STS: Advantage of Stents Over CABG Fizzles in 'Real World'

SAN DIEGO, Jan. 30 -- Real-world revascularization outcomes pan out better with coronary artery bypass graft (CABG) than with percutaneous coronary intervention (PCI), even when drug-eluting stents are used.

So found Michael Mack, M.D., of the Cardiopulmonary Research Science and Technology Institute in Dallas, and colleagues, in the 4,300-patient Coronary Artery Revascularization (CARE) study. The results of the observational study were presented at the Society of Thoracic Surgeons meeting here.

The researchers found that stents resulted in an 8.5% higher rate of major cardiac adverse events after 18 months than bypass surgery and double the rate of repeat revascularizations. Event-free survival rates were significantly improved with bypass surgery as well.

The researchers prospectively examined outcomes in all 4,336 patients undergoing isolated coronary revascularization in eight community hospitals over six months in 2004. Patients were followed for 18 months by direct contact or, failing that, by the Social Security Death Index.

Most of the patients underwent PCI (71.2%) rather than CABG. Most of these PCI procedures used drug-eluting stents (72.8%) rather than bare-metal stents. Among the 28.8% of revascularizations done as CABG surgery, 52.2% were off-pump and 47.8% were on-pump.

At the 18 month follow-up, the mortality findings were:

• No significant difference between on- and off-pump CABG (6.6% versus 8.7%, P=0.17),
• A trend toward higher mortality for bare-metal stents versus drug-eluting stents (10.2% versus 7.8%, P=0.11), and
• No significant difference for PCI versus CABG (8.5% versus 7.6%, P=0.35).

Event-free survival at 18 months was significantly more common among patients treated with CABG than PCI (P=0.002), and the survival curves showed evidence of diverging with longer follow-up.

Dr. Mack cautioned that "the study was underpowered to show a difference in mortality. To do so would require a significantly larger study in the range of 80,000 patients", he said.

Nevertheless, he said, any discussion about bypass surgery going away is clearly hyperbole. Indeed, he added, CABG might need to be used more frequently in complex patients.

Coronary revascularization shifted significantly from CABG to PCI over the past two decades on the basis of evidence from randomized controlled trials that enrolled only 4% of screened patients and may have doubtful applicability to the broader population seen by most surgeons, he said.

For major adverse cardiac events in the CARE study, the 18-month findings were:

• No significant difference between on- and off-pump CABG (14.5% versus 14.9%, P=0.82),
• A significant advantage for drug-eluting stents compared with bare metal stents (20.9% versus 26.8%, P=0.008), and
• A highly significant difference favoring CABG versus PCI (14.7% versus 23.2%, P

Dr. Mack said the difference between trials and the registry was mostly due to use in patients with multi-vessel disease and off label use. "Those patients probably would have been better served by bypass surgery," he said.

Session moderator John R. Doty, M.D., of the LDS Hospital in Salt Lake City agreed.

"Drug-eluting stents aren't that much of an advance," he said. "They aren't better than surgery despite the hype."

However, Dr. Mack said that the findings do support off-pump surgery.

"Practitioners are making the right decisions right now for the right reasons," he said. "I think in terms of surgeons they can be comfortable that off-pump surgery does not lead to graft closure and problems later on and that off-pump surgery is just as good as on pump surgery in terms of the major results clinically."