ISAR-CABG: DES superior to BMS in saphenous vein graft lesions

American College of Cardiology 60th Annual Scientific Sessions

NEW ORLEANS — In what researchers called the largest randomized, multicenter trial comparing stents in saphenous vein graft lesions, drug-eluting stents were found to led to a lower composite rate of death, MI and repeat revascularization.

“Usually, all randomized trials comparing drug-eluting stents [DES] and bare-metal stents [BMS] have excluded lesions located in the saphenous vein grafts,” Julinda Mehilli, MD, director, clinical research and data coordinating, Intracoronary Stenting and Antithrombosis Research (ISAR) Center, German Heart Center, Munich, and study investigator, said in a press conference, later adding that the two trials comparing both stents in this indication included only 160 patients and produced incomplete results. “Thus the aim of the ISAR-CABG study was to have a study adequately powered for clinical endpoints to compare DES and BMS.”

The German researchers of the ISAR-CABG trial enrolled 610 patients who had undergone CABG and had ischemic symptoms or evidence of myocardial ischemia in the presence of at least 50% de novo stenosis in saphenous vein grafts. The patients were then randomly assigned to receive either drug-eluting (DES; n=303; mean age, 71.4 years) or bare metal (BMS; n=307; mean age, 71.5 years) stents. DES used in the study included the sirolimus-eluting (Cypher, Cordis), biodegradable polymer sirolimus-eluting and paclitaxel-eluting (Taxus, Boston Scientific) stents.

The study’s primary endpoint was defined as the composite of major adverse cardiac events (MACE) including death, MI and target lesion revascularization (TLR) at 1-year, while the secondary endpoints were individual rates of death, MI, ARC [Academic Research Consortium]-definite thrombosis and the need for TLR over one year.

Early data at 30 days indicated MACE rates of 5.9% in the BMS arm vs. 2.6% in the DES (P=.05). Similarly, researchers found that the primary endpoint occurred more frequently in the BMS group compared with the DES (22.1% vs. 15.4%; P=.03). The only secondary endpoint to differ to a statistically significant extent was TLR, which favored the DES group (7.2% vs. 13.1%; P=.02).

Following the conference, Mehilli spoke with Cardiology Today and explained that prior to these findings people were afraid of DES because the risk of more and longer stent thrombosis compared with BMS, not to mention the high risk of occlusion at long-term with saphenous vein grafts.

“This randomized controlled trial, the first with such a large number of patients powered for clinical endpoints, gives a definite answer: DES are safe. They don’t increase mortality, MI or stent thrombosis rate, and instead reduce the revascularization rate in bypass lesions,” she said. - by Brian Ellis

For more information:

Mehilli J. LBCT III, Session 3014. Presented at: ACC 60th Annual Scientific Sessions; April 2-5, 2011; New Orleans.

The reason trials like this are important is because the interventional community has been criticized for putting in DES off-label. Be that as it may, there are some safety concerns about that practice and those concerns seem to have been supported by the R-RISK trial which showed that patients who had drug-coated stents as opposed to uncoated seemed to have higher mortality. That was a small trial and I think it was largely driven by the fact that the patients who had the non-coated stents placed had a 0% observed mortality which is somewhat implausible. Patients who’ve had bypass surgery before develop new blockages. Those patients tend not to be immortal to say the least. So I think that is an example of a type-1 statistical error.

That’s why we needed to do a larger, more adequately powered trial. To the credit of this ISAR group, this is a very helpful trial showing that these devices seem to be both safe and efficacious in this “off-label” indication.

– Edward J. McNulty, MD
Cardiac Surgeon, The Permanente Medical Group, San Francisco

Disclosure: Dr. Mehilli reports receiving lecture fees from Abbott. Dr. McNulty reports norelevant financial disclosures.

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