Transradial (TR) access for percutaneous coronary procedures reduces vascular complications and bleeding, and thus improves clinical outcomes compared to the transfemoral (TF) approach. Yet, radial access is underutilized in clinical practice in many countries including the United States. This is primarily due to technical complexities related to the smaller caliber of the artery and more difficult catheter manipulations due to frequently encountered anatomical variants of the upper arm arterial axis from the wrist to the aorta. The TR approach requires a steeper learning curve of approximately 50 cases, and is associated with higher access crossover rates compared to the transfemoral approach. Anticipation and recognition of procedural difficulties and failure are critical issues during TR procedures.
The frequency of failure to perform percutaneous coronary interventions (PCI) via radial access has been estimated at approximately 6% according to meta-analyses, including studies performed more than a decade ago. However, access crossover rates can be as high as 12.3% especially in the hands of inexperienced operators. In addition, access crossover has been reported to be higher in the TR group (up to 17.2%) compared with femoral access during coronary angiography in patients who had undergone coronary artery bypass grafting (CABG). A more recent study from an experienced group from Laval University in Quebec, Canada reported very low technical TR PCI failures with a TF crossover rate of only 1.8%. This low crossover rate is probably due to the fact that operators crossed over to the contralateral radial artery before attempting femoral access. Factors associated with TR failure included female gender, cardiogenic shock, and previous CABG.