ISAR-CABG Published: DES Preferred for Saphenous Vein Graft Lesions

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In the largest randomized trial to date comparing drug-eluting stents (DES) and bare-metal stents (BMS) in saphenous vein graft (SVG) lesions, DES produced lower rates of restenosis and target lesion revascularization (TLR), making them the preferred treatment in this high-risk group. Results of the ISAR-CABG trial were published online August 28, 2011, ahead of print in the Lancet.

The trial results were initially presented April 4, 2011, at the annual American College of Cardiology Scientific Session/i2 Summit in New Orleans, LA.

For ISAR-CABG (Is drug-eluting Stenting Associated with improved Results in Coronary Artery Bypass Grafts?), researchers led by Julinda Mehilli, MD, of Deutsches Herzzentrum (Munich, Germany), randomized 610 patients with de novo SVG lesions to treatment with DES (n = 303) or BMS (n = 307) at 4 German centers between November 2007 and February 2010. DES used in the study included sirolimus-eluting stents (permanent- and bioabsorbable-polymer) and paclitaxel-eluting stents.

At 30 days, the primary composite of death, MI, and TLR was more than halved with DES (2.6% vs. 5.9%). By 1 year, DES had achieved a relative reduction of 36%, primarily due to a lower TLR rate. TVR was also reduced, while rates of death, MI, and definite/probable stent thrombosis were each similar between groups (table 1).

Table 1. ISAR-CABG: 1-Year Clinical Results

 

DES
(n = 303)

BMS
(n = 307)

P Value

Death/MI/TLR

15.0%

22.1%

0.02

Death

5.1%

4.7%

0.83

MI

4.1%

6.0%

0.27

Ischemia-Driven TLR

6.8%

13.1%

0.01

Ischemia-Driven TVR

9.6%

15.5%

0.01

Definite/Probable Stent Thrombosis

0.7%

0.7%

0.99


These results were maintained across multiple subgroups defined according to age (above or below 73.2 years), sex, diabetes status, SVG age (above or below 13 years), or SVG degeneration score (above or below 1). There were also no differences within the DES group according to stent type.

On follow-up angiography at a median of 6.7 months (performed in 72% of the patients), binary restenosis was almost halved in the DES group compared with the BMS group (15% vs. 29%; P < 0.0001). In addition, occluded target SVGs were identified in 6% of DES patients vs. 12% of BMS patients (P = 0.008).

The authors attributed the positive outcomes with DES entirely to the devices’ increased antirestenotic efficacy, concluding that “[i]n patients undergoing percutaneous coronary intervention for de-novo saphenous vein graft lesions, drug-eluting stents are the preferred treatment option because they reduce the risk of adverse events compared with bare-metal stents.”

Broader Indication Urged for DES

While longer-term data are still needed, the current results “suggest that drug-eluting stents might be as useful for treatment of saphenous vein graft failures as they are for lesions of native coronary vessels,” they write, adding that ISAR-CABG even supports “further broadening of the indication for the use of drug-eluting stents” in patients with CAD to include patients with SVG lesions.

In an accompanying editorial, David P. Taggart, MD, PhD, of the University of Oxford (Oxford, United Kingdom), and Adrian P. Banning, MD, of John Radcliffe Hospital (Oxford, United Kingdom), agree that DES significantly reduce ischemia and restenosis, calling the results of ISAR-CABG “reassuring.” However, they point out the 15% angiographic restenosis rate as emblematic of the “challenge of treatment of degenerative saphenous vein grafts,” and observe that the reduction in restenosis had no effect on survival or MI.

In fact, the editorial adds, mortality was still 5% at 1 year, “mandating a continued evolution of interventional techniques based on drug-eluting stents or medical treatment, or both, for this challenging, biologically distinct clinical entity.”

A Strong Answer

Nevertheless, Emmanouil S. Brilakis, MD, PhD, of the University of Texas Southwestern Medical Center at Dallas (Dallas, TX), commented to TCTMD in a telephone interview: “This is the biggest trial in the field, and [it] provides a very strong answer.”

He explained that while the angiographic restenosis rate was 15% with DES, the TLR rate was still 6.8%. “Many of those binary restenoses were not treated with repeat stent implantation,” Dr. Brilakis said. Regarding mortality, he reported that an annual rate of 5% is expected in patients with vein graft stents. Also, “many deaths are due to noncardiac causes, which stenting is not going to affect no matter what we do,” Dr. Brilakis pointed out. “There is no explanation in the study as to how much was cardiac vs. noncardiac mortality.”

He added that the trial’s angiographic follow-up represents a limitation because of the potential for the oculostenotic reflex. “What we want to see is a study with purely clinical follow-up,” Dr. Brilakis said. “That would give a more definitive answer.”

He went even further than the study authors regarding use of DES in native vs. non-native coronary vessels. “People are using DES in the majority of interventions in the United States, but it’s about 10% less in vein grafts than in natives, maybe 75% and 65%,” he said. “I think after these data, people may be a little more willing to increase DES use in vein grafts, but in my opinion, vein grafts have a higher restenosis risk than natives, so if anything, vein grafts should have more DES use than native coronaries.”

Dr. Brilakis noted that there are 2 upcoming multicenter trials, one in Europe and one in the United States, which will further compare DES and BMS in SVG lesions. He is the principal investigator of the US trial, which will feature only clinical follow-up and will mandate distal embolic protection when possible. Use of distal embolic protection in ISAR-CABG was under 5%.

Study Details

After intervention, all patients were prescribed 200 mg/day aspirin indefinitely, clopidogrel 150 mg for the first 3 days (or until discharge), followed by 75 mg/day for at least 6 months.

 


Sources:
1. Mehilli J, Pache J, Abdel-Wahab M, et al. Drug-eluting versus bare-metal stents in saphenous vein graft lesions (ISAR-CABG): A randomised controlled superiority trial. Lancet. 2011;Epub ahead of print.

2. Taggart DP, Banning AP. Stents and failing vein grafts: Are we any wiser after ISAR? Lancet. 2011;Epub ahead of print.

 

Disclosures:

  • The study was funded by Deutsches Herzzentrum.
  • Dr. Mehilli reports receiving honoraria from Abbott and Terumo.
  • Drs. Taggart and Banning report no relevant conflicts of interest.
  • Dr. Brilakis reports serving as the principal investigator of the upcoming DIVA (Drug eluting stents In saphenous Vein graft Angioplasty) trial and the completed SOS (Stenting Of Saphenous vein grafts) trial, serving on the speaker’s bureau for St. Jude Medical, and receiving research grants from Abbott Vascular.

 

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