Safety and Efficacy of Topical Nitroglycerin for Radial Artery Dilation (The RADial Trial): A Randomized, Placebo‐Controlled, Double‐Blind Clinical Trial

Background Transradial coronary catheterization is associated with a reduced risk of bleeding and vascular complications. Prior studies have evaluated nitroglycerin to improve transradial access by vasodilating the radial artery, but the optimal route of administration for preprocedural arterial dilation remains unclear. Methods In the RADial Trial (Radial Artery Dilatation Trial) patients undergoing transradial coronary catheterization were randomized in a double‐blind fashion to receive either a placebo or topical nitroglycerin ointment (nitropaste). The primary outcome was the mean change in radial artery dimensions, assessed using paired t tests. Categorical outcomes were analyzed using odds ratio (OR) with 95% CI. Results A total of 260 patients (130 placebo, 130 nitroglycerin) were enrolled. Nitropaste significantly increased the mean diameter (2.65±0.6 versus 2.48±0.6 mm), circumference (8.37±1.63 versus 7.77±1.66) and cross‐sectional area (5.63±2.28 versus 4.94±2.0 mm) of the radial artery, whereas no significant difference was observed in the placebo arm. Nitropaste was associated with a significant reduction in the number of skin punctures and risk of vasospasm (OR 0.34 [95% CI, 0.13–0.91], P =0.04). There was no significant difference between nitropaste and placebo groups in the odds of hematoma (OR, 0.32 [95% CI, 0.03–3.1], P =0.61), crossover to femoral access (OR, 2.29 [95% CI, 0.9–5.8], P =0.12), need for ultrasound‐guided access (OR, 0.39 [95% CI, 0.13–1.15], P =0.13), and hypotension or headache (OR, 1.5 [95% CI, 0.24–9.2], P =1.0). Conclusion Preprocedural administration of nitropaste significantly increases radial artery size and reduces the risk of vasospasm without causing headache or hypotension. Registration https://clinicaltrials.gov/study/NCT05239013