RAPS: Radial Arteries Superior to Saphenous Vein Grafts at 5 Years After CABG

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NEW ORLEANS, LA—At 5 years after treatment, coronary artery bypass graft (CABG) surgeries performed using the radial artery offer superior patency compared with those using the saphenous vein, according to late-breaking clinical trial results presented April 4, 2011, at the annual American College of Cardiology Scientific Session/i2 Summit.

For the Randomized Multicenter Radial Artery Patency Study (RAPS), Stephen E. Fremes, MD, MSc, of Sunnybrook Health Sciences Centre (Toronto, Canada), and colleagues enrolled 561 patients undergoing CABG for 3-vessel disease at 13 Canadian centers. Randomization was performed within individual patients, such that the right coronary artery and left circumflex artery each were assigned to receive treatment with radial artery or saphenous vein grafts. Therefore, every patient received both of the 2 study grafts.

Complete graft occlusion was defined as TIMI flow grade 0 with no opacification of the distal vessel, and functional graft occlusion was defined as TIMI flow grade 0, 1, or 2.

Comparing Conduits

Among 440 patients available for 1-year follow-up, previously published results showed that the use of radial arteries reduced the prevalence of complete graft occlusion compared with saphenous veins (8.2% vs. 13.6%; P = 0.009), while the 2 approaches offered similar levels of functional graft occlusion (12.3% and 14.3%, respectively; P = 0.37).

At 5-year follow-up, an intention-to-treat analysis in 269 patients showed that functional and complete graft occlusion both were markedly improved with radial artery vs. saphenous vein grafts (table 1).

Table 1. Angiographic Outcomes at 5 Years

Moreover, radial arteries tended to have less graft disease. Among the 164 patients who had both grafts patent, stenosis greater than 25% was observed at similar levels for both graft types in the proximal and distal anastomoses, but graft body lesions were less common with radial arteries than with saphenous veins (6.7% vs. 15.2%; P = 0.02). Consequently, radial grafts were less likely to be either stenotic or completely occluded than saphenous vein grafts (21.9% vs. 33.8%; P = 0.004).

Target vessel stenosis was a risk factor for graft occlusion. Vessels with at least 90% stenosis at baseline were less likely to fail than those with 70 to 89% occlusion, regardless of which study graft they received. Radial arteries produced particularly low rates of functional (8.8%) and complete occlusion (6.3%) when used for target vessels with more severe proximal stenosis.

In terms of clinical outcomes, the rates of MACE (defined as any death, nonfatal MI, repeat CABG, or PCI) were 10.5% within 30 days, 1.2% between 31 days and 1 year, and 14.9% after 1 year. Overall survival was 96% at 5 years, 91% at 7.5 years, and 82% at 10 years. However, because the study design limits the ability to determine the clinical consequences of each graft type, such results should be considered descriptive rather than explanatory, cautioned Dr. Fremes, who added that the patient population also tended to be relatively young and low risk.

Findings Spark Panel Discussion

Session co-chair Edward J. McNulty, MD, of the Kaiser Permanente Medical Group (San Francisco, CA), commented, “This is a poignant illustration of the importance of long-term follow-up in these studies. If you had made practice changes based on the 1-year outcomes, obviously you would have missed the potential [benefits] of radial conduits on late patency as well as on clinical events.”

The findings are the latest chapter in what has amounted to a search for a holy grail, noted James B. McClurken, MD, of Doylestown Hospital (Philadelphia, PA).

Bilateral use of the internal mammary artery has not been widely adopted, partly because of concerns about healing and infection in certain subgroups, but the research on the approach has “clearly shown that arterial revascularization is best,” he said, noting that the radial artery does not perform quite as well as the internal mammary artery but is better than vein grafts. “I think the radial artery is a great conduit. I use it frequently, and I use it frequently with the [internal mammary artery].”

RAPS comes with some caveats, Dr. McClurken added. “It’s important to place [radial artery grafts in] highly obstructed vessels, so that there’s not competitive flow and to maintain patency for the longest period of time,” he said.

Co-chair Gregg W. Stone, MD, of Columbia University Medical Center (New York, NY), however, questioned whether the surgical community has fully embraced arterial revascularization and asked if the current findings will encourage further use.

Steven F. Bolling, MD, of the University of Michigan Health System (Ann Arbor, MI), predicted RAPS will have an impact. “Obviously, it’s a cultural change for us, just like 25 years ago it took us awhile to switch over to using the mammary, because technically it’s slightly more difficult than using the saphenous vein,” he said, but the new findings lend strong support to an all-arterial revascularization strategy.

By the time a 5-year study is able to report its outcomes, techniques and technologies have improved so much that the findings can be outdated, Dr. Stone pointed out, asking, “What do we do about that?”

Bernard J. Gersh, MB, ChB, of the Mayo Clinic (Rochester, MN), joked, “At least it’s not worse.”

“Any trial [that takes 3 to 5 years] is obsolete, by and large, by the time it’s completed,” he acknowledged. “And that’s just a fact of life. There’s nothing we can do about that [apart from considering the results in context]. It’s an imperfect world.”

 

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Source:
Fremes SE. Radial artery and saphenous vein patency more than 5 years following coronary artery bypass surgery: Results from the randomized multicenter Radial Artery Patency Study (RAPS). Presented at: American College of Cardiology Annual Scientific Session/i2 Summit; April 4, 2011; New Orleans, LA.

 

 

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