Distal radial access not better than conventional approach in preventing radial artery occlusion, DISCO RADIAL trial.

Although conventional transradial access (TRA) has been established as the gold standard for invasive coronary angiography and percutaneous interventions, radial artery occlusion (RAO) remains the "Achilles' heel" of this approach. Recently, distal radial access (DRA) has been promoted as a promising alternative access to minimize RAO risk. However a recent, randomised trial published in JACC Cardiovascular Interventions has shown that DRA and TRA have equally low RAO rates and crossover rates to another access strategy are higher with DRA.

Anatomical constraints may limit the clinical benefits of TRA, yielding a few complications, including RAO, a complex process involving several interplaying factors ultimately leading to thrombosis. RAO is by far the most frequent complication of TRA, with highest incidence in the first 24 hours and spontaneous recanalization at 30 days in about one-half of the patients.

Distal radial access (DRA) in the anatomical snuff box or the dorsum of the hand has emerged in the past few years as a promising alternative access to further reduce the risk for RAO because of the puncture site within the hand anastomotic network, which most likely ensures persistent blood flow in the radial artery.

A large-scale, international, randomized trial comparing RAO with TRA and DRA is yet lacking. Therefore the DISCO RADIAL trial was conducted to was to assess the superiority of DRA compared with conventional TRA with respect to forearm RAO. By including 1,307 patients, DISCO-RADIAL is the largest trial on this topic.

The primary endpoint was the incidence of forearm RAO assessed by vascular ultrasound at discharge. Secondary endpoints include crossover, hemostasis time, and access site–related complications.

The primary endpoint, which was forearm RAO at discharge, was not met, as no statistically significant difference was observed (TRA 0.91% vs dTRA 0.31%; P = 0.29).

Moreover, authors observed that crossover rates and radial artery spasm frequency were higher in the dTRA arm (3.5% vs 7.4%; P = 0.002; and 2.7% vs 5.4%; P = 0.015, respectively), whereas the median hemostasis time was shorter (180 vs 153 min; P < 0.001). The swiftness of the hemostasis process appears to be a major determinant of the very low rate of forearm RAO and represents one of the most appealing advantages of DRA over traditional TRA.

The results showed an exceptionally low incidence of primary endpoint in both groups, without a statistically significant difference between them, most likely because of type II error rate inflation. These results are in contrast to previous single centre comparisons of these two radial access approaches. One plusible reason may be the stringent apllication of best practices to lower the rate of complications with TRA.

Also, DRA was associated with twice the incidence of radial artery spasm but similar patient self-reported pain rating, thus reassuring against a more unpleasant experience with DRA.

Compared with conventional TRA, time to successfully achieving DRA was only slightly longer, while no differences were seen in procedural duration, use of contrast medium, and radiation dose.

In conclusion, dTRA could be considered as another step closer to RAO prevention. The dTRA for coronary procedures in combination with the systematic implementation of best practices for RAO prevention may be the final solution against RAO.

Source: JACC CI:

1. J Am Coll Cardiol Intv. 2022 Jun, 15 (12) 1202–1204

2. J Am Coll Cardiol Intv. 2022 Jun, 15 (12) 1191–1201