Slender Transradial PCI – How Small is Small Enough?

By Dr Giovanni Amoroso, Department of Cardiology, Onze Lieve Vrouwe Gasthuis, Amsterdam, The Netherlands.

Transradial approach (TRA) has shown to be as effective as transfemoral approach in cases of percutaneous coronary inteventions (PCI), but significantly safer in terms of access-site related complications. Therefore, TRA has become the standard of care in Europe and Asia, and is also propagating fast throughout the transfemoral-minded United States. The Achilles’ heel of TRA is the diameter of the radial artery, which is on average 3x smaller than the femoral artery. If we consider a 6 Fr introducer as the norm, 20%-40% of patients will have a radial artery smaller than that. This would not be the case for the femoral artery. Introducer/guiding catheter mismatch vs the radial artery will lead to higher procedural failure rates and/or vascular trauma, and in terms, to more postprocedural radial artery occlusions (RAO).(1) While RAO is rarely clinically relevant, it will however preclude the use of the radial artery for repeated procedures: a significant drawback for TRA.
To overcome this problem, Japanese cardiologists first, and European cardiologists later, felt the urge to initiate the Slender (R)evolution. The mission of both the Slender Club Japan and Europe is to demand, promote, and test catheters and devices, sufficiently miniaturized not to pose a danger anymore for the radial artery, but performant enough to provide the same outcomes after PCI.(2) The “virtual 3 Fr” guiding catheter (Medikit Co Ltd, Japan) is one of these. It consists basically of a 5 Fr guiding catheter, which can be introduced into the radial artery, without the need for an arterial sheath (the “sheathless” technique). Virtually no patient would have a radial artery smaller than this guiding catheter. Takeshita et al had already tested the feasibility of this guiding catheter in a Japanese population.(3) In our study, we confirmed these positive results in a Western population. Moreover, we could demonstrate that “virtual 3 Fr” guiding catheters, by drastically reducing hemostasis times, help prevent RAO and allow day-care PCI in the vast majority of patients. In particular, procedural success was 96% (25/26 lesions), and mean procedural time and contrast usage were 26 ± 15 minutes and 94 ± 69 mL, respectively. Patent hemostasis was successful in 10/11 patients, all patients were discharged home within 6 hours, and no acute RAO occurred.
Should we expect that Slender PCI techniques will soon go “mainstream,” such as TRA is doing? Probably not yet. First of all, the reproducibility of positive outcomes is determined by the learning curve. In our series, all procedures were conducted by the same operator, experienced both in TRA and “sheathless” techniques. Other operators would experience more difficulties with smaller catheters, mostly because of lack of support. To cope with that, one of the purposes of the Slender Club Europe will be to teach Slender techniques to peers by means of dedicated workshops. Secondly, the range of Slender materials is still not complete. In order to apply the Slender approach to more complex procedures (kissing techniques, acute PCI, chronic total occlusion), interventional devices need to be at least 5 Fr compatible (or less). The recent introduction of the Slender IDS (Svelte Medical Systems, New Jersey), the world’s lowest-profile drug-eluting stent, is an example of going in the correct direction.


  1. Garg N; Madan BK; Khanna R. Incidence and predictors of radial artery occlusion after transradial coronary angioplasty: Doppler-guided follow-up study. J Invasive Cardiol. 2015 Feb;27(2):106-12.
  2. Kiemeneij F; Yoshimachi F; Matsukage T. Focus on maximal miniaturisation of transradial coronary access materials and techniques by the Slender Club Japan and Europe: an overview and classification. EuroIntervention. 2015 Feb;10(10):1178-86.
  3. Takeshita S; Saito S. Transradial coronary intervention using a novel 5-Fr sheathless guiding catheter. Catheter Cardiovasc Interv. 2009 Nov 15;74(6):862-5.
  4. Stucchi Devito F; de Andrade PB;  Faria CE. Evaluation of the Safety and Efficacy of the Novel Svelte Acrobat Integrated Delivery System via Radial Approach With 5 Fr Catheters. J Invasive Cardiol. 2015;27(12):E312-E318.

Read Dr. Amoroso’s article on the safety and feasibility of “virtual 3 Fr” transradial percutaneous coronary intervention (TRA-PCI) in an outpatient setting in this month’s issue of the Journal of Invasive Cardiology.