Introduction: Transradial access, or forearm artery access (FAA) in general, has established itself as the preferred arterial access for cardiac catheterization. Difficult vascular anatomy (DVA) is a noticeable threat to procedural success. 

Methods: We retrospectively analyzed 1397 consecutive procedures of cardiac catheterization to estimate the prevalence and identify predictors of DVA.

Results: Severe DVA, causing procedural failure, was found in 2.5% of procedures at the right forearm vs. in 1.7% at the left forearm (χ2=0.77, p=0.38), and in 2.4% at the right upper arm vs. 0.7% at the left upper arm (χ2=5.1, p=0.023). Bilateral severe DVA was found in 0.9% of patients. In multivariate analysis, advanced age (odds ratio (OR) 1.025/year of age, 95% confidence interval (CI) 1.001 to 1.049, p=0.039), lower height (OR 0.957/cm, 95% CI 0.927 to 0.988, p=0.008) and left FAA (OR 2.087, 95% CI 1.413 to 3.084, p<0.001) were found to be independent predictors of DVA at the forearm. At the upper arm, independent predictors were advanced age (OR 1.037/year of age, 95% CI 1.014 to 1.060, p=0.001) and right FAA (OR 2.519, 95% CI 1.718 to 3.690, p<0.001). 

Conclusion: The prevalence of severe DVA at one arm was relevant but severe bilateral DVA was rare. At the upper arm, right FAA and advanced age and at the forearm left FAA, advanced age and lower height were predictors of DVA. Gender, arterial hypertension, body mass, and smoking were not associated with DVA. Left FAA might be preferable to right FAA for coronary access in cardiac catheterization.