Procedure failure of chronic total occlusion percutaneous coronary intervention in an algorithm driven contemporary Asia‐Pacific Chronic Total Occlusion Club (APCTO Club) multicenter registry

2D array imaging system for mechanically-steered, forward-viewing ultrasound guidewire

Approximately 4 million people with peripheral artery disease (PAD) present with critical limb ischemia each year, requiring urgent revascularization to avoid loss of limb. Minimally-invasive (i.e. endovascular) revascularization is preferable due to increased recovery time and increased risk of complications associated with open surgery. However, 40% of people with PAD also have chronic total occlusions (CTOs), resulting in > 20% of revascularization procedures failing when CTOs are present. A steerable robotic guidewire with integrated forward-viewing imaging capabilities would allow the guidewire to navigate through tortuous vasculature and facilitate crossing CTOs in revascularization procedures that currently fail due to inability to route the guidewire. The robotic steering capabilities of the guidewire can be leveraged for 3D synthetic aperture imaging with a simplified, low element count, forward-viewing 2D array on the tip of the mechanically-steered guidewire. Images can then be formed using a hybrid beamforming approach, with focal delays calculated for each element on the tip of the guidewire and for each physical location to which the robotically-steered guidewire is steered. Unlike synthetic aperture imaging with a steerable guidewire having only a single element transducer, an array with even a small number of elements can allow estimation of blood flow and physiological motion in vivo. A miniature, low element count 2D array transducer with 9 total elements (3 × 3) having total dimensions of 1.5 mm × 1.5 mm was designed to operate at 17 MHz. A proof-of-concept 2D array transducer was fabricated and characterized acoustically. The developed array was then used to image a wire target, a peripheral stent, and an ex vivo porcine iliac artery. Images were formed using the described synthetic aperture beamforming strategy. Acoustic characterization showed a mean resonance frequency of 17.6 MHz and a -6 dB bandwidth of 35%. Lateral and axial resolution were 0.271 mm and 0.122 mm, respectively, and an increase in SNR of 4.8 dB was observed for the 2D array relative to the single element case. The first 2D array imaging system utilizing both mechanical and electronic steering for guidewire-based imaging was developed and demonstrated. A 2D array imaging system operating on the tip of the mechanically-steered guidewire provides improved frame rate and increases field of view relative to a single element transducer. Finally, 2D array and single element imaging were compared for introduced motion errors, with the 2D array providing a 46.1% increase in SNR, and 58.5% and 17.3% improvement in lateral and axial resolution, respectively, relative to single element guidewire imaging.

Chronic Total Occlusions: A State-of-the-Art Review

The percutaneous management of chronic total occlusions (CTO) is a well-established sub-specialty of Interventional Cardiology, requiring specialist equipment, training, and techniques. The heterogeneity of approaches in CTO has led to the generation of multiple algorithms to guide operators in their management. The evidence base for management of CTOs has suffered from inconsistent descriptive and quantitative terminology in defining the nature of lesions and techniques utilised, as well as seemingly contradictory data about improvement in ventricular function, symptoms of angina, and mortality from large-scale registries and randomised controlled trials. Through this review, we explore the history of CTO management and its supporting evidence in detail, with an outline of limitations of CTO-percutaneous coronary intervention and a look at the future of this growing field within cardiology.

Wire-based antegrade dissection re-entry technique for coronary chronic total occlusions percutaneous revascularization: Experience from the ERCTO Registry

BACKGROUND

The recent development and widespread adoption of antegrade dissection re-entry (ADR) techniques have been underlined as one of the antegrade strategies in all worldwide CTO consensus documents. However, historical wire-based ADR experience has suffered from disappointing long-term outcomes.

AIMS

Compare technical success, procedural success, and long-term outcome of patients who underwent wire-based ADR technique versus antegrade wiring (AW).

METHODS

One thousand seven hundred and ten patients, from the prospective European Registry of Chronic Total Occlusions (ERCTO), underwent 1806 CTO procedures between January 2018 and December 2021, at 13 high-volume ADR centers. Among all 1806 lesions attempted by the antegrade approach, 72% were approached with AW techniques and 28% with wire-based ADR techniques.

RESULTS

Technical and procedural success rates were lower in wire-based ADR than in AW (90.3% vs. 96.4%, p < 0.001; 87.7% vs. 95.4%, p < 0.001, respectively); however, wire-based ADR was used successfully more often in complex lesions as compared to AW (p = 0.017). Wire-based ADR was used in most cases (85%) after failure of AW or retrograde procedures. At a mean clinical follow-up of 21 ± 15 months, major adverse cardiac and cerebrovascular events (MACCEs) did not differ between AW and wire-based ADR (12% vs. 15.1%, p = 0.106); both AW and wire-based ADR procedures were associated with significant symptom improvements.

CONCLUSIONS

As compared to AW, wire-based ADR is a reliable and effective strategy successfully used in more complex lesions and often after the failure of other techniques. At long-term follow-up, patient's MACCEs and symptoms improvement were similar in both antegrade techniques.

Operator experience and clinical outcomes of percutaneous coronary intervention for chronic total occlusion: insights from a pooled analysis of the Japanese CTO PCI Expert Registry and the Retrograde Summit General Registry

There have not been enough studies to examine the association between difference in operator experience and technical success rate in contemporary percutaneous coronary intervention for chronic total occlusion (CTO-PCI). The present study sought to provide insights into the impact of operator experience on clinical outcomes of CTO-PCI through a comparison of two largest Japanese CTO-PCI registries consisting of operators with different CTO-PCI experience. After combining clinical data from the Japanese CTO-PCI Expert Registry (ER) 2014-2016 (N = 4316) including CTO-PCI performed by highly experienced operators and the Retrograde Summit General Registry (RSGR) 2014-2016 (N = 2230) including CTO-PCI performed by less experienced operators, a pooled analysis was performed to compare clinical outcomes of CTO-PCI in 2 registries. The overall technical success rate and the incidence of in-hospital major adverse events were comparable between ER and RSGR (90.1% vs 88.9%, p = 0.133, 1.7% vs 1.5%, p = 0.606, respectively). Technical success rate in ER was significantly higher among the patients treated with primary antegrade approach (91.8% vs 89.5%, p = 0.009), whereas there was no significant difference among the patients treated with the primary retrograde approach (85.7% vs 85.3%, p = 0.857). Multivariate analysis suggested ER operator could not be an independent predictor for technical success. CTO-PCI performed by less experienced but appropriately trained operators could achieve similarly high technical success rate with comparable safety compared with those performed by highly experienced specialists in contemporary Japanese context.

Contemporary Issues in Chronic Total Occlusion Percutaneous Coronary Intervention

Remarkable progress has been achieved in chronic total occlusion (CTO) percutaneous coronary intervention (PCI) in recent years, with refinement of the indications and technical aspects of the procedure, imaging, and complication management. Randomized controlled trials and rigorous prospective registries have provided high-quality data on the benefits and risks of CTO PCI. Global collaboration has led to an agreement on nomenclature, indications, endpoint definition, and principles of clinical trial design that have been distilled in global consensus documents such as the CTO Academic Research Consortium. Increased use of preprocedural coronary computed tomography angiography and intraprocedural intravascular imaging, as well as development of novel techniques and structured CTO crossing and complication management algorithms, allow a systematic, stepwise approach to this difficult lesion subset. This state-of-the-art review provides a comprehensive discussion about the most recent developments in the indications, preprocedural planning, technical aspects, complication management, and future directions of CTO PCI.

Outcomes of contemporary versus conventional reverse controlled and antegrade and retrograde subintimal tracking in chronic total occlusion revascularization

BACKGROUND

Chronic total occlusion (CTO) lesions remain technically challenging for percutaneous coronary intervention (PCI). The introduction of a retrograde approach has allowed marked improvement in the success rate of CTO recanalization. Reverse controlled anterograde and retrograde sub-intimal tracking (reverse CART) is the predominant retrograde wire crossing technique and can be broadly classified into three categories: (1) conventional (2) contemporary and (3) extended. The present study aimed to compare the safety and efficacy of conventional and contemporary reverse CART techniques.

METHODS

From March 2015 to May 2020, 303 patients achieving successful retrograde guidewire crossing with conventional or contemporary reverse CART during CTO PCI were included in the study. The patient characteristics, procedural outcomes and in-hospital and 1-year clinical events were compared between the conventional and contemporary groups.

RESULTS

The distributions of the baseline and angiographic characteristics were similar in both study arms, except the CTO lesions of the conventional group were more complex, as reflected by borderline significantly higher mean J-CTO scores (3.4 ± 0.7 vs. 3.3 ± 0.8; p = 0.059). Recanalization using contemporary reverse CART was associated with a short procedure time (189.8 ± 44.4 vs. 181.7 ± 37.3 min; p = 0.044) and decreased procedural complications, particularly target vessel perforation (3.6% vs. 0.6%; p = 0.063) and major side-branch occlusion (36.7% vs. 28.0%; p = 0.051). Technical and procedural success and the in-hospital and 1-year outcomes were not significantly different between the groups.

CONCLUSIONS

Contemporary reverse CART is associated with favorably high efficiency and low-complication rates and carries a comparable success rate and 1-year clinical outcomes as conventional reverse CART.

Overview of Contemporary Chronic Total Occlusion Percutaneous Coronary Intervention Techniques: A Narrative Systematic Review

BACKGROUND

Despite the abundance of coronary chronic total occlusions (CTO) percutaneous coronary intervention (PCI) studies, the literature is not easy to digest for both general PCI operators and CTO PCI specialists because of the many varied terms used for approaches and inconsistency in terminology. This inconsistency makes it challenging to understand the advantages and disadvantages of these different approaches and, most importantly, their downstream clinical outcomes. Accordingly, we conducted a systematic review of all published studies on CTO PCI to describe techniques and algorithms used in the last decade to provide an overview on the efficacy and safety of contemporary CTO PCI techniques.

METHODS

We performed a comprehensive search of the PubMed, EMBASE, and the Cochrane library databases for manuscripts about PCI of CTOs. We included studies published between the years 2005 and 2019. We categorized studies into those using a single approach (antegrade, retrograde) and those with a prespecified algorithm (ie, hybrid approach).

RESULTS

Fifty-five observational studies including 28,907 patients who underwent CTO were included in this review. CTO PCI generally carries low risk of major procedural complications, with angiographic success rates being higher in studies that used an algorithmic vs single technical approach.

CONCLUSIONS

This systematic review highlights the wide variation in definitions and practices in CTO PCI and calls for standardization in terminology and practice.

A case of right coronary artery chronic total occlusion with difficulty in retrograde system establishment

Advances in microcatheters (MCs) enables the establishment of retrograde systems for the treatment of chronic total occlusion (CTO). However, there are still cases in which establishing a retrograde system is difficult because the guidewire or MC cannot pass through due to calcification, stenosis, or tortuosity. We present a case of a 56-year-old man with angina. Coronary angiography revealed a CTO of the right coronary artery (RCA). Although we started an antegrade approach at first, the guidewire went to subintimal lumen. We switched to a retrograde approach. Although the guidewire passed through posterolateral (PL) channel, the MC could not pass due to a stenosis at the junction of the main RCA trunk. Therefore, we negotiated the septal channel; however, it could only be guided in the peripheral direction. When the guidewire was more advanced in the peripheral direction, it crossed the guidewire that had previously passed through the PL channel. Then, when a balloon was delivered via the septal channel and trapped the guidewire from the PL channel, the MC was successfully delivered via the PL channel. After establishing the retrograde system, revascularization succeeded smoothly. In conclusion, this technique can be one option for the treatment of CTO patients. <Learning objective: Even if a guidewire passes retrogradely, the establishment of the retrograde system may be difficult in some cases since the microcatheter cannot pass retrogradely. This technique can be one of the effective options for the treatment of patients with chronic total occlusion when establishing a retrograde system is difficult.>.

Chronic total occlusion percutaneous coronary intervention failure: Learning from failure

Experienced operators can achieve high success rates in chronic total occlusion percutaneous coronary intervention. Complications remain an important cause of chronic total occlusion intervention failure. Every effort should be made to prevent them and treat them appropriately should they occur. The most common failure mechanism for antegrade cases is failure to cross the occlusion with a guidewire. For retrograde cases the causes of failure are inability to cross the collateral (one third), inability to perform reverse CART (one third), and inability to cross with a microcatheter after guidewire crossing (one third).