Illustration of a diverse group of people near a branching blood vessel, symbolizing heart health and the uncertainties of radial artery occlusion risks across ethnicities.

Radial Artery Occlusion: Is Ethnicity a Real Risk Factor?

Elliot Brynn in Health & Wellness August 2025 • 4 min read.

"Unpacking the complexities of RAO after heart catheterization and whether Japanese ethnicity truly increases the risk."

Radial artery occlusion (RAO) is a known complication following transradial heart catheterization, a common procedure where a catheter is inserted through the radial artery to reach the heart. Medical device companies have engineered slender sheaths, like the Glidesheath Slender series, to reduce the incidence of RAO by minimizing the profile of the inserted instruments. But how effective are these measures across different populations?

A study known as the Radial Artery Patency and Bleeding, Efficacy, Adverse evenT (RAP and BEAT) trial, sought to compare the efficacy of the 6Fr Glidesheath Slender with the standard 5Fr sheath in preventing RAO. While the initial results didn't establish the slender sheath's noninferiority, an intriguing subgroup analysis revealed a potential disparity between Japanese and non-Japanese participants.

In this analysis, Japanese patients experienced a higher incidence of RAO compared to their non-Japanese counterparts. Moreover, the 6Fr slender sheath appeared to be associated with a greater risk of RAO in Japanese patients, a finding that raises important questions about the role of ethnicity in vascular outcomes.

Decoding the Disparity: Is It Ethnicity or Other Factors?

Illustration of a diverse group of people near a branching blood vessel, symbolizing heart health and the uncertainties of radial artery occlusion risks across ethnicities.

The observation that Japanese participants in the RAP and BEAT trial had a higher incidence of RAO prompts a deeper investigation into the potential reasons behind this disparity. While ethnicity might seem like a straightforward explanation, it's essential to consider other variables that could be at play.

Several factors could contribute to the increased risk of RAO in Japanese patients, potentially confounding the role of ethnicity:

Smaller Radial Arteries: Japanese individuals tend to have smaller radial arteries compared to Caucasians. This could lead to a less favorable artery-to-sheath size ratio, increasing the risk of occlusion.
Repeated Interventions: Japanese participants were more likely to undergo a second radial intervention, which could independently increase the risk of RAO due to repeated trauma to the artery.
Antiplatelet Use: The use of antiplatelet medications, which help prevent blood clot formation, was lower in Japanese participants. This could be a contributing factor, as aspirin may prevent clot formation in the radial artery.
Prolonged Hemostasis: The duration of hemostasis, or the time it takes for bleeding to stop, was significantly longer in Japanese patients. Extended compression of the radial artery is a known risk factor for RAO.

Given these multiple, unbalanced factors between the two groups, it becomes challenging to isolate ethnicity as the sole determinant of RAO risk. Multivariable statistical adjustments may not fully account for the complex interplay of these confounders, making it difficult to definitively conclude whether Japanese ethnicity independently increases the risk of RAO.

The Verdict: Confounded or Real? What Does This Mean for You?

While the RAP and BEAT trial results suggest a potential association between Japanese ethnicity and a higher risk of RAO, the presence of multiple confounding factors makes it difficult to draw definitive conclusions. Further research is needed to disentangle the complex interplay of factors contributing to RAO and determine whether ethnicity truly plays an independent role.

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Everything You Need To Know

What is radial artery occlusion (RAO), and how does it relate to heart catheterization?

Radial artery occlusion (RAO) is a complication that can occur after a transradial heart catheterization procedure. This procedure involves inserting a catheter into the radial artery to access the heart. RAO happens when the radial artery becomes blocked after the procedure. Medical device companies have been developing solutions, such as the Glidesheath Slender series, which are designed to minimize the profile of the inserted instruments and potentially reduce the risk of RAO.

What was the RAP and BEAT trial, and why are the results significant regarding radial artery occlusion (RAO)?

The RAP and BEAT trial compared the effectiveness of the 6Fr Glidesheath Slender with the standard 5Fr sheath in preventing radial artery occlusion (RAO). While the initial results didn't confirm that the slender sheath was superior, a subgroup analysis pointed to a possible difference in RAO incidence between Japanese and non-Japanese participants. This is important because it suggests that ethnicity or other related factors might influence the risk of RAO after heart catheterization. Further studies are needed to understand the implications.

Besides ethnicity, what other factors could explain the higher incidence of radial artery occlusion (RAO) in Japanese patients?

Several factors could contribute to the increased risk of radial artery occlusion (RAO) observed in Japanese patients. These include anatomical differences like smaller radial arteries, a higher likelihood of undergoing repeated radial interventions, lower use of antiplatelet medications (like aspirin) to prevent blood clot formation, and longer hemostasis times (the time it takes for bleeding to stop). It is difficult to isolate any single factor, so these confounders make it challenging to definitively link Japanese ethnicity as the sole cause.

What are antiplatelet medications, and why is their use important in the context of radial artery occlusion (RAO)?

Antiplatelet medications, such as aspirin, are used to prevent blood clot formation. Their use is important because they can help prevent radial artery occlusion (RAO) after heart catheterization. The RAP and BEAT trial data showed that lower use of antiplatelet medications in Japanese patients may have contributed to the higher incidence of RAO. This highlights the importance of carefully managing antiplatelet therapy in patients undergoing transradial procedures.

Why is prolonged hemostasis a concern in the context of radial artery occlusion (RAO)?

Prolonged hemostasis, or the extended compression of the radial artery to stop bleeding after heart catheterization, can increase the risk of radial artery occlusion (RAO). The RAP and BEAT trial found that Japanese patients had significantly longer hemostasis times. This suggests that the duration of compression on the radial artery after the procedure is a risk factor for RAO, and techniques to minimize hemostasis time may be beneficial in reducing the risk of this complication.