NEW ORLEANS – Drug-eluting stents outperformed bare-metal stents when placed in saphenous vein graft lesions that developed post-coronary artery bypass graft, according to the largest study ever performed to compare these two types of stents in this setting.

Specifically, drug-eluting stents (DES) significantly reduced the rate for the combined primary end point of death, myocardial infarction, and repeat revascularization procedures in the ISAR (Intracoronary Stenting and Antithrombotic Regimen) –CABG trial, presented at the annual meeting of the American College of Cardiology on April 4.

"This study shows us that we don’t have to be afraid of DES in patients with these high-risk lesions, because use of DES cuts down the need for target vessel revascularization by 50% and does not increase myocardial infarction mortality and stent thrombosis formation when compared with BMS [bare-metal stents]," said Dr. Julinda Mehilli, director of clinical research and data coordinating ISAR at the German Heart Center in Munich.

DES have been shown to be more effective and as safe as BMS in native coronary artery lesions. Saphenous vein grafts are used extensively in CABG surgery, but in a high percentage of patients, these grafts are vulnerable to atherosclerosis and subsequent restenosis. The options for re-opening the vein graft include angioplasty with a stent and a second CABG, which carries higher mortality and morbidity risks than the first CABG.

Only two small studies have compared DES versus BMS in saphenous vein graft lesions, and they had conflicting results. The larger ISAR-CABG is powered for clinical events.

ISAR-CABG enrolled 610 patients who underwent a first CABG with a saphenous vein graft and developed at least one stenotic lesion of at least 50% in the graft. Patients were randomized to receive either a DES or a BMS in a 1:1 ratio. In the DES group, patients were assigned 1:1:1 to three commonly used types of drug-eluting stents (Cypher, Taxus, and BP Sirolimus) to mirror real-world use, Dr. Mehilli explained.

The primary end point was a composite of death, myocardial infarction, and target-vessel revascularization at 1 year of follow-up post percutaneous coronary intervention (PCI) for stent placement. Secondary end points were each of those events separately, as well as ARC (Academic Research Consortium)-definite stent thrombosis.

Both groups had comparable characteristics at baseline. Mean age was about 71.5 years; about 15% were female, about 72% had hypertension, about 36% had diabetes, about 7% were current smokers, about 87% had hyperlipidemia, the saphenous vein graft was about 13.5 years old, and about 55% had a previous history of myocardial infarction. Also, disease characteristics were similar between the two groups. About 50% of patients had diffuse disease. More than 60% had unstable angina, and 99% had multivessel disease. Lesions were evenly distributed in the saphenous vein graft. The degeneration score for saphenous vein grafts and the distribution of lesions within the graft were similar between groups, with about 40% of patients having moderate or severely degenerative grafts. TIMI flow rates pre- and post-PCI were similar between the two groups as well.

At 1 year, DES reduced the risk of the primary end point by 35%, compared with BMS, with rates of 15.4% and 22.1%, respectively, a significant difference. The reduction in the DES group was driven primarily by a significant 52% reduction in target vessel revascularizations, which occurred in 7.2% of the DES patients, compared with 13.1% of the BMS recipients.

Both types of stent were comparable in safety, with a similar rate of stent thrombosis, death, or myocardial infarction, said Dr. Mehilli. The rates of all-cause death or myocardial infarction were similar between the two groups, at 8.5% and 10.9% of patients in the DES and BMS groups, respectively. One patient and zero patients, respectively, experienced ARC-definite stent thrombosis.

"Although saphenous vein graft lesions remain a challenging disease subset for angioplasty, this study demonstrates that DES can be safely used to reduce adverse events in this high-risk subset of patients," Dr. Mehilli said.

Dr. Steven R. Bailey commented that, "This study was designed to answer appropriate questions." However, "It is surprising that there were so few females," added Dr. Bailey of the University of Texas Health Sciences Center, San Antonio.

He asked Dr. Mehilli if drug-eluting stents were compared with bare metal stents in subsets related to the complexity of saphenous vein graft lesions. She replied that a subgroup analysis of ISAR-CABG will be forthcoming.

Dr. Mehilli said that, in Germany, the overwhelming number of stents used in saphenous vein graft lesions are DES, and that the current study supports this practice.

The study was funded by the German Heart Center in Munich and by Cordis. Dr. Mehilli disclosed lecture fees from Abbott. Dr. Bailey has received consulting fees/honoraria from Volcano Corp.

Drug-Eluting Stents Superior to Bare Metal Stents in Certain Patients Following CABG