乌鸦传媒

NEW ORLEANS -- Stenting appears equal to coronary artery bypass (CABG) surgery for left main coronary artery disease, Korean researchers found.

Sirolimus-eluting Cypher stents were noninferior to CABG for composite major adverse cardiac and cerebrovascular events at one year (8.7% versus 6.7%, P=0.01 for noninferiority), Seung-Jung Park, MD, PhD, of Asan Medical Center and the University of Ulsan in Seoul, South Korea, and colleagues reported here at the American College of Cardiology meeting.

The two treatments remained even at two years for this primary endpoint incorporating all-cause mortality, myocardial infarction, stroke, and target-vessel revascularization (12.2% versus 8.1%, HR 1.50, P=0.12), according to results released simultaneously online in the New England Journal of Medicine.

But the study's wide confidence intervals for noninferiority meant that "the results cannot be considered clinically directive," Park's group warned in the paper.

Yet it still should prove helpful by broadening the evidence base from the SYNTAX trial, commented Sidney Smith, MD, of the University of North Carolina at Chapel Hill and a past president of the American Heart Association.

"It opens the door to use of stenting but doesn't give stents a leg up," he told 乌鸦传媒.

SYNTAX had shown an advantage to CABG compared with the paclitaxel-eluting Taxus Express stent that continued to grow over three years of follow-up in a population with typically more complex lesions.

But that landmark trial hinted at a niche for stenting in left main disease, with three-year major cardiovascular or cerebrovascular event rates favoring stenting in the low-risk group (18.0% versus 23.0%, P=NS) and equivalent for intermediate-risk patients (P=0.90) and with a trend for lower risk of death in the intermediate-risk stenting group (4.9% versus 12.4%, P=0.06).

Some experts had cautioned that these subgroup results could be just chance findings, but European guidelines were swayed in favor of stenting for left main disease.

"We're seeing liberalization of the use of left main stenting in the U.S." as well, Smith said in an interview.

In an attempt to settle the issue, PRECOMBAT randomized 600 patients with unprotected left main coronary artery stenosis to CABG or sirolimus-eluting stents in an open-label manner.

Baseline angiographic characteristics and procedural success in revascularization were similar between groups. Only 6.0% of the stent group and 8.0% of the CABG group were considered at high operative risk. But follow-up angiography at eight to 10 months was more common in the stenting group (75.3% versus 24.7%, P<0.001).

Over the median 24 months of follow-up, no significant differences emerged for individual components of the primary endpoint at one year: death from any cause, myocardial infarction, stroke, or ischemia-driven target-vessel revascularization.

An as-treated analysis also showed no difference in the rate of these events cumulatively at 12 months (P=0.04 for noninferiority).

Extending the follow-up to 24 months likewise yielded no differences in any of the individual components of the primary major adverse cardiac and cerebrovascular event composite, except for target vessel revascularization, which was more common with stenting than surgery (9.0% versus 4.2%, hazard ratio 2.18, P=0.02).

Stent thrombosis occurred in less than 1% of patients at 24 months.

A registry of the 845 left main stenosis patients not eligible for randomization repeated the results in the randomized cohort, without significant differences in outcomes between those who got stenting and those who got CABG, with the exception of more ischemia-driven target-vessel revascularization.

The researchers noted that the PRECOMBAT event rates were lower than seen in other trials, such as SYNTAX, perhaps because of less complex disease or differences in devices and techniques or the racial or ethnic propensity for ischemic or thrombotic complications.

"Our extensive use of intravascular ultrasonography, single stents in bifurcation lesions, off-pump surgery, and internal thoracic artery for grafting onto the left anterior descending artery may have improved the outcomes reported here," they wrote in the paper.

Smith called the results impressive, noting that it appeared that the trial included lesions in the more difficult distal left main.

But the group cautioned that the unexpectedly low event rates made the study underpowered.

"In fact, the noninferiority margin of 7 percentage points was almost equivalent to a 100% increase in the observed event rate of the primary endpoint in the CABG group at one year," they added.

Other limitations were the relatively high incidence of crossover from stenting to CABG, which could have biased the results toward the null; the systematic angiography done in the stent but not CABG group; and the possibility that two years' follow-up may not have been long enough to show a difference, Park's group suggested.