Background

Transradial access (TRA) has become the default access route for coronary diagnostic and interventional procedures due to increased safety and a radial-first strategy is advocated by the most recent ESC/EACTS and ACC/AHA/SCAI guidelines. However, radial artery occlusion (RAO) remains the most frequent complication of TRA and precludes the use of the radial artery for future procedures, or as a conduit during coronary artery bypass grafting. Distal radial access (DRA) has recently emerged as an alternative vascular access route to reduce the risk of RAO because of a puncture site within the hand anastomotic network, which most likely ensures persistent blood flow in the radial artery. DRA is technically more challenging though than conventional TRA due the smaller size of the distal radial artery and its curvilinear course, with reported failure rates up to 30%. The DISCO RADIAL (Distal vs Conventional Radial Access) Study was initiated to compare TRA vs. DRA with respect to forearm RAO simultaneously implementing a best-practice rigorous haemostasis protocol in order to prevent RAO.

Methods

DISCO RADIAL was a multicenter, randomized, controlled study. Sites from Europe (15) and Japan (1) participated. Patients scheduled for a diagnostic coronary angiography or a percutaneous coronary intervention (PCI) were randomized between TRA and DRA. Patients presenting with a STEMI were excluded as well as PCI for chronic total occlusions. A series of RAO preventive measures were implemented for both groups including adequate anticoagulation, effective spasmolytic treatment, use of the 6 Fr Glidesheath Slender, patent haemostasis and the requirement that all operators were proficient in DRA. The primary endpoint was forearm RAO assessed by vascular ultrasound at discharge. A secondary objective was to identify predictors for cross-over in the DRA group. Cross-over was defined as failure to obtain access through the assigned access site. A stepwise logistic regression model was implemented including eleven variables identified from the literature known to be associated with cross-over after TRA: age, sex, BMI, active smoking, diabetes mellitus, diagnostic angiography vs PCI vs both, ACS vs CCS, previous procedure through the same radial artery, radial artery spasm, site in Europe vs Japan, and ultrasound-guided access.

Results

In total, 657 patients were assigned to TRA and 650 patients to DRA. The incidence of RAO at discharge was equally low for the TRA and DRA group: 0.91% vs 0.31% (p=0.29). Cross-over was more frequent with DRA (3.5% vs 7.4%, p=0.002) as well as the incidence of radial artery spasm (2.7% vs. 5.4%, p<0.015). Median haemostasis time was shorter with DRA (180 min. vs. 153 min., p<0.001). There was no difference in bleeding events and vascular complications between the groups. Radial artery spasm (OR 4.4 (95% CI 1.9-10.5), p<0.001) and female sex (OR 2.7 (95% CI 1.5-5.0), p<0.01) were associated with an increased risk for cross-over in the DRA group.

Conclusion

The incidence of forearm radial artery occlusion was equally low after transradial access and distal radial access. This very low radial artery occlusion rate is attributed to the haemostasis protocol and supports the implementation in daily clinical practice in which transradial access remains the gold-standard vascular access method. Distal radial access has a higher cross-over rate with female sex and radial artery spasms as risk factors.