The Learning Curves for Transradial and Ultrasound-Guided Arterial Access: An Analysis of the SURF Trial

Historically, coronary angiography and percutaneous coronary intervention involved accessing the femoral artery via palpation. However, recently there has been a trend towards using a transradial approach and ultrasound guidance for arterial access. Studies have shown that these techniques respectively improve major bleeding rates and access outcomes. There have been no studies conducted that assess the time it takes to train operators to attain proficiency. This sub-analysis of the Standard versus Ultrasound-guided Radial and Femoral access in coronary angiography and intervention (SURF) trial aims to assess the number of procedures required to attain proficiency in ultrasound-guided transradial and transfemoral access.

The SURF trial randomised 1,388 patients undergoing coronary angiography and/or percutaneous coronary intervention into standard or ultrasound-guidance and radial or femoral access in a 2×2 factorial design. Operators who participated in this trial were required to have performed at least 50 standard and 10 ultrasound-guided punctures for each of transradial and transfemoral access. Cases were then chronologically ordered and stratified into groups of five, from which the primary endpoint measured was a progression in mean access time and first-pass success rates.

Across all operators, there was a reduction in mean access time between procedures one to five and six to 10 with ultrasound-guided femoral punctures (60.5 secs-51.5 secs, p=0.029) and between procedures 11 to 15 and 16 to 20 ultrasound-guided radial punctures (74s to 62.5 secs, p=0.082). This trend was more obvious in trainees, with significant reductions in mean access time between procedures one to five and six to 10 from 73.5 to 53.5 seconds (p<0.001) for ultrasound-guided femoral access and from 99.5 seconds to 60 seconds (p=0.024) for ultrasound-guided radial access. There were no trends with standard transradial access.

The numbers required to attain competency in ultrasound-guided femoral and radial access are 15 and 25 punctures, respectively. Fifty (50) punctures appear adequate for proficiency in a standard transradial approach. These numbers are useful in incorporating into training program for advanced trainees and interventionalists.