The two-year results from the SYNTAX study suggesting that coronary artery bypass grafts (CABG) may be more appropriate for patients with complex three-vessel (3VD) and/or left main coronary (LM) disease; while percutaneous coronary intervention (PCI) may be an acceptable alternative for patients with less complex disease.
SYNTAX was a prospective, multinational, randomized clinical trial designed to compare PCI with CABG for the treatment of de novo 3VD and/or LM disease. All subjects were screened by a cardiac surgeon and interventional cardiologist. Those eligible for either treatment were randomized to PCI or CABG, stratified by LM disease and diabetes. Subjects suitable for only one treatment were entered into the appropriate SYNTAX registry. All randomized subjects were assigned a SYNTAX Score, a novel angiographic tool used to measure the complexity of coronary artery disease based on 9 anatomic criteria, including lesion frequency, complexity and location [www.syntaxscore.com]. Higher SYNTAX Scores indicate patients with more complex disease and increased treatment challenges.
A total of 1800 patients were randomized at 85 sites (CABG, n=897: PCI, n=903). Subjects were mean age 65 years; approximately 25% had diabetes. Mean total SYNTAX Score was 29.1 in the CABG arm and 28.4 in the PCI arm. The mean number of lesions was 4.4 in the CABG arm and 4.3 in the PCI arm. Most patients (~66%) had 3VD; approximately 34% had LM disease, most with multiple vessel involvement [Serruys PW et al. N Engl J Med 1009].
After 2 years, the primary endpoint of SYNTAX, major adverse cardiac and cerebrovascular events (MACCE; defined as a composite of all-cause death, stroke, myocardial infarction (MI), and repeat revascularization), was significantly (p<0.001) higher in the PCI arm due, in large part, to increased repeat revascularization (PCI 17.4% vs CABG 8.6%). The composite safety endpoint of death/stroke/MI was comparable between the 2 groups. The rate of MI was significantly increased in PCI patients whereas stroke remained significantly higher in CABG patients after 2 years of follow-up (Table 1).
Table 1. Two-year Adverse Event Rates (Time-to-Event).
|
CABG |
PCI |
p-value |
MACCE |
16.3 |
23.4 |
0.0002 |
Death/Stroke/MI |
9.6 |
10.8 |
NS |
Death, all cause |
4.9 |
6.2 |
NS |
Stroke |
2.8 |
1.4 |
0.03 |
MI |
3.3 |
5.9 |
0.01 |
Repeat revascularization |
8.6 |
17.4 |
<0.0001 |
MACCE = composite of all-cause death, stroke, MI, and repeat revascularization;
The impact of lesion complexity on 2-year clinical outcomes was estimated by examining patient outcomes relative to SYNTAX Score tercile (low = 0-22; intermediate = 23-32; high ≥33). The rates of MACCE were not significantly different between patients with low SYNTAX Scores treated with either PCI or CABG (CABG 17.4% vs PCI 19.4%; p=0.63). In patients with intermediate SYNTAX Scores, there was a trend towards increased MACCE with PCI (CABG 16.4% vs PCI 22.8%; p=0.06). In the most complex patients (SYNTAX Scores ≥33), MACCE was significantly increased in patients treated with PCI (CABG 15.4% vs PCI 28.2%; p=0.0001).
A subgroup analysis of patients with left main disease suggest that a new study is warranted to evaluate whether PCI is an alternative to CABG in patients with left main disease and low syntax score. This new study named EXCEL is currently under development.
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