番茄社区

MUNICH – After 10 years of follow-up, outcomes were better in patients receiving two arterial grafts in performing coronary artery bypass graft surgery (CABG) than in those receiving a combination of artery and veins, a researcher said here.

But because many participants were treated off-protocol in the so-called Arterial Revascularization Trial (ART), the definitive answer remains in doubt.

In the primary endpoint of the study (10-year mortality), 329 CABG patients who were treated randomized to the single arterial graft died during the study period compared with 315 patients who died who were originally assigned to receive two arterial grafts (HR 0.96, 95% CI 0.82-1.12), reported David Taggart, MD, PhD, of the University of Oxford in the United Kingdom.

There was also no significant difference between groups for the composite of death, myocardial infarct, or stroke at 10 years.

However, Taggart said in his presentation at the annual meeting of the European Society of Cardiology, the results were confounded because more than one-third of patients received a treatment opposite to the one assigned.

In the end, 14% of patients randomized to receive two thoracic (mammary) arteries actually received just one artery graft, and 22% of the patients assigned to receive a single arterial graft actually got two – most often the thoracic artery plus a radial artery. He said the crossovers tilted the balance towards the single artery group in the intention-to-treat analysis. The use of the radial artery has proven to remain patent substantially longer than do vein grafts, Taggart said.

In his as-treated exploratory analysis, patients who received any two arterial grafts appeared to have a lower mortality (HR 0.81, 95% CI 0.68-0.95) and a lower composite of death, MI, or stroke (HR 0.80, 95% CI 0.69-0.93) compared to those who received a single arterial graft.

Although these findings are relevant, they are not a randomized comparison and require confirmation in future trials, Taggart suggested.

He also said the trial's results may have also been skewed because some surgeons involved in the trial did not have the expertise required to perform the dual thoracic artery CABG procedure. "Surgeons tend to exaggerate their experience," he said.

Among surgeons who had completed fewer than 50 operations before entering the trial, the mortality and composite outcomes were not significantly different between the single and double graft arms. But among surgeons completing more than 50 procedures, outcomes were significantly in favor of the dual artery treatment. He noted that one surgeon – who completed 416 procedures in the trial – had a crossover rate of less than 1%.

"I think that if everyone had done the procedure to the same extent as this surgeon then we would have had a very substantial positive result," Taggart said. "Surgeon experience appears to be a crucial factor for outcomes with bilateral internal thoracic grafts," he said.

The trial enrolled patients from June 2004 through December 2007 from 28 cardiac surgery centers in the United Kingdom, Poland, Australia, Brazil, India, Italy and Austria. The researchers randomized 3,102 patients – 1,554 to a single thoracic artery and 1,548 to a double thoracic artery procedure. Taggart said the patients were well-treated medically with 89% on statins, 81% on aspirin, 73% on angiotensin inhibitors and 74% on beta blockers.

"It seems obvious from this trial that the outcome depends very much on the surgeon," said Steen Kristensen, MD, DMSc, of Aarhus University Hospital, Skejby, Denmark, moderator of a press conference at which Taggart presented his paper.

"If I was going to have my coronaries fixed, it would be by a good surgeon and with both of the thoracic arteries used," he told 番茄社区.

But Kristensen questioned whether the use of both thoracic arteries would be a good choice in a patient with diabetes or other diseases leaving them prone to infection.

Indeed, Taggart said there were populations that would not be candidates for the dual artery surgery. "I would avoid using dual artery CABG in patients who are severely obese, or who have diabetes. These patients have a higher risk of internal infection. But if you take the 80% of patients who are not morbidly obese, without diabetes, you can harvest these arteries without problems."

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