PARIS, France—In patients with triple-vessel disease, percutaneous coronary intervention (PCI) increases the risk for serious adverse events compared with coronary artery bypass graf (CABG) surgery, and the disadvantage grows with increasing Syntax score, according to registry data presented August 29, 2011, at the European Society of Cardiology Congress.

In view of this finding, CABG should remain the preferred treatment, especially for those with higher Syntax scores. But even for patients with less complex coronary anatomy, PCI yields worse outcomes than CABG and should be used judiciously, said Hiroki Shiomi, MD, of Kyoto University (Kyoto, Japan).

Hints from SYNTAX

Results from the SYNTAX trial suggested that PCI was associated with a higher risk of death, MI, or stroke in patients with high or intermediate Syntax scores but not in those with low scores. However, the triple-vessel subset in the trial was underpowered to reliably evaluate that composite endpoint, Dr. Shiomi pointed out.

For the current study, investigators analyzed data from 2,981 patients with triple-vessel disease who underwent a first coronary revascularization—either CABG (n = 1,156) or PCI (n = 1,825)—at 1 of 26 Japanese centers between January 2005 (after the first DES were approved in Japan) and December 2007. The patients were enrolled in the CREDO-Kyoto PCI/CABG Registry Cohort-2.

In the PCI arm, 95% of patients received stents and 77% were implanted with DES.

PCI patients were older, heavier, and had more hypertension, while CABG patients had more diabetes, renal dysfunction, prior MI, and worse left ventricular function. In terms of procedural characteristics, PCI was more often performed on an emergency basis, while CABG was more likely to be performed for chronic total occlusions.

After 3 years, rates for the primary outcome (all-cause death, MI, or stroke) favored CABG. Surgery also substantially reduced rates of MI and revascularization. Although there were more all-cause deaths in the PCI group, cardiac death and stroke were similar for the 2 therapies (table 1).

Table 1. Cumulative Outcomes at 3 Years

What’s the Score?

Outcomes were also analyzed according to Syntax score, an angiographic tool for assessing the severity of coronary anatomy derived from the SYNTAX trial. Scores were available in 98.2% of PCI patients and 88.2% of CABG patients. The mean score was 23.6 ± 9.2 in the PCI arm and 30.0 ±10.5 in the CABG arm.

To compare similar-risk groups, patients in both treatment arms were stratified into tertiles of Syntax score:

• Low (< 23)
• Intermediate (23 to < 33)
• High (≥ 33)

Unadjusted risk for serious adverse events was not different between PCI and CABG in patients with low and intermediate scores. However, after adjustment, the risk of PCI was higher in patients with the lowest and highest scores (table 2).

Table 2. Primary Endpoint: PCI vs. CABG According to Syntax Score

Clinical outcome after PCI was adversely influenced by increasing Syntax scores, with the incidence of the primary endpoint rising from 15.8% for low scores to 18.8% for intermediate scores and 27.0% for high scores (P< 0.001). On the other hand, CABG outcomes were largely unaffected by the complexity of coronary anatomy (12.5% for low scores, 16.7% for intermediate scores, and 16.4% for high scores; P = 0.37).

“These findings are consistent with those from the original SYNTAX trial,” Dr. Shiomi noted. “And the protective effect of CABG for MI was particularly remarkable.

“Further studies are warranted to investigate whether PCI is a viable option in patients with less complex coronary anatomy,” he added.

Discussant Frans Van de Werf, MD, PhD, of University Hospitals Leuven (Leuven, Belgium), said that these data confirm the overall results of the SYNTAX trial, showing the advantage of CABG over PCI, in a large real-world population. But he acknowledged that the finding that CABG is favored even in patients with a low Syntax score was “a big surprise,” and needs to be replicated in future trials.

The study also suggests the usefulness of the Syntax score in clinical practice, Dr. Van de Werf said, although he stressed that in both SYNTAX and the CREDO-Kyoto registry, the Syntax score was applied retrospectively. “What we need is a use of this important Syntax score prospectively to allocate patients either to PCI or CABG,” he commented.

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