This prospective clinical study aims to investigate whether the puncture site distance from the radial styloid process affects the incidence of radial artery spasm (RAS) during coronary angiography. Patients undergoing coronary angiography via radial access will be randomized into two groups based on the puncture site distance: 0-20 mm and >21 mm from the styloid process. The procedure will be performed by experienced interventional cardiologists using standard techniques and medications. The primary goal is to determine if a specific puncture site reduces the incidence of RAS, which is a common complication during transradial procedures. The study will also record procedural details and monitor for other complications to identify the optimal puncture site for reducing RAS and improving patient comfort.

The transradial approach (TRA) is the standard vascular access route for diagnostic coronary angiography and percutaneous coronary interventions, in accordance with contemporary guidelines, due to lower bleeding risk, improved patient comfort, and facilitation of early mobilization compared with femoral access. Despite these advantages, radial artery spasm (RAS) remains a common and clinically relevant complication during transradial procedures, often associated with procedural difficulty, the need for access site crossover, and patient discomfort.

RAS is characterised by sudden, transient contraction of the radial artery during sheath insertion or catheter manipulation, which may result in difficulty in catheter advancement, and, in rare cases, procedural failure or catheter entrapment. Several clinical and procedural factors have been identified as being associated with the development of RAS, including female sex, smaller arterial diameter, use of larger sheaths, inadequate sedation, and limited operator experience. Currently radial access is recommended near the styloid process but there is limited data on the effects of different puncture distances from the styloid process on the development of RAS. We examined the impact of different radial artery puncture distances from the styloid process, on the development of radial artery spasm and access-site-related complications.

Inclusion Criteria:

Adults aged 18 years and older. Patients scheduled for coronary angiography via transradial access. Patients with a palpable radial artery pulse. Patients with a normal Allen test.

Exclusion Criteria:

Abnormal Allen test results. Absence of palpable radial artery pulse. History of prior transradial coronary angiography with hemodynamic instability. Patients with severe comorbid conditions precluding safe participation in the study.

Individual participant data (IPD) will not be shared because the study is a single-center observational procedural study with limited resources for external data sharing and monitoring. Data can be shared upon reasonable request to the principal investigator in compliance with local regulations.