Less Occlusion, Hematomas With Distal Radial Access: Meta-analysis

Coronary access via the distal radial artery for interventional procedures reduces the risk of arterial occlusion and higher-grade hematomas compared with the traditional radial approach, according to results of a new meta-analysis.

The benefits, though, come at a price.

The distal approach was associated with greater challenges accessing the radial artery, which was highlighted by the longer times to radial puncture and sheath insertion, more puncture attempts, and higher rates of access-site crossover, according to lead investigator Giuseppe Ferrante, MD, PhD (Humanitas University, Pieve Emanuele, Italy), and colleagues.

The researchers say the meta-analysis, published online ahead of the November 28, 2022, issue of JACC: Cardiovascular Interventions, highlights the “current limitations” of the technique, which are likely attributable to operators not being completely proficient yet.

“All the limitations are actionable and may be overcome by a proper learning curve,” Ferrante told TCTMD. “It’s not a reason to not develop and implement the technique. Instead, we think the main issue we have now for not using distal radial access as the default approach is that the evidence from clinical studies doesn’t provide us with clear information about the impact on strong clinical endpoints.”

Conventional radial access, in contrast, has a lot of evidence behind it, including data from multiple clinical trials showing that its use is associated with a lower risk of death, major adverse cardiovascular events, major bleeding, and vascular complications in a wide range of patients with coronary artery disease. Based on the strength of these data, the 2021 US guidelines for coronary revascularization recommend radial access for all patients, as do the 2018 European guidelines.

“We don’t have this type of information from randomized clinical studies with the distal radial approach,” said Ferrante.

Ethan C. Korngold, MD (Providence Heart Clinic, Portland, OR), who wasn’t involved in the study, said one of the reasons for wanting to avoid radial artery occlusion (RAO) is that many patients are undergoing multiple procedures over a lifetime. RAO can limit future percutaneous interventions and may even eliminate the radial artery as a potential conduit for CABG surgery. In general, rates of RAO are low with both conventional and distal radial access these days, “but it does seem that the radial artery occlusion rates might be less with distal radial access,” he told TCTMD. “If there is occlusion, it happens distally so it’s less impactful to the hand.”

His own experience also suggests there is a benefit when it comes to reducing the risk of hematomas. “I can tell you, anecdotally, that I get less calls to the postprocedure unit to evaluate arm or wrist hematomas when I’m doing distal radial [procedures].”

Korngold said he believes, in general, that starting with the distal radial approach is a good option for a lot of patients, noting that it can be routinely used by operators once they gain some experience.

“One of the shifts that is essential is that you really need to use ultrasound for every access,” said Korngold. “I don’t think a lot of [conventional] radial operators are using ultrasound for their access, but if you shift to distal radial you really need to commit to using it. A hockey stick probe is great if you have it, but you can also get good images if you don’t have one. I think there’s certainly a learning curve. I’d probably estimate that it takes around 20 to 40 cases in order to get comfortable with it, but it’s something that’s learnable and repeatable.”

Ferrante agreed that ultrasound may be useful in distal radial cases, particularly if the radial artery is very small and tortuous.

Aiming to Lower Risk of RAO

The distal radial technique emerged as an alternative access site to lower the risk of RAO, which one meta-analysis suggested was 7.7% with conventional radial access. With this technique, a puncture is made distal to the superficial palmar arch from the anatomical “snuff box” on the dorsal side of the hand. The distal approach preserves anterograde flow in the forearm during compression, with the idea being there will be less risk of thrombus formation and RAO.

It’s the nondominant hand, the catheters tend to engage very easily from the left subclavian artery, and it’s just a nice thing for patient comfort. Ethan C. Korngold

Despite the concerns, the randomized DISCO RADIAL trial showed there was no significant advantage to using the distal approach over conventional radial access when it came to reducing the risk of RAO. In that trial, operators adopted “best practices” using the PROPHET protocol, which includes prophylactic ipsilateral ulnar compression during hemostasis, and reported radial occlusion rates of less than 1% in both the conventional and distal radial treatment arms.

To get a better understanding of the overall RAO risk with both access sites, the researchers performed a meta-analysis of 6,208 patients undergoing coronary angiography and/or PCI in 14 randomized, controlled trials. Of these trials, coronary angiography alone was performed in three studies while PCI was performed in 24% to 100% of patients in the others. The proportion of patients with ACS ranged from 14% to 100%.

Distal radial artery access was associated with a significantly lower risk of RAO at follow-up (risk ratio 0.36; 95% CI 0.23-0.56), in-hospital RAO (RR 0.32; 95% CI 0.19-0.53), and EASY ≥ II hematoma (RR 0.51; 95% CI 0.27-0.96) when compared with conventional radial access. Despite those benefits, the distal approach was associated with longer times to radial artery puncture and for sheath insertion, as well as a greater number of puncture attempts. Additionally, access-site crossover was more than threefold higher with distal radial access (12.5% vs 3.8%; P < 0.001). Fluoroscopy times, contrast volume, and time to hemostasis did not differ between the two approaches.

One of the limitations of the meta-analysis is that researchers were unable to perform subgroup analyses to identify patients who might benefit the most from distal radial access. Also, the trials were largely conducted in patients with chronic coronary syndrome, and the results might not be generalizable to the ACS setting.

Finally, Ferrante noted that the rates of RAO varied widely in the trials, with an average pooled crude event rate of 5.5%.

“It’s probably because there was a lack of systematic implementation of best practices for the prevention of radial arterial occlusion,” he said. “I suspect that our finding might suffer from this limitation, with some amplification of the true effect of distal radial compared with conventional radial on the incidence of radial artery occlusion.”

Distal Radial Access is Suddenly Cool

In an editorial, Matthew Tomey, MD, and Jacqueline Tamis-Holland, MD (Icahn School of Medicine at Mount Sinai, New York, NY), state that RAO is a common nonbleeding vascular complication with radial access, and while it’s seldom symptomatic and does not affect function, it should be avoided. Vasodilator cocktails, adequate procedural anticoagulation, specialized sheaths, patent hemostasis, and ipsilateral compression of the ulnar artery have all been put forth as ways to reduce the risk.

Distal radial access is another one of the tools, they add, noting that it’s been sensationalized a little bit on social media. The approach, say Tomey and Tamis-Holland, has a cool factor associated with it, but the meta-analysis does suggest that the risk of RAO is lower with distal radial access.

The downside is the time required to gain access. This might not matter as much in chronic coronary syndromes cases, but time is a factor in ACS, they note, stating that before the distal approach can be endorsed in ACS, dedicated trials will be needed.

“The findings of this meta-analysis serve not to dismiss the approach as overly difficult but rather to challenge the interventional community to confront its learning curve,” write Tomey and Tamis-Holland, noting that it’s “conceivable” that ultrasound could flatten the learning curve and improve ease of access. “A key question is whether the promise of reduced RAO and EASY ≥ grade II hematomas justifies anticipated additions to time and perhaps patient inconvenience as the interventional community climbs the learning curve of distal radial arterial access.”

To TCTMD, Ferrante said that their high-volume center has adopted the distal radial technique for chronic coronary syndrome cases, particularly for interventions done from the left side. With ACS, especially STEMI, they will do the case via the conventional radial approach because of the longer time needed for access. There are no data yet showing that the extra couple of minutes required to reach the culprit artery with distal radial access doesn’t negatively impact clinical outcomes, said Ferrante.  

“This is an issue that should be addressed in future studies,” he said. “We need more evidence in order to support [distal radial] arterial access in this specific setting.”

While distal radial access might be having a moment, Korngold said he believes the approach is truly useful in clinical practice, adding that anything that increases radial adoption over femoral access is good for patient outcomes. He added that the distal radial approach is easier for the patient and operator if doing the procedure from the left side.

“Increasingly in patients, we’re doing left radial access in those who have had a previous [left internal mammary artery graft] and this makes cannulation of the LIMA very easy and straightforward,” said Korngold. “I’ve been doing left distal radial as my primary access for most patients coming to the cath lab. It’s the nondominant hand, the catheters tend to engage very easily from the left subclavian artery, and it’s just a nice thing for patient comfort.”