By Sandeep Nathan
Numerous studies have indicated that the transradial approach confers benefit over the transfemoral approach for cardiac catheterisations and percutaneous coronary intervention (PCI).1-4 The latest of these studies, DRAGON, showed that a transradial approach was non-inferior to a transfemoral approach and was associated with a significantly higher rate freedom from bleeding events.5 This commentary explores why the USA, despite the aforementioned data, has been more reluctant than other countries to adopt the transradial approach.
The transradial approach remains far less commonly employed than the conventional transfemoral approach in cath labs across the USA. This practice pattern is considerably disparate from that of much of the global international interventional community. While fully understanding the complex and nuanced reasons for this difference may be impossible, a significant contributor to the observed disparity may simply be a matter of training. Japanese cardiologists, for example, are now routinely trained in radial approaches at high-volume centres, and so you can understand why the transradial approach is used in ≥50% of cases per centre in the Japan. In contrast, of the approximately 3 million catheter-based procedures performed annually in the USA, the transradial approach is only used in a quarter (or less) of them. Therefore, slow adoption of this arguably better procedure may follow from a historical relative lack of appropriate training resources and may be further influenced by a lower average number of procedures performed by US operators compared with their Asian, Canadian and European counterparts, falling PCI volume and a greater density of catheterisation laboratories per capita in the US than most peer nations.
Certain perceptual barriers may also limit the wider adoption of the approach. Some have argued that the training necessary to successfully incorporate radial approach into routine practice might outweigh the benefits vis-à-vis additional time spent (and consequently productivity lost) gaining proficiency commensurate with existing transfemoral skills. Furthermore, concerns over technical difficulties—such as radial spasm, tortuosity and vascular anomalies—may also challenge wide adoption. Perhaps most legitimately, radial artery occlusions can occur in 10% of cases or more,6-9 thus limiting radial re-access if future procedures are needed. Even in the absence of an occlusion, radial sheath insertion may cause vascular trauma and/or discomfort, further limiting repeat usage. In a clinical trial of 812 patients undergoing 1,539 transradial procedures, Sakai et al reported a positive correlation between the number of procedures and probability of technical failure of radial access.10 Of particular interest, the authors noted that vessel narrowing or occlusion was the primary underlying mechanism of technical failure at the time of radial re-access attempts. A separate linear regression analysis estimated a 5% failure rate associated with successive attempts at radial access procedures.11
However, while many of the aforementioned arguments against the transradial approach are valid on some level, with proper training, practice and observance of radial “best practices”, most if not all of these issues are surmountable—in particular the issue of radial artery occlusion—thus, rendering the transradial approach more predictable and efficient while preserving the option of radial access. Most instances of radial artery occlusion are asymptomatic and, therefore, are not detected. In the small minority of patients who are symptomatic, the majority of radial artery occlusion cases are self-limited. Furthermore, a number of recent publications have explored short-term systemic anticoagulation and graded homolateral ulnar compression as potential therapies for this complication when it is detected early. With respect to the transradial procedure as a whole, then, institution of evidence-based practices designed to maximise efficiencies, quickly traverse technical hurdles and limit the probability of radial artery occlusion, along with measures designed to treat it should it occur, may hold the key to wider transradial adoption in the USA. In our institutional experience, establishment of a comprehensive written protocol that includes planning and pre-procedural measures, periprocedural steps, and evidence-based practices at the conclusion of the procedure, have helped to limit the occurrence of radial artery occlusion to rates comparable to the lowest rates in the published literature.
The data are clear that the transradial approach offers significant benefits over the transfemoral approach. While this technique is growing in popularity in the USA, it should be used more frequently than it currently is and should be considered the default approach as it is elsewhere in the world. Best practices, sourced from published data and practical training courses should be adopted and protocolised. Fortunately, live training opportunities such as ThinkRadial (Merit Medical) among other course offerings now exist and are available for interested interventional cardiologists to hone existing transradial skills and to gain proficiency in advanced techniques. Ultimately, the success or failure of transradial procedures hinge on an operator’s technical skillset, willingness to tackle challenges and an understanding of the risk factors for procedural complications along with the implementation of strategies intended to reduce and obviate those risks.
1.Nathan S, Rao SV. Radial versus femoral access for percutaneous coronary intervention: implications for vascular complications and bleeding. Curr Cardiol Rep. 2012;14:502-509.
2.Cooper CJ, El-Shiekh RA, Cohen DJ, et al. Effect of transradial access on quality of life and cost of cardiac catheterization: a randomized comparison. TR and Q of life. Am Heart J. 1999;138:430-436.
3.Jolly SS, Yusuf S, Cairns J, et al. Radial versus femoral access for coronary angiography and intervention in patients with acute coronary syndromes (RIVAL): a randomised, parallel group, multicentre trial. Lancet. 2011;377:1409-1420.
4. Valgimigli M, Gagnor A, Calabró P, et al. Radial versus femoral access in patients with acute coronary syndromes undergoing invasive management: a randomized multicentre trial. Lancet. 2015 Mar 13. pii: S0140- 6736(15)60292-6. doi: 10.1016/S0140-6736(15)60292-6. [Epub ahead of print].
5. DRAGON study reference. Presented at TCT.
6. Kotowycz MA, Dzavík V. Radial artery patency after transradial catheterization. Circ Cardiovasc Interv. 2012;5:127-133.
7. Stella PR, Kiemeneij F, Laarman GJ, et al. Incidence and outcome of radial artery occlusion following transradial artery coronary angioplasty. Cathet Cardiovasc Diagn. 1997;40:156-158.
8. Uhlemann M, Möbius-Winkler S, Mende M, et al. The Leipzig prospective vascular ultrasound registry in radial artery catheterization. Impact of sheath size on vascular complications. J Am Coll Cardiol Cardiovasc Interv. 2012;5:36-43.
9. Rao SV. Observations from a transradial registry: our remedies oft in ourselves do lie. J Am Coll Cardiol Cardiovasc Interv. 2012;5:44-46.
10. Sakai H, Ikeda S, Harada T, et al. Limitations of successive transradial approach in the same arm: the Japanese experience. Catheter Cardiovasc Interv. 2001;54:204-208.
11. Abdelaal E, Molin P, Plourde G, et al. Successive transradial access for coronary procedures: experience of Quebec Heart-Lung Institute. Am Heart J. 2013;165:325-331.
Sandeep Nathan, University of Chicago Medicine, Section of Cardiology in Chicago, USA. He has disclosed that he has served as a consultant to Medtronic, Terumo Interventional Systems, and Merit Medical.