Predictors of radial artery size in patients undergoing cardiac catheterization: insights from the Good Radial Artery Size Prediction (GRASP) study

Background: Radial artery occlusion occurs after transradial cardiac catheterization or percutaneous coronary intervention. Although use of a sheath larger than the artery is a risk factor for radial artery occlusion, radial artery size is not routinely measured. We aimed to identify bedside predictors of radial artery diameter.

Methods: Using ultrasound, we prospectively measured radial, ulnar, and brachial artery diameters of 130 patients who presented for elective percutaneous coronary intervention or diagnostic angiography. Using prespecified candidate variables we used multivariable linear regression to identify predictors of radial artery diameter.

Results: Mean internal diameters of the right radial, ulnar, and brachial arteries were 2.44 ± 0.60, 2.14 ± 0.53, and 4.50 ± 0.88 mm, respectively. Results for the left arm were similar. The right radial artery was larger in men than in women (2.59 vs 1.91 mm; P < 0.001) and smaller in patients of South Asian descent (2.00 vs 2.52 mm; P < 0.001). Radial artery diameter correlated with wrist circumference (r(2) = 0.26; P < 0.001) and shoe size (r(2) = 0.25; P < 0.001) and weakly correlated with height (r(2) = 0.14; P < 0.001), weight (r(2) = 0.18; P < 0.001), body mass index (r(2) = 0.07; P = 0.002), and body surface area (r(2) = 0.22; P < 0.001). The independent predictors of a larger radial artery were wrist circumference (r(2) = 0.26; P < 0.001), male sex (r(2) = 0.06; P < 0.001), and non-South Asian ancestry (r(2) = 0.05; P = 0.006; final model r(2) = 0.37; P < 0.001). A risk score using these variables predicted radial artery diameter (c-statistic, 0.71).

Conclusions: Wrist circumference, male sex, and non-South Asian ancestry are independent predictors of increased radial artery diameter. A risk score using these variables can identify patients with small radial arteries.