November 8, 2011 (San Francisco, California) — A couple of new studies suggest that the learning curve for transradial-access PCI is steeper than first thought but that if the approach is taught early in training, interventionalists can become proficient accessing the heart via the radial artery.

Presenting data this week at TCT 2011, lead investigator Dr Usman Javed (University of California, Davis) reported that transradial cardiac catheterization, including diagnostic angiograms and coronary interventions, was comparable to the femoral approach when performed by operators in training. In addition, they also observed that procedure times, fluoroscopy times, and contrast utilization were significantly improved after six months of radial-access training.

"The fellows are getting much better at the radial interventions as the year progresses," Javed told heartwire . "One of the major criticisms of the radial intervention is that it takes longer; there are longer fluoroscopy times, and the overall procedure takes longer. For the novice guys, yes, it can sometimes take forever to access the radial artery compared with the experienced ones, and the fluoro time can be longer because people struggle with cannulating coronary arteries. But here we're seeing that different fellows with different skill sets are showing an improvement after six months."

Learning When You're Young

Speaking with heartwire , Javed said UC Davis began doing more and more radial catheterizations 18 months ago. Acknowledging the learning curve involved in transradial interventions, the researchers wanted to assess the safety and feasibility of the transradial cardiac catheterization program when cardiology fellows are the primary operators. Beginning in April 2010, the group collected data on 1777 cardiac catheterizations performed over a one-year period. Of these, 81% were performed via the femoral artery and 19% of cases performed using the radial approach.

Comparing the femoral and radial approaches, investigators report that fluoroscopy times, procedure times, and contrast used during the procedure did not significantly differ between the two procedures. Numerically, there were more major bleeds in the femoral-access intervention arm, but the difference did not reach statistical significance (13 vs 5; p=0.41).

Next, the researchers compared procedural variables among operators who treated patients via the radial artery in the first six months of their fellowship and those who treated patients after six months. Compared with procedures performed within the first six months, fluoroscopy times, procedure times, and contrast used were significantly lower among operators who performed transradial interventions later in the training program.

Procedural Values in Femoral and Radial Interventions

Indices Femoral (n=1438) Radial (n=339) Radial in the first 6 mo (n=163) Radial after 6 mo (n=176) p, femoral vs radial p, radial early vs radial late
PCI (%) 36 27 25 30 0.004 0.25
Fluoroscopy time (min) 18.8 18.5 18.8 14.9 0.38 0.03
Procedure time (min) 69 68 73 63 0.34 0.02
Contrast (mL) 186 167 180 158 0.17 0.03

To heartwire , Javed noted that the study is retrospective and includes all patients undergoing diagnostic catheterizations and interventions. He noted that transradial interventions are more likely to be used in elective cases, and tougher-to-treat patients, such as those with chronic total occlusions, are much more likely to undergo PCI using the femoral artery.

"Overall, the data tell us that radial access is a pretty viable approach, even in training programs, and that the fellows being trained can do as well with it as with the femoral approach," said Javed. "Still, we need to really look a little more deeply at it. Diagnostic catheterizations are probably fine, but what happens with PCI?"

Asked about the learning curve and existing training programs, Javed said that he suspects the early results are likely to be better among physicians trained in the transradial approach in fellowship programs rather than in workshops for practicing clinicians. "I think if training programs started to incorporate the radial approach, this would be better in the long run," said Javed. While the pendulum is shifting a little, most cases are still done via the femoral artery in the US, despite the significantly lower rates of bleeding with radial access.

Steeper Curve

In the second study, which was led by Dr Bharat Gummadi (University of Florida, Jacksonville), researchers showed that the learning curve of transradial interventions among already-practicing cardiologists is a little steeper than previously believed. Three interventional cardiologists with two, five, and 10 years experience in the field, but without any experience using the radial artery, struggled with the radial approach and had fluoroscopy times and contrast volumes that were significantly higher than experienced radial interventionalists.

"The results aren't surprising, but a lot of people were saying that it only takes about 50 cases to become proficient at the transradial approach, but this study shows us that 50 cases is definitely not enough and that 150 cases might not be enough,'' Dr Luis Guzman (University of Jacksonville, Florida), the senior investigator of the study, told heartwire .

For all three operators, fluoroscopy times, one of the more reliable markers of a clinician's level of expertise and proficiency, decreased the more procedures they performed using the radial artery, but no operator, even after 150 procedures, was as proficient as trained radial interventionalists. The experienced operator with 10 years in the field achieved faster proficiency in radial-access interventions, assessed with fluoroscopy times, than the operators with two and five years of experience.

"It turns out that there is a little bit of a learning curve and that the learning curve is a little bit steeper for interventionalists with less experience," Gummadi told heartwire .

Guzman agreed with the sentiments of Javed, noting that fellowship training programs are more hands-on and provide greater guidance to operators. Some of the training courses, he noted, are more didactic in nature, with physicians forced to become proficient at the transradial approach when they return to clinical practice.

Two other studies of transradial vascular access were also presented at the TCT meeting, with one study showing that transradial PCI was not associated with an increased exposure to radiation, while another investigation revealed that the approach was associated with increased preparation time, although the increase, less than two minutes, does not appear to be clinically meaningful.

Guzman reports consulting for AstraZeneca and Merit Medical. Javed and Gummadi report no conflicts of interest.


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