The Wrist Circumference-to-Body Mass Index Ratio for Preprocedural Risk Stratification of Radial Artery Spasm in Transradial Coronary Angiography and Percutaneous Coronary Intervention

<b>Objectives</b>: Radial artery spasm (RAS) is a common complication of transradial coronary angiography that may adversely affect procedural success and patient comfort. This study aimed to evaluate clinical, procedural, and anthropometric factors associated with RAS in patients undergoing elective transradial coronary angiography, with a particular focus on the wrist circumference-to-body mass index (WC/BMI) ratio as a novel predictor. <b>Methods</b>: A total of 466 patients who underwent elective coronary angiography via the right radial artery between January 2024 and December 2024 were included. All procedures were performed using a 6 Fr introducer sheath according to a standardized protocol. Radial artery spasm was clinically defined as operator resistance during catheter manipulation accompanied by patient-reported pain or marked discomfort in the accessed arm. Wrist circumference and body mass index were measured before the procedure, and the WC/BMI ratio was calculated. Radial artery diameter was assessed using ultrasonography. Variables associated with RAS were evaluated using univariable and multivariable logistic regression analyses. Due to collinearity between WC/BMI and radial artery diameter, two separate multivariable models were constructed. Discriminative performance was assessed using receiver operating characteristic (ROC) curve analysis. <b>Results</b>: Radial artery spasm occurred in 51 patients (10.9%). Patients who developed RAS had significantly lower WC/BMI ratios and smaller radial artery diameters compared with those without spasm (both <i>p</i> ≤ 0.001). In multivariable analysis, a lower WC/BMI ratio was independently associated with an increased risk of RAS (odds ratio [OR] 0.51 per 0.1-unit increase; 95% confidence interval [CI] 0.34-0.78; <i>p</i> = 0.002). Similarly, smaller radial artery diameter remained an independent predictor of RAS (OR 0.83 per 0.1 mm increase; 95% CI 0.75-0.92; <i>p</i> < 0.001). The area under the curve (AUC) was 0.651 for WC/BMI and 0.636 for radial artery diameter. The combined model demonstrated improved discriminative ability (AUC 0.713). <b>Conclusions</b>: The WC/BMI ratio is a simple, practical, and readily obtainable anthropometric parameter that can predict the risk of radial artery spasm before transradial coronary angiography. When combined with radial artery diameter, it provides improved discrimination for identifying patients at higher risk of RAS.