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Refractory chronic total occlusions: A matter of definition…!

Historically, technical success rates for percutaneous coronary intervention in chronic total occlusions (CTOs) were quite low (40–57%) reflecting the lack of dedicated equipment as well as the lack of innovative techniques [1,2] However, CTO recanalization success rates have significantly increased over the last decade because of the introduction of dedicated stiff and tapered-tip wires as well as operator techniques and experience, such that successful recanalization of CTOs may now be achieved in about 80% of lesions [2]. Although reduced, failure at CTO recanalization using the CTO-dedicated guide wires still occur in at least 20% of patients [2]. Failure to recanalize a CTO is most often due to the inability to penetrate the proximal cap, although passage of the wire through a dissection plane or inability to renter the distal true lumen can also be reasons for failure. Theoretically, the ideal device to facilitate crossing of a CTO should have the capability to combine three key attributes: (1) precise detection of the entry site into the true lumen, (2) steerability in an adverse environment, and (3) the ability to advance through resistant plaque either mechanically or by using an active energy source. Several devices have been developed to address the problem of refractory CTOs, however, with less than optimal success. Among these devices are the Excimer laser wire (Spectranetics, Colorado Springs, CO), which was evaluated in a US-based registry [3] as well as a randomized trial [4], the Frontrunner catheter (Lumend, Redwood City, CA) [5], which was evaluated in a pre-approval as well as post approval registries, and the Safe Cross-RF guidewire (Intraluminal Therapeutics, Carlsbad, CA), which was evaluated in the Guided Radio Frequency Energy Ablation of Total Occlusions (GREAT) registry [6]. In this issue of the journal, Tiroc et al. [7] report the results of the FlowCardia Approach to Chronic Total Occlusion Recanalization (FACTOR) study which evaluated a novel high-frequency vibration catheter (The CROSSER device; FlowCardia, Sunnyvale, CA). In this registry, the CROSSER catheter was used in 125 patients who underwent failed CTO recanalization attempts using conventional guide wires in the recent past or during the index procedure. In this study, the CROSSER-assisted guide wire recanalization success rate was 60.8% and procedural success (achieving <50% diameter stenosis with TIMI II or III flow) was attained in 54.4% of patients. Major in-hospital adverse events occurred in 8.8% of patients. The authors conclude that high-frequency vibration using the CROSSER catheter is a safe and effective therapy for patients with CTO who are refractory to standard guide wire recanalization.