thrombus is not plaque, and crushing it beneath a stent is rarely the right move. Histology shows recanalized channels through organized thrombus that permit crossing, ideally followed by thrombus management before modification and stenting.^[6] Seeing thrombus ahead changes the sequence of the case.

Calcified atheroma (sheet or concentric calcium).  Dense circumferential calcium will not yield to a balloon, and a stent dropped into it underexpands, raising stent thrombosis, restenosis, and target-vessel failure.^[7] Imaging-based calcium scoring is what tells the operator to modify first, with atherectomy or lithotripsy, and how aggressively to do it.^[8]

Calcified nodule.  A protruding calcified nodule is a distinct and under-recognized entity that disrupts the lumen, resists stenting, and reprotrudes through struts. In registry follow-up, eruptive nodules carried roughly a 20 percent rate of cardiac death or target-lesion infarction versus under 3 percent for non-eruptive,^[9] so distinguishing the two ahead of treatment changes device selection.

Lipid-rich plaque and thin-cap fibroatheroma.  A large lipid core predicts distal embolization and periprocedural infarction; lesions with a high near-infrared lipid-core burden index have shown roughly a 50 percent risk of periprocedural MI versus about 4 percent for low-lipid lesions.^[10] Seeing the lipid ahead is a signal to slow down, size carefully, and consider protection.^[4]

Plaque erosion, the case that may need no stent.  When the fibrous cap is intact and the culprit is erosion rather than rupture, a subset of patients can be stabilized on antithrombotic therapy with no stent at all. The EROSION study showed this is feasible,^[11] and a randomized comparison cut stent use to about 44 percent versus 59 percent under angiographic guidance.^[12] This is the rare case where seeing clearly means doing less.

Two: Finding and Confirming the Path

True lumen versus extraplaque position.  The most consequential CTO misread is taking the extraplaque space for the true lumen. Consensus crossing algorithms are built around confirming position, and a forward view interrogates the trajectory the wire is about to take before it commits.^[13]

Microchannels, the natural opening.  Most CTOs, especially younger ones, contain intraluminal microchannels of roughly 100 to 500 microns that provide a crossing pathway,^[14] and a wire does best finding that path of least resistance rather than forcing a new one. Seeing the opening turns a blind probe into a targeted one.

Proximal cap ambiguity, blunt caps, and in-stent occlusion.  An ambiguous or blunt cap with no stump is where even expert operators are partly blind, and the algorithm routes these lesions to special handling.^[13] Older occlusions tend to be dense calcium without microchannels,^[15] a different problem the operator wants to recognize before committing to a strategy.

Three: Choosing the Device and the Landing Zone

Vessel and lesion sizing.  Selecting balloon and stent diameter and length from a shadow invites under- or oversizing. Imaging the true dimension supports correct device selection, which is part of why imaging-guided PCI outperforms angiography in randomized data.^[4]

Landing-zone selection.  A stent edge that lands in lipid-rich or diseased tissue is prone to edge dissection and restenosis. The principle is to land the edges in the most normal segment available, which requires seeing the tissue at the intended landing zone rather than guessing from the angiogram.^[4]

Four: The Ambiguous and the Dangerous

Spontaneous coronary artery dissection.  Angiography often cannot separate the true lumen from the false one or locate the intimal entry. Intracoronary imaging confirms wire position, localizes the breach, and frequently supports not stenting at all, since most spontaneous dissections heal conservatively.^[16] Wiring or stenting a false lumen is a catastrophe a clear forward view helps prevent.

In-stent restenosis mechanism.  Restenosis is not one thing. Neointimal hyperplasia, neoatherosclerosis, calcified neointima, and underexpansion each call for a different response, from drug-coated balloon to lithotripsy to re-stenting.^[17] Seeing the mechanism ahead selects the right treatment instead of repeating the failure.

Anticipating no-reflow and underexpansion before they happen.  The two most demoralizing results in PCI, a no-reflow vessel and an underexpanded stent, are often predictable from what sits ahead: a large lipid core for the first,^[10] dense unmodified calcium for the second.^[7,8] Forward characterization turns a post-hoc complication into a pre-empted one.

Five: After the Procedure

Confirming the stent was implanted as expected.  A stent that looks perfect on the angiogram is routinely underexpanded or malapposed on imaging, and that matters more than almost anything else the operator controls: minimal stent area is the strongest predictor of stent thrombosis and restenosis, and underexpansion is the most important correctable cause.^[18] Consensus puts the targets in numbers, a minimal stent area above roughly 4.5 square millimeters by OCT or 5.0 by IVUS, or relative expansion above 80 percent,^[18] and in the ILUMIEN IV trial imaging guidance achieved larger stent areas, with optimized dimensions associated with freedom from stent-related events.^[19] Seeing the result, edge dissection, apposition, tissue protrusion, and expansion, before leaving the table turns a hopeful deployment into a verified one.

Confirming it is still working over time.  When a stent fails, it fails for a reason imaging can name and angiography cannot: underexpansion, neointimal hyperplasia, stent fracture, or in-stent neoatherosclerosis, the regrowth of plaque inside the stent.^[20] Each calls for a different response, from a drug-coated balloon to calcium modification to re-stenting, and choosing among them on a follow-up study requires seeing the mechanism, not just the renarrowing.^[20] A forward, near-field view of the stented segment is aimed squarely at that question: not only whether the lumen has narrowed, but why.

The Aspiration: Toward a Preventive Standard of Care

Everything above happens once a patient is already in the laboratory for a known problem. The larger prize is earlier. Decades of natural-history work have shown that the plaques which cause future heart attacks are often not the tightest ones: high-risk features, a thin fibrous cap over a large lipid core, heavy plaque burden, a small lumen, predict events regardless of how narrow the artery appears.^[21] High-resolution and near-infrared imaging can identify those vulnerable plaques and the patients carrying them,^[22] and in 2024 the PREVENT trial became the first large randomized study to show that treating such non-flow-limiting vulnerable plaques, on top of optimal medical therapy, reduced cardiac events over two years.^[23]

That is the foundation of a larger vision: a forward-viewing intracoronary examination that does for the coronary arteries something like what colonoscopy did for colon cancer, finding and addressing the dangerous lesion, in the patients who warrant a look, before it becomes a heart attack or a stroke rather than after. The vision is worth stating plainly, and the distance still to travel is worth stating just as plainly. PREVENT was positive but debated, open-label, with event rates far lower than its designers assumed, and read by many experts as a signal rather than a license to seal every vulnerable plaque.^[23] And the colonoscopy analogy has a real limit, because coronary imaging today is invasive in a way screening colonoscopy is not. The credible near-term path is therefore the patient with the right risk profile, frequently one already undergoing catheterization, not the asymptomatic population at large.

So the honest destination is a staged one. First, see clearly during the procedures already being done: crossing, characterizing, sizing, optimizing, verifying. Then, see clearly in the patients whose risk justifies a look, to catch the lesion that would otherwise announce itself as an emergency. The through-line from the first entry on this map to the last is a single idea. Angiography shows the channel; the future of this work belongs to seeing the substance and the path directly ahead, early enough and clearly enough to change what happens next. The aspiration is not a better picture. It is a heart attack that never happens.

Field Notes is a personal series on the craft of interventional work and the tools that support it. Views are the author’s own, and nothing here is medical advice or a product claim.

References

1. Intravascular Imaging-Guided Versus Coronary Angiography-Guided Complex PCI: A Meta-analysis of Randomized Controlled Trials. Cardiol Ther. 2024. Intravascular imaging reduced MACE versus angiography (8% vs 13.3%; RR 0.63), with lower cardiac death, stent thrombosis, and revascularization. pubmed.ncbi.nlm.nih.gov/38630393

2. Intravascular imaging-guided or angiography-guided complex PCI (RENOVATE-COMPLEX-PCI). N Engl J Med. 2023;388:1668-1679. Imaging-guided PCI significantly reduced MACE versus angiography-guided PCI in complex lesions. pmc.ncbi.nlm.nih.gov/articles/PMC12254063

3. OCT/IVUS comparative reviews. Near-infrared light is scattered and absorbed by blood, so optical coronary imaging requires a blood-free field; ultrasound penetrates further but characterizes the wall beside the catheter. ahajournals.org/doi/10.1161/circulationaha.112.117143

4. Truesdell AG, et al. Intravascular Imaging During PCI: JACC State-of-the-Art Review. J Am Coll Cardiol. 2023;81:590-605. Vulnerable plaque with large lipid content or thin caps raises post-procedural MI, distal embolization, and no-reflow; stents should span from the most normal distal to most normal proximal segment. jacc.org/doi/10.1016/j.jacc.2022.11.045

5. Plaque morphology and periprocedural MI after PCI. OCT cap thickness and lipid burden predict periprocedural infarction, presumably via distal embolization. pmc.ncbi.nlm.nih.gov/articles/PMC5441347

6. Chronic Total Occlusion, histopathology overview. Recanalized channels within organized thrombus enable guidewire crossing, which should be followed by thrombus removal before plaque modification and stenting. sciencedirect.com (Chronic Total Occlusion topic overview)

7. Riley RF, et al. Long-term outcomes of intravascular lithotripsy-facilitated stenting (pooled Disrupt CAD III and IV). J Soc Cardiovasc Angiogr Interv. 2023. Stents in inadequately prepared calcific lesions underexpand or malappose, raising stent thrombosis, restenosis, and target vessel failure. jscai.org

8. Lesion-specific coronary calcium assessment to predict stent underexpansion. Intravascular imaging-based calcium scoring (OCT angle, thickness, length; IVUS superficial calcium criteria) directs lesion preparation, including atherectomy or lithotripsy. pmc.ncbi.nlm.nih.gov/articles/PMC11832659

9. Sato Y, Finn AV, et al. Calcified Nodule in PCI: Therapeutic Challenges. JACC Cardiovasc Interv. 2024. OCT/IVUS distinguish eruptive from non-eruptive nodules; CLIMA registry showed roughly 20% cardiac death or target-lesion MI for eruptive nodules versus 2.7% non-eruptive. jacc.org/doi/10.1016/j.jcin.2024.03.032

10. NIRS lipid-core burden and microvascular obstruction after PCI. EuroIntervention. Lesions with maxLCBI(4mm) at higher thresholds showed about a 50% periprocedural MI risk versus roughly 4% for low-lipid lesions. eurointervention.pcronline.com

11. Jia H, et al. Effective anti-thrombotic therapy without stenting: OCT-based management in plaque erosion (EROSION study). Eur Heart J. 2017;38:792-800. Selected ACS patients with plaque erosion were stabilized on antithrombotic therapy without stent implantation. pubmed.ncbi.nlm.nih.gov/27578806

12. EROSION III randomized trial. OCT guidance reduced stent implantation in STEMI without plaque rupture (about 43.8% vs 58.8% with angiographic guidance). tctmd.com (EROSION III)

13. Wu EB, Brilakis ES, et al. Global Chronic Total Occlusion Crossing Algorithm: JACC State-of-the-Art Review. J Am Coll Cardiol. 2021. Confirming true-lumen position is central; ambiguous proximal caps are routed to IVUS or move-the-cap strategies. jacc.org/doi/10.1016/j.jacc.2021.05.055

14. Carlino M, et al. CTO recanalization by intraocclusion injection of contrast: the microchannel technique. Catheter Cardiovasc Interv. 2008. Most CTOs contain intraluminal microchannels of roughly 100 to 500 microns that can serve as a guidewire crossing pathway. onlinelibrary.wiley.com/doi/10.1002/ccd.21396

15. Sakakura K, et al. Fundamental Wire Technique and Current Standard Strategy of PCI for CTO With Histopathological Insights. JACC Cardiovasc Interv. 2011. Older occlusions show dense calcium without microchannels, whereas younger lesions contain microchannels in organized thrombus. jacc.org/doi/10.1016/j.jcin.2011.06.011

16. Spontaneous coronary artery dissection: clinically oriented review. npj Cardiovasc Health. 2024. Intracoronary imaging confirms wire position (true vs false lumen), localizes the intimal breach, and guides stent sizing; most SCAD is managed conservatively. nature.com/articles/s44325-024-00004-y

17. Intravascular imaging of in-stent restenosis and calcified neointima; IVL and OCT-guided management of stent underexpansion. Restenosis mechanism (hyperplasia, neoatherosclerosis, calcified neointima, underexpansion) guides treatment selection. pmc.ncbi.nlm.nih.gov/articles/PMC8351610

18. A Practical Approach to Assessing Stent Results with IVUS or OCT; SCAI Expert Consensus on In-Stent Restenosis and Stent Thrombosis. Minimal stent area is the strongest predictor of stent thrombosis and restenosis; optimized targets are roughly MSA > 4.5 mm2 (OCT) or > 5.0 mm2 (IVUS), or relative expansion > 80%. journal.houstonmethodist.org/articles/10.14797/mdcj-14-1-32; jscai.org

19. Ali ZA, Landmesser U, et al. OCT predictors of clinical outcomes after stent implantation: the ILUMIEN IV trial. Eur Heart J. 2024;45:4630. OCT guidance achieved larger minimal stent area; optimized stent dimensions were associated with freedom from stent-related adverse events. academic.oup.com/eurheartj/article/45/43/4630/7743289

20. SCAI Expert Consensus Statement on Management of In-Stent Restenosis and Stent Thrombosis. J Soc Cardiovasc Angiogr Interv. 2023. OCT and IVUS reveal underexpansion, malapposition, uncovered struts, stent fracture, and neoatherosclerosis as distinct, treatment-defining mechanisms of stent failure. jscai.org/article/S2772-9303(23)00406-4/fulltext

21. Stone GW, Maehara A, Lansky AJ, et al. A Prospective Natural-History Study of Coronary Atherosclerosis (PROSPECT). N Engl J Med. 2011;364:226-235. Non-culprit lesions with thin-cap fibroatheroma, large plaque burden, and small lumen area predicted future events independent of stenosis severity. pubmed (PROSPECT)

22. Erlinge D, et al. Identification of vulnerable plaques and patients by intracoronary NIRS and ultrasound (PROSPECT II). Lancet. 2021;397:985-995; Kedhi E, et al. Thin-cap fibroatheroma predicts events in diabetic patients with normal FFR (COMBINE OCT-FFR). Eur Heart J. 2021;42:4671. Intracoronary imaging identifies high-risk plaques and patients prone to future events. thelancet.com

23. Park SJ, Ahn JM, Kang DY, et al. Preventive PCI versus optimal medical therapy alone for vulnerable atherosclerotic coronary plaques (PREVENT). Lancet. 2024;403:1753-1765. First large RCT: preventive PCI of non-flow-limiting vulnerable plaque reduced the 2-year primary outcome (0.4% vs 3.4%). Results are debated given the open-label design and low absolute event rates. thelancet.com (PREVENT, and accompanying correspondence)