Abstract Body (Do not enter title and authors here): Background
Radial artery (RA) access has become common in cardiac catheterization due to fewer vascular complications and MACE compared to transfemoral approach (TFA). However, anatomic variations are more profound in the upper-extremity.

Research Question
What are common anatomic variations encountered during transradial approach (TRA) coronary angiography and what association do they have with adverse outcomes and procedural challenges?

Methods
We performed a single-center retrospective analysis of 926 patients who underwent coronary angiography through TRA via the right upper-extremity where RA angiogram was performed from 01/2010 to 01/2023. Multivariate logistic regression was utilized to estimate the odds ratio (OR) of the association between anatomic variations and adverse outcomes and procedural challenges.

Results
A total of 926 patients with a mean age of 59.9 years were studied with 30.4% being female. Common comorbidities were HTN (82.2%), HLD (51.8%), and DM (45%). About 32% of patients had an anatomic variation. Prevalences were 14.4% radial tortuosity, 12% high RA bifurcation, 11.9% M-sign, and 1% RA loops. These patients were older (P<0.001) and more likely to have HLD (P=0.049). They had high odds of high contrast dose (OR 1.73; 95% CI 1.28-2.34, P<0.001), long fluoroscopy time (OR 2.02; 95% CI 1.50-2.73, P<0.001), high radiation exposure (OR 2.47; 95% CI 1.79-3.42, P<0.001), difficulty engaging coronary arteries (OR 2.70; 95% CI 1.94-3.74, P<0.001), and transfer to TFA (OR 4.89; 95% CI 2.36-10.12, P<0.001). Females (OR 2.89; 95% CI 2.01-4.15, P<0.001), small RA size (OR 2.61; 95% CI 1.76-3.86, P<0.001), high RA bifurcation (OR 1.68; 95% CI 1.02-2.75, P=0.04), and M-sign (OR 2.04; 95% CI 1.24-3.35, P=0.005) were associated with RA spasm. Major complications were not significant.

Conclusion
We found a high prevalence of anatomic variations. They were associated with high odds of adverse outcomes and procedural challenges during TRA coronary angiography.