Subintimal excimer laser coronary atherectomy (S-ELCA) as a bail-out for device-uncrossable chronic total occlusion: case report

Abstract

Background

Chronic total occlusion (CTO) that cannot be crossed with balloons or microcatheters despite successful guidewire passage represent one of the most challenging scenarios in percutaneous coronary intervention (PCI). Excimer laser coronary angioplasty (ELCA) is an established adjunct for device-uncrossable lesions; however, the safety of its application within the subintimal space remains limited.

Case summary

A 67-year-old male with a complex cardiac history, including prior recurrent interventions and coronary artery bypass grafting, was referred for staged PCI of a right coronary artery CTO because of refractory angina (Canadian Cardiovascular Society class III). Following successful antegrade subintimal wire tracking and re-entry using a Stingray balloon, multiple ultra-low-profile balloons and dedicated microcatheters failed to traverse the subintimal-to-true-lumen transition. A 0.9-mm ELCA catheter at 80 mJ/mm² and 80 Hz was used in the subintimal space without saline flush, successfully creating a traversable channel. Complete revascularization was achieved using six overlapping drug-eluting stents, optimized with intravascular ultrasound guidance. At two-year follow-up, repeat intravascular ultrasound demonstrated vascular healing at the subintimal-re-entry interface.

Discussion

This case demonstrates the potential safety and feasibility of subintimal ELCA (SELCA) as a bail-out for device-uncrossable lesions during antegrade dissection re-entry of CTO-PCI, with the first reported evidence of vascular healing at the subintimal laser site at two-year follow-up.

Learning points.

• In device-uncrossable CTO-PCI, subintimal ELCA without saline flush is a feasible bail-out strategy when all conventional crossing devices have failed.

• Intravascular ultrasound at two-year follow-up showed vascular healing at the subintimal re-entry interface, supporting the long-term safety of subintimal ELCA.

Introduction

Chronic total occlusion percutaneous coronary intervention (CTO-PCI) has undergone remarkable technical evolution, with contemporary success rates of 85%–90% by experienced operators. Despite these advances, device-uncrossable lesions remain challenging in approximately 9% of CTO cases.¹ A structured escalation strategy is mandated when conventional devices fail, including support optimization, low-profile balloons, specialized microcatheters, atherectomy-based approaches, and subintimal techniques.² Although excimer laser coronary angioplasty (ELCA) has traditionally been used to modify a resistant proximal cap or debulk an intraluminal uncrossable segment, herein we report a successful technique of subintimal ELCA (SELCA) as a bail-out for a device-uncrossable lesion at the subintimal-to-true-lumen interface during antegrade dissection and re-entry (ADR) of a right coronary artery (RCA) CTO-PCI.

Summary figure

Case presentation

A 67-year-old male was referred for staged PCI of an RCA CTO with worsening exertional angina (Canadian Cardiovascular Society class III) refractory to maximally tolerated antianginal therapy. He had an extensive cardiac history, including prior PCI to the left circumflex artery (LCX) (1997, 2002) and coronary artery bypass grafting (2014) with left internal mammary artery (LIMA) to the left anterior descending (LAD) artery and saphenous vein graft (SVG) to the obtuse marginal (OM) branch—the RCA was not grafted. Subsequently, he had PCI to the SVG-OM and native LCX (2017, 2021). Type 2 diabetes mellitus was managed with metformin and empagliflozin.

Stress perfusion cardiac magnetic resonance imaging (cMRI) demonstrated normal left ventricular function (ejection fraction 60%) and an inducible perfusion defect of the mid and basal inferoseptal and mid-inferior segments, consistent with myocardial ischaemia in the ungrafted RCA territory, and no late gadolinium enhancement to indicate established infarction, confirming viable myocardium in this territory. Diagnostic coronary angiography confirmed a mid-RCA CTO with a blunt proximal cap, superficial calcification, and occlusion length >20 mm (Japanese-CTO score of 3) (Figure 1). Retrograde filling from LAD septal collaterals was present (Rentrop Grade 2, Werner class 2).

Figure 1.

Coronary angiogram of the right coronary artery showing a chronic total occlusion (CTO) of the mid-RCA segment with blunt proximal cap, superficial calcification, and long occlusion length >20 mm (J-CTO score 3).

Bilateral femoral access was obtained with seven French (right) and eight French (left) sheaths. Radial access was not pursued due to bilateral poor radial pulses after repeated prior transradial procedures. In addition, the eight French sheath was needed to support IVUS-guided re-entry with microcatheter placement, a sheath calibre that can be reliably placed only through femoral access. An eight French JR4 guide catheter was placed in the RCA with a guide extension and was subsequently exchanged for an 8 French AL0.75 for additional support. Contralateral injection was performed via a seven French Voda Left guide catheter. Antegrade Dissection Re-entry (ADR) approach was selected given heavy calcification. After initial wire advancement with Sion Blue and Corsair microcatheter, a Hornet 14 wire punctured the calcified proximal cap. An ASAHI Gladius MG14 wire was knuckled into the subintimal space and advanced to the posterior descending artery (Figure 2). After pre-dilation with 1.5-mm and 2.0-mm balloons, a Stingray LP balloon was deployed, and the wire was advanced using the ‘stick and drive’ technique.

Figure 2.

Fluoroscopy of the antegrade dissection re-entry (ADR) approach, during which an ASAHI Gladius MG14 wire (white arrow) was knuckled into the subintimal space and advanced to the posterior descending artery (PDA), with support of a microcatheter (yellow arrow).

Despite confirmed distal true lumen wire position by contralateral injection, all subsequent attempts at advancing equipment from the subintimal space into the true lumen were unsuccessful. Multiple ultra-low-profile balloons (Emerge 1.2 mm, Alveo HP 1.0 mm, Ryurei 1.0 mm) were attempted, followed by 135-cm microcatheters (Turnpike Spiral, Mamba Flex), none of which crossed the subintimal-to-true-lumen transition. The case now represented a device-uncrossable scenario with wire access to the true lumen, but all conventional crossing devices had been exhausted.

A 0.9 mm X80 ELCA catheter (Philips) was advanced to the point of subintimal entry. Energy settings of 80 mJ/mm² fluence at 80 Hz were selected, and the catheter was slowly advanced through the subintimal dissection plane while lasing (Figure 3A, B) (see Supplementary material online, Video S1). Critically, neither saline nor contrast flushing was performed during laser activation. The laser successfully ablated the dense fibrous and calcified extra-plaque tissue, creating a traversable channel into the distal true lumen.

Figure 3.

Fluoroscopic frames showing subintimal ELCA (SELCA) technique. A 0.9 mm ELCA catheter (white arrow) was slowly advanced through the subintimal dissection plane at maximum energy settings (80 mJ/mm², 80 Hz) without saline flush, creating a traversable channel from the subintimal space (A) into the distal true lumen (B).

Sequential pre-dilation was performed with 1.5, 2.5, and 3.0 mm non-compliant balloons. Six overlapping drug-eluting stents (DES) were deployed from the PDA to the coronary ostium (2.5–3.5 mm diameters). Intravascular ultrasound identified mid-vessel malapposition (Figure 4A), subintimal catheter placement at the subtintimal-true lumen transition (Figure 4B), and proximal stent underexpansion (Figure 4C) (see Supplementary material online, Video S2). This was treated by post-dilatation using a 4.0-mm non-compliant balloon. Final coronary angiography demonstrated TIMI III flow with no complications (Figure 4D) (see Supplementary material online, Video S3). The patient was discharged two days later on dual antiplatelet therapy.

Figure 4.

Post-stenting intravascular ultrasound (IVUS) from distal to proximal showed mid-vessel stent malapposition (A), then subintimal catheter placement at the subintimal–true lumen transition (B), and proximal stent underexpansion (C). This was treated by balloon post-dilatation using a 4.0-mm non-compliant balloon. Final coronary angiogram showed TIMI III flow of the RCA with no evidence of perforation, dissection, or significant residual stenosis (D).

During follow-up, the patient was reviewed in clinic every six months and remained free of angina, with a considerable improvement in his quality of life. Two years following the index procedure, he was readmitted with a non-ST-elevation myocardial infarction (NSTEMI). Coronary angiography revealed distal RCA occlusion beyond the prior CTO intervention site, attributable to focal stent underexpansion with in-stent restenosis (ISR) due to neoatherosclerosis (Figure 5A). This segment was treated with a cutting balloon, a new DES bridging a gap between two previously placed stents, and a drug-coated balloon to the ISR (Figure 5B). This achieved successful TIMI III flow (Figure 5C). Importantly, IVUS assessment of the prior subintimal dissection re-entry interface using subintimal ELCA demonstrated vascular healing with no evidence of ISR (Figure 5D) (see Supplementary material online, Video S4).

Figure 5.

Angiography demonstrated a new distal RCA occlusion just beyond the original CTO intervention site, caused by underexpansion of the existing stent with neoatherosclerotic in-stent restenosis (ISR) (A). The lesion was managed with cutting-balloon angioplasty, a new drug-eluting stent (DES) bridging a gap between two previously placed stents, and a drug-coated balloon across the ISR segment (B), restoring TIMI III flow (C). IVUS interrogation of the original subintimal re-entry point using the ELCA confirmed a well-healed vessel wall with no evidence of restenosis at that site (D).

Discussion

ELCA uses a pulsed 308 nm ultraviolet xenon-chloride laser delivered through flexible fibreoptic catheters to ablate tissue via photochemical, photothermal, and photokinetic mechanisms. The 0.9 mm catheter permits maximum energy delivery (80 mJ/mm², 80 Hz) and can be advanced over any standard 0.014-in. PCI guidewire without the requirement to exchange for dedicated wires.^3,4

For intraluminal use in uncrossable CTO lesions, published ELCA series report procedural success rates between 81.8% and 90%.^5,6 To our knowledge, the use of ELCA within the subintimal space was first published by Ribeiro et al.⁷ in a case of an uncrossable long CTO. Frizzell et al.⁸ subsequently described this approach as the ‘Extra-plaque Laser to Assist in Crossing Occlusion’ (EL TACO) technique. Our case shares key technical features with both reports while adding IVUS assessment at two-year follow-up. To our knowledge, neither prior report included follow-up imaging, making this the first demonstrating evidence of vascular healing at the subintimal laser site.

The decision to avoid saline flush during subintimal ELCA is important. In intraluminal ELCA, saline displaces blood at the laser–tissue interface, enhancing the photomechanical ablative effect. However, in the subintimal space, saline injection may precipitate hydraulic dissection and extension into major side branches.⁸

Safety considerations require careful attention. The NCDR/CATH PCI analysis of 19 688 ELCA-treated lesions demonstrated that CTO use was associated with approximately twice the complication rate compared with other indications; these were mitigated by continuous saline infusion during lasing.⁹ In the subintimal space, the theoretical risk of perforation towards the adventitia is further elevated.

The current European Society of Cardiology guidelines recommend PCI of CTO lesions in patients with persistent symptoms despite optimal medical therapy when technically feasible (class IIa, level of evidence B), though they do not specifically address subintimal ELCA use, highlighting the need for further evidence in this area.¹⁰

This case demonstrates subintimal ELCA as a viable bail-out strategy when all conventional devices fail to cross a device-uncrossable CTO at the subintimal-to-true-lumen interface. Key technical principles include deliberate omission of saline flush, confirmed distal true lumen wire position, and IVUS-guided stent optimization.

Lead author biography

Dr Ahmed Elsherif graduated from Suez Canal University, Egypt, in 2015. He completed his cardiology residency and obtained a Master’s Degree in Cardiovascular Science in 2020, and is currently an Interventional Cardiology Registrar in the West Midlands Deanery, United Kingdom. He is passionate about integrating advanced clinical training with evidence-based practice and research to enhance patient outcomes in coronary intervention. His research interests include coronary artery disease and imaging-guided percutaneous coronary intervention.

Supplementary material

Supplementary material is available at European Heart Journal – Case Reports online.

Author contributions

Ahmed Elsherif (Writing—original draft [lead]), Ameenathul Fawzy (Writing—review & editing [equal]), Sophia Khattak (Writing—review & editing [supporting]), Farhan Shahid (Supervision [lead]), and Sohail Q. Khan (Supervision [lead])

Consent

Informed consent for publication of this case report, including clinical details, images, and videos, was obtained from the patient using the European Heart Journal—Case Reports consent form, in accordance with COPE best practice guidelines.

Funding

No funding was required for this work.

Data availability

All data underlying this article are available within the article and its supplementary materials.