Enhanced Antegrade CTO Revascularization Strategy: Notes on a Unique Microcatheter Technology

One hundred eighteen patients underwent CTO revascularization through enhanced antegrade recanalization technique utilizing a unique microcatheter device. Pre-procedure 77% of the CTOs exhibited a significant JCTO score predicting difficulties and risks of revascularization. A 94% PCI success rate and remarkably low complications were gained with the propriety microcatheter. The structure of the investigated microcatheter enhances guidewire stability and provides reliable support for antegrade penetration onto the proximal CTO cap as well as conversion to antegrade wire escalation and antegrade dissection re-entry. In an elegant paper published in this issue of the Journal, Ayoub and colleagues report a prospective multinational, multicenter study on coronary CTO [Chronic Total Occlusion] revascularization in a series of 118 patients who underwent PCI [Percutaneous Coronary Intervention] through enhanced antegrade recanalization technique utilizing a unique microcatheter device. Forty two percent of the target lesions were defined by the JCTO [Japanese Chronic Total Occlusion] score as difficult and 35% as very difficult, with a mean score of 2.16 ± 0.95. This implies that 77% of the study CTOs were predicted pre-procedure to exhibit significant challenge and risk for revascularization. The documented median procedure time of 90 min, fluoroscopy time 36.5 min, radiation dose 1011.5 miliGray units and contrast volume of 160 milliliters- are all within reasonable safety range. Comparing those patients whose procedure lasted longer than 90 min versus shorter, the former had significantly longer CTO lesions, higher JSCORE, necessitated application of more guidewires and stents, as well as requiring longer stents. The investigated microcatheter [ReCross, IMDS, Roden, The Netherlands] contains three guidewire exit ports, of which two side-exit ports are located near the distal tip. These side-exit ports are positioned with a 180° separation angle, an arrangement that improves guidewire maneuverability and provides a route for intra catheter wires exchange. These structural features enhance the microcatheter's stability within the treated vessel and lend strong physical support for antegrade penetration onto the proximal CTO cap and beyond. The operator can use any type of dedicated guidewire. In case of failed crossing this device enables conversion to other recanalization methods such as the antegrade wire escalation and antegrade dissection re-entry. Documenting an impressive PCI outcome, including 94% success rate and a remarkable low complications rate (only one distal wire perforation), this study corroborates contemporary views holding antegrade CTO recanalization with its benefits of decreased procedure duration, reduced radiation exposure and relatively low contrast load, as the predominant PCI strategy for complex CTO lesions [1]. Noteworthy, the investigators adhered to a consensus-based PCI algorithm which provides freedom of choice concerning guidewire type and the sequence of wiring techniques. Their experience supports this meticulous approach to CTO revascularization. The unique structure of the investigated microcatheter provides enhancement of antegrade guidewire penetration onto the CTO and enable conversion to wire escalation and dissection re-entry. The importance of incorporating imaging modalities such as OCT [optical coherence tomography] and IVUS [intravascular ultrasound] in CTO revascularization should be emphasized [2]. Indeed, integration of imaging modalities in 50% of the patients in the index series constitutes a significant improvement of utilization over that of previous PCIs studies, especially in CTO lesions. Surprisingly, the presence of thrombus within the CTO lesions was not reported among the imaging findings, yet, undoubtedly, it was there [3]. It should be recognized that organized thrombus (at times interspersed with fresh layers) is an integral histologic constituent that contributes to the composition of the CTO obstructions, in addition to the atherosclerotic plaque material, calcifications and fibrosis. Importantly, the thrombotic content of the CTO lesions develops intra thrombus penetrating microvascular channels which for the purpose of recanalization serve as “anatomical gates” that permit the introduction and facilitation of guidewire entry and advancement along the lesion. Accordingly, these unique histopathologic microstructures increase the likelihood of successful recanalization and achievement of adequate procedure outcomes [4]. Moreover, when large volume, obstructive thrombus resides in the CTO it can impede stent delivery and resist subsequent deployment. In this scenario pre-stenting thrombus debulking by means of mechanical thrombectomy devices is warranted [5]. Altogether, the PCI experience and data analysis as published by Ayoub and colleagues contribute to further understanding of the challenges surrounding CTO interventions as well as illuminating the applicability of various revascularization strategies, especially the enhanced antegrade methods. The author declares no conflicts of interest.