There is a patient population in interventional cardiology that we discuss less than we should.

They have multivessel coronary artery disease. They need revascularization. And their kidneys cannot tolerate the contrast that makes revascularization possible.

Patients with an estimated GFR below 30 mL/min face a contrast-induced acute kidney injury (CI-AKI) rate exceeding 26% when undergoing PCI — with more than 4% progressing to in-hospital dialysis. Renal insufficiency is the second most common reason patients with multivessel disease are turned down for surgery entirely. When these patients do reach the cath lab, the relationship between contrast volume and CI-AKI is linear and unforgiving: a contrast-volume-to-creatinine-clearance ratio above 2 is an independent predictor of injury. Below 1 is the goal. For a patient with eGFR of 18, that means a maximum of 18 mL of contrast to guide a complete coronary revascularization.

This is a solvable problem. But solving it requires reimagining how we guide these procedures.

Why CI-AKI Is More Consequential Than a Lab Value

CI-AKI is often perceived as a transient bump in creatinine — clinically important, but manageable. The literature tells a more serious story.

Published data show that CI-AKI operates at three distinct levels of harm. Acutely, it triggers dialysis in more than 4% of advanced CKD patients undergoing PCI — a rate that carries significant in-hospital mortality. In the short term, 18.6% of patients who develop CI-AKI suffer persistent, irreversible renal damage at three months — a meaningful proportion who never recover to their pre-procedure baseline. At five years, even patients who experienced only transient CI-AKI show significantly reduced survival compared to those who had none.

To capture this multifaceted burden, the field has adopted the MARCE composite endpoint — Major Adverse Renal and Cardiovascular Events — which includes renal failure requiring dialysis, myocardial infarction, stroke, heart failure, renal or cardiac hospitalization, and death. MARCE is the relevant outcome measure for understanding the true downstream cost of CI-AKI in complex PCI patients, and it is increasingly used as the primary endpoint in trial design.

The economic dimension compounds the clinical one. Each CI-AKI event extends hospital stay, increases resource utilization, and in dialysis-requiring cases generates costs that dwarf the procedure itself. For hospital systems managing high volumes of CKD patients in the cath lab, the incentive to adopt contrast-minimizing protocols is not only clinical — it is financial.

CI-AKI in advanced CKD is not a manageable side effect. It is a potentially irreversible complication with five-year mortality implications — and its prevention is both a clinical imperative and an economic one.

Prevention Starts Before the Catheter Is Inserted

It is important to acknowledge that procedural contrast management does not exist in isolation. The published protocols that define best practice in this space include a robust pre-procedural layer: intravenous hydration tailored to left ventricular filling pressure or bioimpedance, pre-procedural rosuvastatin (which reduces CI-AKI risk by up to 62% in randomized trials in high-risk populations), cessation of nephrotoxic medications at least 48 hours before contrast exposure, and in the highest-risk cases, matched hydration with the RenalGuard system — which has demonstrated 53–78% reductions in CI-AKI rates compared to standard hydration protocols.

These measures are complementary to, not competitive with, procedural contrast minimization. The best outcomes come from stacking them. What makes the procedural layer distinctive is that it is the only one with no ceiling — pre-procedural hydration can reduce risk but cannot eliminate it if contrast volume remains high. Ultra-low contrast technique can bring the procedural contrast burden to near zero, which no pre-procedural measure can achieve.

What the State of the Art Actually Looks Like

Over the past decade, a small group of interventionalists — led by pioneers including Dr. Lorenzo Azzalini at San Raffaele Scientific Institute in Milan — have developed and published ultra-low contrast PCI (ULC-PCI) protocols that have redefined what is technically possible in the most fragile patients.

The turning point in establishing the clinical case came from the MOZART randomized controlled trial (Mariani et al., JACC Cardiovasc Interv 2014) — the first RCT to demonstrate that IVUS-guided PCI with rigorous contrast-sparing technique could reduce total contrast volume from 64.5 mL to 20 mL compared to angiography-guided PCI. That 69% reduction, achieved in a controlled trial setting, established the proof of concept that intravascular imaging could substitute meaningfully for contrast guidance.

Building on MOZART, Azzalini and colleagues constructed a comprehensive ULC-PCI protocol built on six pillars:

• Intravascular imaging as the primary guidance modality — IVUS for large vessels, CTOs, and aorto-ostial disease; dextran-based OCT for bifurcations, heavily calcified lesions, and cases requiring multiple imaging runs

• Diluted contrast (50% with normal saline) reserved for critical decision points only — typically a single confirmatory injection at the end of the procedure

• Metallic roadmapping — side-branch wires advanced into key tributaries to provide indirect fluoroscopic topographic reference for device positioning

• Pre-specified contrast limits — a CV/eGFR target below 1, set before the case begins, communicated as a team commitment during the pre-procedural time-out

• Staged procedures — separating diagnostic angiogram from PCI by several days to allow contrast clearance and reduce cumulative renal exposure

• Hemodynamic support in the highest-risk cases — Impella deployment in patients with reduced ejection fraction undergoing complex or prolonged procedures, since transient hypotension is an independent CI-AKI trigger that compounds contrast nephrotoxicity

Applied to a cohort with eGFR consistently below 30 mL/min — including B2/C lesions in 100% of cases, CTOs, left main bifurcations, and cases requiring rotational atherectomy — technical success was 100% and CI-AKI rate was 0%. Median contrast: 8.8 mL. For a distal LAD CTO with Impella support and rotational atherectomy, the total contrast was 14 mL.

These are not theoretical results. They are published, peer-reviewed, and reproducible — at least in highly expert hands, in a single center, performed exclusively by one experienced operator. That last clause is important, and we return to it.

Zero-Contrast vs. Ultra-Low Contrast: An Important Distinction

The literature distinguishes between zero-contrast PCI and ultra-low contrast PCI, and the distinction matters clinically.

Zero-contrast PCI — using IVUS guidance with coronary physiology testing and no contrast administration — has been demonstrated in small series with excellent results in carefully selected patients. But complete elimination of contrast introduces a specific set of procedural risks that ULC-PCI deliberately preserves the ability to address:

• Perforation — a zero-contrast approach cannot detect distal vessel perforation in real time; peri-procedural echocardiography can identify pericardial effusion after the fact but does not rule out delayed effusions from small perforations during the procedure

• Dissection in unwired side branches — branches that are not roadmapped with guidewires may be dissected without any fluoroscopic indication

• No-reflow and distal embolization — clinical or electrocardiographic signs may indicate ischemia, but bailout angiography requires contrast

• Incomplete complication assessment — a small contrast injection at the end of an otherwise contrast-minimized procedure provides an enormous amount of diagnostic information about the treated segment and adjacent anatomy simultaneously

The Azzalini group's position — and the one supported by the available evidence — is that ULC-PCI, with a pre-specified contrast budget and a single end-of-case confirmatory injection, represents a better risk-benefit balance than absolute zero contrast for most complex cases. The goal is not zero; it is the minimum necessary to maintain clinical safety. For a patient with eGFR of 20, achieving a CV/eGFR ratio below 1 means staying under 20 mL — well within a range that is both protective and clinically defensible.

The Hidden Cost: Cognitive Load and the Operator Dependency Problem

The state of the art works. The state of the art is not widely practiced. Understanding why requires an honest assessment of what ULC-PCI demands.

In standard PCI, contrast is the integrating medium. A brief injection answers multiple questions simultaneously: wire position relative to the lesion, device alignment, stent expansion, side branch patency, distal flow, presence of dissection or perforation. It does this in the same anatomical plane where the operator is working, with the full vessel segment visible at once, in real time.

In ULC-PCI, none of that integration is available. The operator must mentally assemble a coherent three-dimensional picture of a vessel from three separate, discontinuous, and spatially misaligned data streams:

• Fluoroscopy — showing wire and device position in a 2D projection, with no tissue information

• IVUS or OCT cross-sections — exquisite detail of a single vessel location at a time, requiring a separate catheter pass and pullback, mentally registered to the fluoroscopic image

• Metallic roadmap — indirect topographic reference from side-branch wire positions, with no information about lumen dimensions, plaque burden, or device interaction with the vessel wall

Each data stream is individually valuable. None provides the continuous, spatially integrated, lumen-level guidance that operators rely on when contrast is available. The mental work of synthesizing them — in real time, in a high-risk patient, through a calcified and tortuous vessel, with a contrast budget measured in single-digit milliliters — is cognitively exhausting and procedurally unforgiving.

The Azzalini series — the most comprehensive published ULC-PCI experience — explicitly notes that all procedures were performed exclusively by one experienced operator, and that the widespread applicability of the protocol could not be evaluated. That sentence is the clinical case for better tools in a single line.

The consequence is predictable. Operators bifurcate. Some don't attempt the procedure at all, leaving CKD patients with undertreated CAD. Others attempt it but reach for contrast when uncertainty mounts — when a wire position is ambiguous, when a stent edge looks suboptimal, when a side branch disappears from the roadmap. Both failure modes trace to the same root cause: the guidance operators need to act with confidence is not available continuously, in the plane where they are working.

There is also a procedural tradeoff that deserves honest acknowledgment: ULC-PCI takes longer.

Median fluoroscopy time in the Azzalini series was 39 minutes for ULC-PCI cases versus 21 minutes in conventional PCI — nearly double. Extended fluoroscopy means increased radiation exposure for patient and operator, longer procedure duration in a high-risk patient under sedation, and greater opportunity for hemodynamic instability. This is a real cost of the current approach, and it reinforces the argument for imaging technology that reduces — rather than compounds — procedural complexity.

The tool gap is the access gap.

What IVUS and OCT Cannot Do

IVUS and OCT are exceptional tools with well-established clinical benefit in complex PCI. The case for intravascular imaging guidance — independent of contrast considerations — is now supported by multiple randomized trials showing reductions in MACE, stent thrombosis, and repeat revascularization. Neither technology is going away, and both will remain foundational elements of the ULC-PCI protocol.

But in the specific context of ULC-PCI, both have structural limitations that the current approach works around rather than resolves:

IVUS limitations:

• Pullback-based — vessel segment information is available only during active catheter transit; there is no persistent real-time view

• Lower resolution — approximately 100–150 microns axial resolution versus 10–15 microns for OCT; limits stent apposition assessment, edge dissection detection, and calcium architecture characterization

• Does not image through blood — live-view mode requires slow flow or vessel preparation; not usable for real-time positional guidance

• Each imaging run adds fluoroscopy time and catheter exchanges — compounding the procedural duration problem already inherent in ULC-PCI

OCT limitations:

• Requires blood clearance for every acquisition — dextran-40 substitution is effective and safe below 100 mL, but each pullback consumes 14 mL of flush; complex cases with multiple imaging runs approach the safety boundary

• Pullback-based — same discontinuous guidance limitation as IVUS

• Limited penetration depth — 1–3 mm; insufficient for full-thickness vessel wall assessment in heavily calcified or fibrotic lesions

• Dextran carries its own procedural risks — anaphylaxis, coagulopathy, and rare nephrotoxicity; well within safety margins at standard volumes, but these risks are real and require monitoring

• Measurement correction required — dextran's different refractive properties from contrast require a correction coefficient for accurate dimensional measurements; adds a step that can introduce error

Neither modality provides what contrast provides: a rapid, panoramic, real-time view of the target segment and surrounding anatomy, simultaneously answering multiple clinical questions in the same plane where the operator is working. That gap is the procedural bottleneck — and it is the gap a next-generation intravascular imaging platform must close.

What the Next Generation of Intravascular Imaging Needs to Deliver

The procedural architecture Azzalini and colleagues built is the right architecture. It will remain the foundation of ULC-PCI for the foreseeable future. What the framework needs is a sensor capable of replacing contrast's integrating function — not replicating it perfectly, but providing continuous, lumen-level guidance that operators can act on in real time without stopping the procedure to acquire it.

Real-time continuous visualization. Not pullback-based. Not per-acquisition. A persistent view of lumen morphology and device position throughout wire crossing, balloon inflation, stent deployment, and post-dilation — without procedural interruption.

Blood penetration. The inability to image through blood is OCT's core constraint in real-time guidance applications. A modality that maintains useful imaging in a blood-filled lumen eliminates the flush requirement, the dextran volume accumulation, and the procedural pause that each acquisition currently demands.

Lesion and tissue characterization. Calcium depth and distribution, lipid-rich plaque, fibrous cap architecture — the information that guides plaque modification strategy. In ULC-PCI, operators routinely encounter fibrocalcified disease requiring rotational atherectomy or scoring balloon preparation; imaging that characterizes this in real time directly reduces the uncertainty that currently drives contrast use.

Stent deployment verification without contrast. Edge dissection, under-expansion, malapposition — the complications that currently force operators to reach for contrast at the end of an otherwise contrast-minimized case. If intravascular imaging can rule these out with confidence equivalent to a contrast injection, the case for near-zero contrast PCI becomes defensible across a much broader operator base.

Perforation surveillance. The most dangerous complication in ULC-PCI is the one you can't see in real time. A continuous intravascular view that detects vessel integrity compromise as it occurs — rather than inferring it from hemodynamic instability or post-procedure echocardiography — is a meaningful patient safety advance.

Multi-modal information in a single catheter pass. The cognitive burden of integrating IVUS, OCT, and fluoroscopic data streams is itself a source of procedural risk. Consolidating morphological, compositional, and positional information into a single, continuously updated view reduces that burden and reduces the opportunity for integration errors.

Where SFE Fits: The VerAvanti Platform and Why Existing Solutions Fall Short

The interventional imaging market is not standing still. Major players — including Abbott (OCT), Boston Scientific (IVUS), and Philips following its acquisition of Spectrawave — are actively developing next-generation intravascular imaging platforms. These investments reflect the same clinical recognition that motivates ULC-PCI: that intravascular imaging needs to do more.

But the fundamental limitations of existing approaches are architectural, not incremental. IVUS is acoustic — it cannot achieve OCT-level resolution regardless of processing improvements. OCT is interferometric — it requires blood clearance for every acquisition, a constraint that cannot be resolved without changing the underlying physics. The next generation of IVUS and OCT will be better versions of what they already are. They will not be continuous. They will not penetrate blood. They will not eliminate the pullback-based, discontinuous guidance model that defines the current state of the art.

At VerAvanti, we are developing the Scanning Fiber Endoscope (SFE) platform — a single-fiber intravascular imaging system built on direct optical imaging rather than acoustic or interferometric reconstruction. The SFE uses a single scanning optical fiber to illuminate and collect reflected light from the vessel wall, generating a high-resolution, real-time display that is continuous by design — not a sequence of discrete cross-sections assembled after the fact.

The clinical value proposition for ULC-PCI is direct and specific:

• Real-time procedural guidance — continuous visualization of wire position, lumen geometry, and side branch anatomy throughout the procedure

• Stent deployment confirmation without contrast — direct visual assessment of strut apposition, edge geometry, and expansion

• Calcium and tissue characterization — morphological information to guide plaque modification strategy in fibrocalcified disease

• Bifurcation visualization — direct imaging of side branch orifice geometry and carina position; one of the highest contrast-consumption moments in complex PCI

• Complication surveillance — real-time assessment for dissection, perforation, or no-reflow as the procedure unfolds

• Reduced procedural duration — continuous guidance reduces the need for iterative imaging runs and catheter exchanges, addressing the fluoroscopy time disadvantage of current ULC-PCI protocols

SFE is not yet FDA-cleared. But the clinical specification for what it needs to do has been written with precision by the interventionalists who built the current standard of care. We are building toward that specification.

Beyond Cardiology: A Platform With Multi-Specialty Reach

The clinical case developed in this article is specific to coronary intervention in CKD patients. But the SFE platform's value proposition extends substantially beyond that application — and understanding the full platform opportunity matters for evaluating the investment thesis.

The same continuous, real-time, blood-penetrating imaging capability that addresses contrast management in ultra-low contrast PCI has direct clinical relevance across multiple procedural specialties:

Chronic Total Occlusion (CTO) PCI. CTO crossing is the highest-risk, highest-contrast, highest-complexity subset of coronary intervention. The critical variable in CTO crossing is wire position relative to the true lumen versus the subintimal space — information that current imaging provides only intermittently, and that operators currently infer from fluoroscopic and IVUS cues. Continuous real-time lumen visualization during CTO crossing would address the most consequential guidance gap in complex interventional cardiology.

Interventional Pulmonology. Peripheral airway imaging and bronchoscopic intervention face analogous guidance challenges — navigating to small, branching target anatomy without a contrast-based roadmap. The SFE platform's fiber architecture is adaptable to the airway lumen, creating a potential application in bronchoscopic biopsy guidance and therapeutic airway intervention. VerAvanti has engaged four European Interventional Pulmonology Key Opinion Leaders around this application.

Urology — Upper Tract Urothelial Carcinoma (UTUC). Ureteroscopic visualization of the upper urinary tract is currently limited by the resolution and field of view of conventional ureteroscopes. SFE's fiber architecture offers potential for high-resolution imaging in the confined geometry of the ureter and renal collecting system, with application to UTUC surveillance and treatment guidance.

Neurovascular Intervention. Cerebrovascular and endovascular neurosurgical procedures operate under similar contrast constraints to coronary intervention in patients with renal compromise, with the added risk that contrast neurotoxicity is a documented complication in certain patient subgroups. Real-time intravascular visualization in the cerebrovascular territory represents a longer-term but strategically significant application.

The multi-specialty architecture of the SFE platform means that FDA clearance in the coronary indication — the primary regulatory pathway — creates a foundation for sequential expansion into adjacent high-value procedural markets. Each expansion is a new revenue stream, a new clinical KOL network, and a new layer of competitive differentiation.

The Market Opportunity: Sizing the Problem

For investors evaluating this space, the addressable population is concrete. Published registry data from a high-volume complex PCI center show that approximately 1.5% of all PCI patients have eGFR ≤30 mL/min and are not on chronic dialysis — the population directly addressable by ULC-PCI protocols. Applied to U.S. PCI volume of approximately 600,000 procedures per year, that represents roughly 9,000 patients annually in the highest-risk tier, with a substantially larger population in the eGFR 30–45 range who benefit meaningfully from contrast reduction strategies.

The downstream cost of CI-AKI at current rates provides an equally concrete economic frame. More than 4% of high-risk PCI patients who develop CI-AKI require in-hospital dialysis. Each dialysis event carries direct costs well in excess of the procedure itself, extended ICU stay, and a high probability of long-term renal replacement therapy. Hospital systems bearing these costs have a direct financial incentive to adopt technologies that reduce CI-AKI rates — independent of the clinical mandate.

The intravascular imaging market is already large and growing. Global IVUS and OCT revenues exceed $1 billion annually and are expanding as the clinical evidence for imaging-guided PCI strengthens. A platform that extends imaging capability — enabling procedures that are currently not attempted, and improving outcomes in procedures that are — addresses a market that is both established and actively expanding.

The Patients Who Deserve Better

The patients who need ultra-low contrast PCI are among the most complex and highest-risk in interventional cardiology. Median age in published series is 76 years. Three-quarters are men. More than half have diabetes and prior myocardial infarction. The majority have reduced ejection fraction. Their coronary anatomy is B2/C in nearly every case.

They are the patients most likely to be turned down, most likely to suffer CI-AKI when intervened on conventionally, and most likely to have their coronary disease undertreated because the tools available to manage it safely are not in wide enough hands.

The evidence base for ULC-PCI is compelling. The techniques work. The outcomes, in experienced centers with highly specialized operators, are excellent. What the field needs now is not more proof that this can be done by the best operators under ideal conditions. It needs imaging technology that makes it executable — safely, confidently, reproducibly — across the broader population of interventionalists and institutions that care for these patients every day.

That is the standard we are building toward. These patients have waited long enough.

Acknowledgment: The clinical framework described in this article draws on published work by Dr. Lorenzo Azzalini and colleagues (J Invasive Cardiol 2019; EuroIntervention 2018; Can J Cardiol 2018), the landmark MOZART randomized controlled trial (Mariani et al., JACC Cardiovasc Interv 2014), and the CI-AKI state-of-the-art review (Almendarez et al., JACC Cardiovasc Interv 2019). The author is grateful for this foundational work, which continues to define the clinical and scientific standard in this field.

Juan Vegarra is Chief Marketing Officer at VerAvanti Corporation, a Seattle-based medical device company developing the Scanning Fiber Endoscope (SFE) platform for intravascular and multi-specialty imaging. VerAvanti is targeting FDA 510(k) submission in 2026. Nothing in this article should be construed as a claim of cleared or approved device performance.