Abstract: Objective To evaluate the efficacy and safety of coronary angiography or percutaneous coronary intervention (CAG/PCI) performed via distal transradial access (dTRA) using a 7Fr thin-walled sheath.Methods In this single-center prospective observational study, a total of 332 patients at Xuzhou Central Hospital from September 2024 to February 2025 were consecutively enrolled. Puncture and sheath insertion success rates were recorded. Color Doppler ultrasonography of the radial artery was performed at postoperative 24 h. The artery-to-sheath ratio (ASR; radial artery inner diameter/sheath outer diameter) and the incidence of radial artery occlusion (RAO) were evaluated.Results The success rate of dTRA puncture was 93.9% (336/358), and the success rate of 7Fr thin-walled sheath insertion was 92.7% (332/358). The incidence of early postoperative RAO was 3.3% (11 cases). Multivariate logistic regression analysis indicated that ASR<0.75 (OR=3.916, 95%CI 1.115-8.396, P=0.037) and diabetes mellitus (OR=1.535, 95%CI 1.048-2.248, P=0.028) were independent risk factors for early RAO. Receiver operating characteristic (ROC) curve analysis identified 0.665 as the optimal cutoff value of ASR for predicting RAO (AUC=0.821, 95%CI 0.727-0.910, P<0.01), with a sensitivity of 80.0% and a specificity of 82.7%.Conclusions The use of a 7Fr thin-walled sheath via dTRA for interventional diagnosis and treatment achieves a high procedural success rate with a low risk of RAO. However, patients with a distal radial artery inner diameter <1.86 mm (ASR<0.665) or concomitant diabetes have a significantly increased risk of RAO.