Transradial PCI Bests Femoral Access in Complex Cases: COLOR

Treating chronic total occlusions (CTOs), complex bifurcations, heavily calcified lesions, and left main coronary artery disease with large-bore catheters via the radial artery is associated with significantly less access-site bleeding and fewer vascular complications when compared with femoral access, according to the results of the COLOR study.

Researchers say the findings lend further support to performing PCI via the radial artery, this time in the types of complex coronary lesions that have typically been excluded from randomized clinical trials.

“I hope that physicians who are still femoral artery-oriented for complex PCI should move on and use this data to start performing CTOs and other complex procedures with radial access in order to treat these patients safer,” senior investigator Maarten van Leeuwen, MD, PhD (Isala Heart Center, Zwolle, the Netherlands), told TCTMD.  

Lead investigator Thomas Meijers, MD (Isala Heart Center), who presented the results at EuroPCR 2021, said the COLOR trial with slender 7-Fr guide catheters for complex cases shows that the overall safety of the procedure can be improved without comprising procedural success.

The radial artery is the recommended access route for diagnostic and interventional procedures in the European and American guidelines based on a wealth of data showing that the transradial approach is associated with a lower likelihood of access-site bleeding and vascular complications. There also is evidence showing that radial access is associated with a lower risk of mortality, as reported in RIFLE-STEACS and MATRIX.

However, operators may choose to go with transfemoral access in complex cases where large-bore guiding catheters (≥ 7-Fr) are needed, and there are concerns about sheath-to-artery mismatch that can result in vasospasm or vascular and bleeding complications, said van Leeuwen. In one study, use of large guide catheters through the radial artery was linked to an increased risk of radial artery occlusion. For those reasons, use of the radial artery for complex cases varies across centers, countries, operators, and younger and older generations of physicians, he said.

For a lot of operators, said van Leeuwen, “the femoral artery is still the dominant access site for complex PCIs, especially for CTOs.”

Sunil Rao, MD (Duke University Medical Center/Durham VA Medical Center, NC), a longtime proponent of radial access who wasn’t involved in the study, said there is a perception that operators might be limited in the types of equipment they can use when performing complex cases via the radial artery.

“There are certain cases where you might want to use a larger-bore guide catheter,” he told TCTMD, highlighting CTOs, left main bifurcations, or places where two stents or larger-bore rotational atherectomy burrs are needed. With CTOs, for example, some of the equipment doesn’t really fit through a 6-Fr system, said Rao.

COLOR, he said, is a clever trial and provides important randomized data. While it’s not a perfect comparison of radial versus femoral access for complex cases—especially since 40% of patients required dual access, which muddies the waters a little bit—the trial suggests a clear win for radial access. 

“It does seem like this is yet another trial that shows there’s an advantage of radial access with respect to safety parameters, that being bleeding and vascular complications,” said Rao. “You’re not sacrificing procedural success, even in these very complex patients where operators want to use a 7-Fr guide. To me, the overall message is that you can do complex cases via the radial approach with current equipment.”

Thinner-Wall Sheath Maintains Inner Diameter 

In the present study, radial operators used a “slender” introducer sheath (Glidesheath; Terumo), a thinner-wall sheath in which the outside diameter is reduced by one French size but the inner diameter is maintained. The technology is designed to maintain an optimal sheath-to-artery ratio and to avoid traumatizing the radial artery; it allows physicians to avoid upsizing to a larger sheath when performing procedures.

Presented at EuroPCR and simultaneously published in JACC: Cardiovascular Interventions, the COLOR study included 388 patients undergoing planned PCI for complex coronary lesions where operators anticipated using 7-Fr guiding catheters. In the cohort, roughly 58% of patients had a CTO, 19% had heavily calcified lesions, 14% were treated for left main CAD, and 9% had bifurcation lesions.

Procedural success was achieved in 86% and 89% of patients randomized to transfemoral and transradial PCI, respectively (P = 0.29). The crossover rate was similar in both study arms, with 2.6% of patients randomized to the femoral access crossing over to the radial approach and 3.6% of transradial patients crossing to femoral access (P = 0.56). A secondary access site was necessary in roughly 40% of patients, mainly for CTOs, but use of dual access did not differ between the two study groups.   

You’re not sacrificing procedural success, even in these very complex patients. Sunil Rao

Regarding the primary endpoint, 19.1% of patients in the transfemoral group had BARC 2, 3, or 5 bleeding or vascular complications requiring intervention at the access site. In contrast, the primary endpoint occurred in just 3.6% of patients treated via the radial artery. With respect to bleeding, the difference between the two approaches was driven by a reduction in BARC 2 events with transradial access. Vascular complications occurred in 0.5% and 4.1% of patients in the transradial and transfemoral groups, respectively (P = 0.04).

There was no significant difference in the risk of major adverse cardiovascular events at 30 days, but the outcomes trended in favor of the transfemoral approach (2.6% versus 6.7% with transradial; P = 0.06). The investigators urge caution with this finding, however, given that the study was underpowered to detect a difference in clinical events.  

To TCTMD, Rao said longtime radial proponents are comfortable using 7-Fr guide catheters with radial access, but the procedures have been made easier with the introduction of larger sheathless guiding catheters as well as the slender sheath technology that allows operators to use 7-Fr equipment. “For people who are early in their radial experience or who might have the perception that you can’t use 7-Fr guiding catheters from the radial approach, I think this paper is really, really valuable,” he stressed.

Convincing ‘Femoral Believers’

To TCTMD, van Leeuwen said those involved in the randomized trial, which included 12 centers, were all experienced with complex cases and noted that the slender introducer sheath allowed operators to use regular guiding catheters. Sheathless systems require another level of expertise and can result in dissections. The slender introducer sheath can be used in nearly all patients, he said.  

In an editorial, Marco Valgimigli, MD, PhD, and Antonio Landi, MD (Cardiocentro Ticino Institute, Lugano, Switzerland), highlight a recent meta-analysis of observational studies on CTO PCI that showed the radial approach was associated with fewer access-site complications and less major bleeding. However, radial access tended to be used in patients with lower baseline risk and less complex coronary lesions. It would be expected that patients at higher baseline risk would derive more benefit from transradial PCI.   

The COLOR trial, they write, shows that radial access is safe even in complex PCI requiring large-bore catheters. They point out that BARC 2 bleeding events remain challenging to adjudicate and that only one-third of patients in the transfemoral arm with BARC 2 bleeding needed a prolonged hospitalization stay.

“Therefore, it remains unclear whether these, most likely minor, events could influence prognosis,” write Valgimigli and Landi.

Like the investigators, they stress that the trend in MACE favoring transfemoral PCI shouldn’t be overemphasized given that COLOR is underpowered for clinical outcomes. However, the numerical imbalance in MACE will likely raise concerns among advocates of transfemoral PCI for complex cases, they acknowledge. “Therefore, further randomized adequately powered trials of radial access versus femoral access in complex intervention are warranted. Only then, will radial access be ready for prime time in complex PCI and become truly persuasive to the ‘femoral believer’ community.”

In terms of the MACE rate, Rao said COLOR is still relatively small and that it would be impossible to make any conclusions about clinical outcomes. As a trialist, he agrees more data would be beneficial but also said it would be a difficult to convince radial-access operators to randomize patients. “That’s the hardest part,” he said. “If you’re someone who has been doing radial access for a long time, you might actually be unwilling to randomize someone to femoral access. That’s the challenge if we’re doing another trial at all in this space. The body of evidence is so clearly in favor of radial access.”