DIStal Versus COnventional Radial Access for COMPLEX Large-bore Percutaneous Coronary Intervention (DISCO COMPLEX)

The radial artery has become the standard vascular access site for most percutaneous coronary interventions (PCI) and is recommended by the most recent 2018 European Society of Cardiology/European Association for Cardio-Thoracic Surgery guidelines on myocardial revascularization, irrespective of clinical presentation. Patients undergoing PCI of complex coronary lesions, such as a chronic total occlusion (CTO), left main (LM) coronary artery disease, complex bifurcation lesions, or heavily calcified lesions, have however been either absent or under-represented in most trials supporting these guidelines.

The small size of the radial artery remains an important limitation for the use of large bore guiding catheters (>6 F), restricting thereby the treatment of highly complex lesions through the transradial approach. The 7F GLIDESHEATH SLENDER® (Terumo Corp., Tokyo, Japan) is a dedicated radial sheath with a thinner wall and hydrophilic coating. It combines an inner diameter compatible with any 7F guiding catheter and an outer diameter smaller than current 7F sheaths.

A prospective, multicenter, observational study including 60 patients demonstrates that a transradial access (TRA) using the 7F GLIDESHEATH SLENDER® (Terumo Corp., Tokyo, Japan) for complex coronary interventions is feasible and associated with a high rate of procedural success and a low rate of vascular complications.

In the Complex Large-Bore Radial Percutaneous Coronary Intervention (COLOR) randomized trial, 388 patients with planned PCI for complex coronary lesions were randomly allocated to a 7F TRA or 7F transfemoral access (TFA). Conventional TRA was associated with a significant reduction in clinically relevant access- site bleeding or vascular complications without affecting procedural success when compared to TFA among patients undergoing complex PCI with a 7F large bore access.

The use of the distal radial artery has recently emerged as a promising alternative access route to further reduce the risk of radial artery occlusion (RAO) and has been endorsed by recent International Consensus documents. The feasibility of a distal radial access (DRA) for coronary angiography and/or PCI has been demonstrated in several observational clinical registries and small-sized randomized clinical trials. In the recent prospective, multicenter, open label, randomized, controlled DIStal vs Conventional RADIAL access (DISCO RADIAL) trial, DRA was associated with low and similar rates of RAO at discharge when compared to conventional TRA among patients undergoing coronary angiography and/or PCI. There is however limited evidence on the feasibility and safety of 7F DRA for PCI. The potential advantages of DRA when compared to TRA are contrasted by a slightly smaller size of the distal radial artery potentially impacting on device selection and procedural planning and by its less predictable course, due to the pronounced tortuosity and angulation of the vessel, leading to an overall higher number of puncture attempts, a longer time to achieve arterial access and a higher rate of access failure. These limitations may preclude the use of DRA for PCI of complex coronary lesions when a large bore guiding catheter is needed. There is however limited evidence on the feasibility and safety of 7F DRA for PCI.