Radial artery cardiac catheterization: changing the convincing data/work to change (CD/WC) ratio.

Cardiac catheterization is one of the commonest procedures done worldwide. Although the risks of the procedure are small, it is plagued by patient dissatisfaction due to the prolonged bed rest after the procedure and groin bleeding related to the femoral artery puncture site. There have been many attempts to decrease or eliminate the bed rest postprocedure, including the development of numerous percutaneous vascular closure devices, using smaller catheters and hemostatic patches. Although these devices in general achieve faster ambulation time, none have been shown to decrease bleeding complications and they all add cost to the procedure [1–4]. Radial artery catheterization offers the unique combination of less bleeding, better patient satisfaction and early ambulation without an increased cost to the system [5–7]. Despite these advantages, radial access has been very slowly adopted. Interventionalists have quickly adopted many new techniques that were shown to benefit patients, so why not the radial approach to cardiac catheterization? The best answer may be the convincing data/ work to change (CD/WC) ratio. I would propose this as a novel barometer of predicting when there will be a shift in medical practice. Physicians will rarely change their way of doing things until the CD/WC ratio is significantly greater than 1. If we look at recent new techniques in interventional cardiology, we can see how the CD/WC ratio affects practices. One the quickest changes that occurred in interventional cardiology was the adoption of drug eluting stents (DES). The randomized data for the prevention of re-stenosis was overwhelming [8] and the techniques needed to adapt to this change were no different than using bare metal stents. This gave DES a CD/WC ratio much greater than one. On the opposite side is the use of rotational and directional atherectomy. Here there is limited data in randomized trials of any patient benefit [9] and these procedures require a significant amount of training and new techniques to be successful. So the CD/ /WC ratio is less than one with atherectomy; therefore a cardiologist’s use of these devices is limited. So what is the CD/WC ratio of radial artery catheterization? At this point it is approaching 1 but not close enough for interventionalists worldwide to change their approach in large numbers. Decreasing the work to change (WC) is the first barrier that has to be overcome. Because of the radial artery’s small size, vascular anomalies and its tendency to spasm reaching the central aorta can be difficult. But with appropriate training and experience, success rates with the radial technique can approach the rates with femoral cases, even in complex patients [10, 11]. In addition to better training, better equipment is also making the technique less difficult. With new sheaths for radial access, better catheters for guide support and lower profile balloons and stents, never before has radial access been easier. The more operators adopt the radial technique, the more the medical device industry will improve the tools we use. Despite these advances it is unlikely that there will be a large decrease in the WC, so if the CD/ /WC ratio is going to be greater than 1, there needs