Chicago, IL - There is no significant difference in major outcomes between stenting and CABG in patients with left main coronary artery disease, according to the results of the Revascularization for Unprotected Left Main Coronary Artery Stenosis: Comparison of Percutaneous Coronary Angioplasty vs Surgical Revascularization (MAIN-COMPARE) registry study [1]. The findings were reported by Dr Seung-Jung Park (Asan Medical Center, Seoul, Korea) during a late-breaking session at the American College of Cardiology Scientific Sessions/i2 Summit-SCAI Annual Meeting and published online March 31, 2008 in the New England Journal of Medicine.

Dr Seung-Jung Park

Conference attendees hailed the findings, which challenge the often-prevailing view that surgery is usually the best option for left main coronary artery disease, a condition that has the worst prognosis of any form of CAD. The only major difference between the stent and surgery groups was a higher rate of target vessel revascularization (TVR) in the stent group.

Dr David Holmes (Mayo Clinic, Rochester MN) gave a rousing discussion of the large observational study, in which he applauded Park—whom he affectionately called "SJ"—on a "tremendous" trial. Holmes lamented the US practice that he says is guided by the mantra: "Thou shalt operate on those with left main disease" and then proceeded to rip to shreds the foundations upon which this is based—a "landmark" VA trial, published in 1972, based on just 91 patients. "These are the data that our guidelines came from, upon which we have changed practice—the number of patients is tiny—for goodness' sake!" Holmes said the Korean study has proved that stenting and surgery are equivalent in these patients and that, in most cases, the choice of procedure should come down to the individual patient.

But others were concerned that the widely acknowledged expertise of the Koreans—who pioneered stenting of the left main coronary artery—may have skewed the results of this registry data, and many, including the Korean researchers themselves, say that a randomized controlled trial is required before worldwide practice is changed.

SYNTAX trial eagerly awaited

In an editorial accompanying the paper [2], Dr Robert H Jones (Duke University Medical Center, Durham, NC), says: "I do not think readers should be seduced by the compelling case for equivalence of these two revascularization techniques that is made by . . . the MAIN-COMPARE study."

Others polled by heartwire had similar views. Dr Tim Gardner (Christiana Care Health Center, Wilmington, DE) said: "In the US, there is very little experience with left main stenting, and there is lots of caution about it. I'm surprised the results of the Korean team are so good. But if the technique is as safe as their data suggest, it would certainly be a step forward." However, he cautioned, "We have to be careful with these gee-whiz types of trials. It is very important that we do a randomized controlled trial and that this is expanded to include centers in North America and Europe."

In fact, such a randomized trial is under way, the SYNTAX study, and other experts said this would help guide practice. Dr Patrick Serruys (Thoraxcenter, Rotterdam, the Netherlands) told heartwire: "Dr Park was and is a pioneer, and through his excellent teaching many places in the world are now gaining quite acceptable results, and there are a number of registries." Having said that, said Serruys, the results of SYNTAX, expected in September, will yield much-needed information.

Moderator of the press conference, Dr E Murat Tuzcu (Cleveland Clinic, OH), agreed: "Left main disease was always thought of as a no-man's-land for interventionalists, but this study is reassuring in terms of safety and mid-term results. However, the SYNTAX study has large numbers and should prove very helpful."

Some of the first long-term data on stents in left main disease

Significant narrowing of the left main coronary artery has the worst prognosis of any form of coronary artery disease, the Korean researchers explain in their paper. CABG has been considered standard therapy for patients with left main coronary disease and is recommended by current practice guidelines. However, the availability of drug-eluting stents (DES) has led to the reevaluation of the role of PCI for left main disease. Nevertheless, there are limited data on the long-term safety and effectiveness of PCI with bare-metal or drug-eluting stents, they note.

In his presentation of long-term data from the Korean MAIN-COMPARE registry, Park said stenting of the left main coronary artery has been more commonplace in Korea than in Western countries.

The researchers evaluated 1102 patients with unprotected left main coronary disease who underwent stent implantation and 1138 patients who underwent CABG at 12 major cardiac centers in Korea between January 2000 and June 2006. Prior to 2003, bare-metal stents were employed in PCI; after the second quarter of 2003, DES were used exclusively.

They compared adverse outcomes (death; a composite outcome of death, Q-wave MI, or stroke; and TVR) using propensity-score matching in the overall cohort and in separate subgroups according to type of stent.

Park explained that propensity-score matching was employed because of baseline differences between the stent and surgery groups. The median follow-up was 2.8 years in the PCI cohort and 3.2 years in the CABG group. All patients received aspirin indefinitely, and those who received bare-metal stents received clopidogrel or ticlopidine for one month, while those who had a DES implanted took clopidogrel for six months.

Stenting and surgery equivalent except for TVR rates

The risks of death and the composite end point were similar in the PCI and CABG groups. These results were consistent when bare-metal stents or DES were compared with CABG, although there was a nonsignificant trend toward higher risk with DES, Park noted.

The rate of TVR was significantly lower in the CABG group than in the PCI group, however, with hazard ratios varying depending on the type of stent. Those receiving DES were almost six times as likely to require revascularization as those who underwent surgery, and bare-metal-stent recipients almost 10 times as likely.

But the researchers note in their paper that there was a significantly higher rate of follow-up angiography in the PCI group than in the CABG group (73% vs 14.6%; p<0.001), "so the rate of asymptomatic graft stenosis or occlusion may have been underestimated in the CABG group relative to the PCI group."

Hazard ratios for clinical outcomes after stenting as compared with after CABG among propensity-matched patients

Outcome	Overall cohort HR (n=542 pairs)	p	Wave 1 HR (n=207 pairs)	p	Wave 2 HR (n=396 pairs)	p
Death	1.18	0.45	1.04	0.90	1.36	0.26
Death, Q-wave MI, or stroke	1.10	0.61	0.86	0.59	1.40	0.15
TVR	4.76	<0.001	10.70	<0.001	5.96	<0.001

In conclusion, Park told heartwire that experience of stenting left main coronaries across the world varies to such an extent that randomized trial data are still essential before practice is changed.

In his editorial, Jones says the MAIN-COMPARE study offers reassurance that such a randomized trial can be conducted without jeopardizing patients' safety. "MAIN-COMPARE supports but does not eliminate the need for a well-designed and adequately powered prospective randomized trial of the two revascularization strategies in patients with unprotected left main disease," he concludes.