UltraSound Guided Distal Radial Artery vS Conventional Transradial Access for Interventional Coronary Angiography

Current European and American guidelines issued by the European Society of Cardiology (ESC), the American Heart Association (AHA), and the Society for Cardiovascular Angiography and Interventions (SCAI) recommend transradial access (TRA) as the preferred access route for cardiac catheterization in both acute and chronic coronary syndromes, as well as in complex coronary interventions. Compared with transfemoral access, transradial access has demonstrated significant benefits regarding vascular complications, major bleeding, mortality, and earlier mobilization and discharge of patients.

In recent years, access through the distal segment of the radial artery in the anatomical snuffbox has emerged as a technique with highly beneficial characteristics comparable to conventional radial access, while also offering additional advantages. The ANGIE study demonstrated that distal radial access was associated with a statistically significant reduction in radial artery occlusion compared with conventional radial puncture. Puncture of the distal radial artery preserves antegrade blood flow in the forearm during hemostatic compression, thereby reducing the risk of arterial occlusion.

Existing literature Although the benefit of distal radial access in preventing radial artery occlusion has now been established, the same does not apply to crossover incidence, namely the need to change to an alternative vascular access site because the intervention cannot be completed through the initially selected access.

Several studies have shown higher crossover rates with distal radial access compared with conventional radial access. In the study by Koutouzis et al., distal radial access failed more often, with a crossover incidence of 30% versus 2% in the conventional radial group. Similar findings were reported in the DAPRAO study, the ANGIE trial, the DISCO RADIAL trial, the CONDITION trial, and observational studies and meta-analyses. Overall, published evidence consistently suggests that distal radial access is associated with a higher likelihood of crossover than conventional radial access when performed without ultrasound guidance.

Aim and originality of the study A common characteristic of all the above studies is that the comparison between the two access techniques was performed using anatomical guidance rather than ultrasound guidance.

As noted in the SCAI recommendations, failure to catheterize the radial artery is the leading cause of transradial procedural failure. The radial artery is relatively small in diameter, may be calcified, or may present anatomical variations that complicate vascular access. Two-dimensional ultrasound may therefore be a valuable tool for pre-procedural planning and real-time guidance.

A large meta-analysis of 12 studies including 2,432 adults undergoing conventional transradial access under ultrasound guidance showed improved first-pass success rates and reduced access failure rates. Similarly, ultrasound-guided distal radial access significantly increased successful intervention rates in the study by Mori et al. Consequently, the purpose of the present study is to demonstrate ultrasound guidance as a technique capable of increasing successful completion rates for both vascular approaches, while establishing distal radial access as a non-inferior alternative to conventional radial access regarding crossover probability.

Methodology The study will be conducted after approval by the Scientific Council and the Ethics and Deontology Committee of the University General Hospital of Patras.

This is a prospective, randomized, single-center, non-inferiority clinical study that will be carried out in the Hemodynamic Laboratory of the Cardiology Department of the University General Hospital of Patras in collaboration with the Radiology Department.

Study population The control group will undergo coronary angiography through conventional transradial access (TRA). The intervention group will undergo coronary angiography through distal radial access (DRA). Radial artery puncture will be performed exclusively under ultrasound guidance. Patients meeting the inclusion criteria and none of the exclusion criteria will be randomized in a 1:1 ratio to DRA or TRA.

Arterial access procedure:

The procedure begins with sterilization of both potential puncture sites regardless of randomization group. Conventional radial artery puncture is performed approximately 2-3 cm proximal to the styloid process. In patients randomized to distal transradial access (dTRA), puncture is performed more distally in the anatomical snuffbox at an angle of 30-80 degrees.

The interventional cardiologist uses the ultrasound probe exclusively, covered with a sterile protective sheath, to identify anatomical landmarks, define a safe puncture site, and avoid injury to adjacent structures. Local lidocaine infiltration is then performed under ultrasound guidance. The intravascular position of the needle is confirmed by ultrasound visualization and continuous blood flow.

After successful puncture of the radial artery, a 6 French sheath is inserted using the Seldinger technique. Subsequently, 50 IU/kg unfractionated heparin is administered (100 IU/kg total dose in case of angioplasty), together with nitroglycerin according to standard practice.

Hemostasis procedure After completion of the procedure, a TR band device is used. Hemostasis is assessed at 0,5 ,1, 2, and 3 hours after placement of the device, and if hemostasis is not achieved within this timeframe, manual compression is applied.

Data collection

For all participants, the following will be recorded:

• Demographic characteristics, cardiovascular risk factors, medical history, and chronic medication
• Body weight and body mass index (BMI)
• Reason for catheterization (STEMI, NSTEMI, unstable angina, stable coronary artery disease, suspected coronary artery disease, or valvular disease)
• Periprocedural antiplatelet or anticoagulant therapy
• Laboratory tests: Ht, Hgb, PLT, WBC, Urea, Creatinine
• Allen test and quality of radial artery pulse
• Total puncture attempts and total time to achieve vascular access
• Fluoroscopy duration, total angiography time, and contrast volume
• Number and type of diagnostic catheters used
• Type of hemostatic device and duration of hemostasis Primary endpoint Need for vascular access crossover due to failed puncture, failed wire or sheath advancement, or inability to complete the procedure through the initial vascular access. The exact reason for crossover will be recorded.

Secondary endpoints

• Local hematoma classified according to EASY criteria
• Arterial spasm severity
• Sheath placement time
• Total procedural time
• Time from puncture initiation until completion of coronary angiography before PCI
• Time required for diagnostic coronary angiography after sheath placement
• Time required until PCI completion
• Total fluoroscopy time
• Total DAP
• Air Kerma
• Hemostasis duration
• Vascular complications (arterial perforation, pseudoaneurysm, arteriovenous fistula)
• Distal radial artery occlusion before discharge
• Bleeding events according to BARC classification