Campeau Paradox: Is Femoral Proficiency Lost When Radial Access Thrives?

Increasing utilization of radial access may have the unintended effect of leading to more vascular complications for femoral access due to a loss of experience among operators, researchers say in a new paper. The authors name their finding the ‘Campeau Paradox,’ in honor of the Canadian transradial pioneer, Lucien Campeau. 

Another View: Campeau Paradox: Is Femoral Proficiency Lost When Radial Access Thrives?

The study findings were published online November 18, 2015, in JACC: Cardiovascular Interventions.

“We speculate that the radial paradox stems from [the] operator’s reduced expertise in safely accessing the femoral artery,” write Lorenzo Azzalini, MD, PhD, MSc, of the University of Montreal (Québec, Canada), and colleagues. “We further speculate that modern radial operators reserve [femoral access] for complex PCIs in critical clinical scenarios. The situation becomes synergistically problematic when poorly trained operators attempt challenging [femoral procedures].”

To examine the influence of access route on vascular complications in consecutive patients referred for either diagnostic or therapeutic cardiac catheterization, the researchers looked at a historical cohort (1996-1998; n = 6,922) in which only femoral access was performed, and a contemporary cohort (2006-2008; n = 10,137) in which both radial and femoral were used equally.

Compared with the historical cohort, those in the contemporary cohort were older and presented a higher burden of cardiovascular risk factors and comorbid conditions, while more patients in the historical cohort underwent therapeutic vs diagnostic catheterizations.  

More Femoral Complications Now Than Before

On logistic regression analysis, the risk of vascular access site complications was higher in the contemporary cohort (OR 1.48; 95% CI 1.17 to 1.89). Within the more recent cohort, fewer complications were seen with radial than with femoral access (1.44% vs 4.19%; P < .001).

Additionally, contemporary femoral access patients had more vascular complications than did those who had femoral access in the historical cohort, a difference driven by higher rates of major hematoma, and retroperitoneal hematoma.

Complication Rates for Femoral-Access Patients.

This finding remained consistent when diagnostic and therapeutic catheterizations were analyzed separately (P = .002 and P < .001, respectively).

Azzalini and colleagues say if radial access is indeed linked to an increase in femoral vascular complications, “eliminating” radial access would potentially avoid up to 52.7% of vascular access site complications in femoral patients.

Educational programs for trainees and young interventional cardiologists should take this paradox into consideration and maximize exposure to optimal femoral access technique, they add. “Such programs could include formal teaching, focused workshops and simulators, as is currently done for [radial access]. Finally, maintaining a minimal [femoral access] volume could also be recommended.”

Advice Goes Against Published Literature

In an editorial accompanying the study, Sunil V. Rao, MD, of Duke Clinical Research Institute (Durham, NC), and James Nolan, MD, of University Hospital of North Staffordshire (Stoke-on-Trent, United Kingdom), concede that addressing the issue of “maintaining proficiency with vascular access in an environment of rapid change,” is important.

That being said, the study authors’ assertion that femoral complications could be avoided by eliminating radial procedures “not only goes against much of the published literature, both randomized and observational, showing overwhelmingly that radial approach is superior to femoral approach in preventing vascular complications, but also represents causality language that is not exactly supported by their observational study,” they assert.

Similarly, Robert W. Yeh, MD, MBA, of Beth Israel Deaconess Medical Center (Boston, MA), told TCTMD in an email that many things about the practice of PCI changed from the first time period the study authors examined to the second time period, yet they attribute differences in rates of vascular complications between these 2 periods entirely to the uptake of radial artery catheterization.

“While the results are provocative, the data are not sufficient to support the cause-effect relationship that the authors are hypothesizing,” he noted.

Yeh applauded the authors for raising the general issue that femoral experience is important for trainees even in a radial-predominant era, but he emphasized that both strategies are necessary to deal with the diversity of patients seen in practice.

 “I consider myself a radial-first operator, but there are still times, particularly in complex chronic occlusions, for example, that I still start with a femoral approach that I think gives me the opportunity to achieve success more quickly,” Yeh said. “But large bore sheathless guides that can be used from the radial approach may soon close this gap.”

Operator-Level Data Needed

In a telephone interview with TCTMD, Ian C. Gilchrist, MD, of Hershey Medical Center (Hershey, PA), said the issue of decreased femoral expertise has been a concern with rising rates of radial access being reported, but he said the study fails to demonstrate that this is a widespread problem as opposed to possibly an operator-level problem at some centers.

“They say that their overall institutional rate of radial and femoral procedures is 50/50,” Gilchrist said. “It is highly unlikely that all of their operators are doing half femoral, half radial all the time. There very well may be some who are doing 95% radial and others who are doing almost no radial. The complication rates are going to be different for those operators, so adjusting the data by operator would be important if you are really going to look properly at this issue.”

According to Rao and Nolan, recent findings suggest that any advantage of radial over femoral may not be manifest unless the proportion of transradial procedures is 80% or greater. They also note that patients in the study who were selected for femoral access had more comorbidities than those selected for radial access and a higher incidence of risk factors for major vascular complications. Furthermore, 31.1% of femoral patients received a vascular closure device.

“Therefore, it appears that the risk-treatment paradox, rather than a ‘radial paradox,’ was present in this study,” they conclude.

Gilchrist added that even in radial training courses, the emphasis is rarely on exclusively doing radial. “The appropriate emphasis should be on the right access at the right time for the right procedure,” he said.   

1. Azzalini L, Tosin K, Chabot-Blanchet M, et al. The benefits conferred by radial access for cardiac catheterization are offset by a paradoxical increase in the rate of vascular access site complications with femoral access: the Campeau radial paradox. J Am Coll Cardiol Inv. 2015;Epub ahead of print.
2. Rao SV, Nolan J. Proficiency with vascular access: don’t rob Peter to pay Paul [editorial]. J Am Coll Cardiol Inv. 2015;Epub ahead of print. 


  • Drs. Azzalini, Nolan, and Gilchrist report no relevant conflicts of interest. 
  • Dr. Rao reports serving as a consultant for Medtronic and Terumo Interventional Systems. 
  • Dr. Yeh reports serving on the advisory board of Abbott Vascular, and as a proctor for CTO intervention for Abbott Vascular and Boston Scientific. 

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