Simon Wilson (Royal Infirmary of Edinburgh, Edinburgh, UK) and others report in EuroIntervention that the use of a novel microcatheter with a guidewire locking mechanism (NHancer, Interventional Medical Device Solutions) was associated with a 85.9% overall technical success rate in patients with chronic total occlusions undergoing percutaneous coronary intervention (PCI). They add that use of the catheter, for chronic total occlusion PCI, may lead to improved primary wiring and procedural success rates.
The authors report that “despite considerable progress” in improving procedural outcomes of chronic total occlusion PCI, procedural difficulties persist and “the success rate of chronic total occlusion PCI remains less favourable than non-chronic total occlusion PCI”. The NHancer microcatheter, Wilson et al comment, has been designed to address the “common residual failure modes” that include the inability to cross the occlusion with a guidewire or to deliver equipment through the chronic total occlusion.
The microcatheter has a hydrophilic polymer coating to provide enhanced lubricity and to increase visibility and improve crossing. Noting that the NHancer has the “lowest crossing profile” of all the current commercially available microcatheters, the authors write: “A uniquely designed torquer on a compressible shaft allows any commercial 0.014inch guidewire and the microcatheter to be transiently locked in combination.” Locking, they note, may improve the “ability of the guidewire, acting in combination with the NHancer, to overcome fibrocalcific resistance”.
In the study, 92 unselected patients with chronic total occlusions underwent PCI with the NHancer microcatheter. The mean Japanese chronic total occlusion (J-CTO) score was 2.79, with 56.6% having a J-CTO score of ≥3.
“Overall technical success was 85.9% for the study group, 97.5% for patients with a J-CTO score of 0–2 and 76.9% for patients with a J-CTO score of 3–5. In 78 of the 79 cases of technical success, stent(s) were successfully implanted,” Wilson et al say. Furthermore, the NHancer was the only microcatheter required in 68.4% of all successful interventions and chronic total occlusion tortuosity was the only lesion characteristic associated with a reduced chance of technical success.
According to Wilson et al, there are three major steps towards successful chronic total occlusion revascularisation: guidewire crossing of chronic total occlusion cap (proximal or distal), guidewire crossing of the chronic total occlusion body and microcatheter (or equivalent) crossing of the chronic total occlusion. They found, in this study, that the NHancer assisted in overcoming at least one of these major steps towards successful revascularisation “in 85.9% of the total study population, irrespective of the final outcome”.
Concluding, the authors say: “Guidewire locking with this novel microcatheter assists penetration and crossing of fibrocalcific anatomy with a high degree of safety. Using this device in chronic total occlusion PCI may lead to improved primary wiring and overall procedural success rates.”
Wilson told Cardiovascular News that “a careful angiographic assessment is key” to ensuring good procedural outcomes in chronic total occlusion PCI, adding that particular attention should be given to “anatomical factors that translate into procedural complexity”. “It is important to understand that differentiated tasks require differentiated equipment and that, in the event of failure to progress, an early change of strategy is more likely to achieve a successful final outcome,” he said.