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PARIS -- Japanese patients with three-vessel disease and moderate to high SYNTAX scores fared better with bypass surgery compared with percutaneous coronary intervention (PCI), reaffirming the original SYNTAX trial results, according to a large registry study.

However, unlike the original trial, those with low scores also fared better with surgery, according to results of the study, which were presented here at the European Society of Cardiology meeting.

In the crude analysis of the CREDO-Kyoto (Coronary REvascularization Demonstrating Outcome Study in Kyoto) PCI/coronary artery bypass grafting (CABG) registry study, there was no difference in the primary outcome measure -- a composite of all-cause death, myocardial infarction, or stroke -- in patients with low to moderate (<32) SYNTAX scores at three years, but events were markedly higher for PCI in those with high scores (HR 1.68), according to Hiroki Shiomi, MD, from Kyoto University Hospital in Kyoto, Japan, and colleagues.

However, after adjusting for confounding factors, PCI was significantly associated with a higher risk for the primary outcome, even in patients with low SYNTAX scores:

• Low score: HR 1.66, 95% CI 1.04 to 2.65, P=0.03
• Intermediate score: HR 1.24, 95% CI 0.83 to 1.85, P=0.29
• High score HR 1.59, 95% CI 0.998 to 2.54, P=0.051

"The big surprise to me was that there was a benefit of CABG in patients with low SYNTAX scores, which was significant," said study discussant Frans Van de Werf, MD, from University Hospital in Leuven, Belgium, during a Hotline session at the meeting.

"This registry confirms the overall findings of the SYNTAX trial, which is a benefit of CABG, and this is now confirmed in a large real-world population," Van de Werf said.

Regarding individual secondary outcomes, CABG had "a remarkable protective effect for myocardial infarction," Shiomi said (incidence rate 2.5% for CABG versus 5% for PCI, adjusted HR 2.39).

Not surprisingly, PCI was associated with a higher risk of revascularization (adjusted HR 4.47), despite the use of drug-eluting stents, Shiomi said. The percutaneous strategy also increased risk of all-cause death (adjusted HR 1.62), mainly "driven by the excess in noncardiac death."

Investigators found no differences in rates of cardiac death or stroke.

In the original SYNTAX trial, a subset of patients with triple-vessel disease fared worse with PCI in the composite of death, MI, and stroke (14.8% versus 10.4%, P=0.04), as well as for all-cause death (9.5% versus 5.7%, P=0.02), Shiomi pointed out.

"Consistent with the observation in the SYNTAX randomized trial, PCI compared with CABG in our registry was associated with a significantly higher risk for serious adverse events in patients with three-vessel disease," Shiomi concluded.

The SYNTAX score, developed in the landmark SYNTAX trial, gives a quantitative evaluation of the severity of the coronary anatomy.

In the original trial, there was an overall suggestion that clinical outcomes with CABG were favorable in patients with severe coronary artery disease, especially as SYNTAX scores rose. However, major adverse cardiovascular and cerebrovascular events (MACCE) and repeat revascularization were significantly worse for PCI at three years.

"Shiomi's study confirms the original results, as well as the usefulness of the SYNTAX score in clinical practice," Van de Werf said. "Although, I have to stress, both in the SYNTAX trial, which was a randomized trial, and in this registry, the SYNTAX score was used retrospectively. We need to use this important SYNTAX score prospectively to allocate patients to either PCI or CABG."

In his presentation, Shiomi said that findings of a benefit for PCI in low score patients in the original SYNTAX trial are limited by an "apparent lack of statistical power in evaluating the primary endpoint" (P=0.75).

For the CREDO-Kyoto PCI/CABG registry cohort-2, researchers identified 2,981 patients with triple-vessel disease (PCI n=1,825; CABG n=1,156) among more than 13,000 with first coronary revascularization. The data came from 26 centers in Japan, spanning from January 2005 to December 2007.

Shiomi noted a few statistically significant differences between the PCI and CABG groups:

• PCI had more patients over 75 years old, 35% versus 26% (P<0.001)
• CABG had more patients with diabetes, 56% versus 50%, (P=0.002)
• CABG had more patients with a prior myocardial infarction, 25% versus 19% (P<0.001)
• CABG had more patients with renal insufficiency, 8.7% versus 5.6% (P<0.001)

He also pointed out that heart failure was high in both groups (about 20%), as was the prevalence of prior stroke (about 15%), and that drug-eluting stents were used in 77% of PCI patients.

In addition, these differences in clinical characteristics were significant at P<0.001:

• Number of target lesions: 3.44 versus 2.05, CABG/PCI
• Target of proximal left anterior descending artery: 97% versus 64%, CABG/PCI
• Target of chronic total occlusions: 51% versus 23%, CABG/PCI

The SYNTAX score was higher in the CABG cohort: 30 versus 23.6. While adverse events rose in accordance with the SYNTAX score in the PCI group (P<0.001), the same was not true in the CABG cohort (P=0.37).

"CABG will still remain the standard treatment option in patients with three-vessel disease, particularly when their SYNTAX scores are high," he said.

He added that the use of PCI in patients with high SYNTAX score should be "seriously discouraged unless the operative risk is prohibitively high."

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