SYNTAXES Study: No Significant Difference In All-Cause Death At 10 Years Between PCI and CABG Results of a 10-year Follow-up Study presented at the European Society of Cardiology (ESC) Congress 2019

A follow-up of a multicenter, randomized controlled trial, the results of which were debuted at the European Society of Cardiology (ESC) Congress 2019, has shown that at 10 years, no statistically significant difference existed in all-cause mortality between percutaneous coronary intevention (PCI) using first-generation paclitaxel-eluting stents and coronary artery bypass grafting (CABG). However, CABG was shown to provide significant survival benefit in patients with three-vessel disease, but not in patients with left main coronary artery disease.

The SYNTAX Extended Survival (SYNTAXES) study by Thuijs D. et al. and published in The Lancet, is an investigator-driven extension of follow-up of SYNTAX trial, a multicenter, randomized controlled trial conducted at 85 centers across the North America and Europe. A total number of 1800 patients were randomly assigned to the PCI (903 patients) or CABG (897 patients) group.  Subject-exclusion criteria involved a history of CABG or PCI, acute myocardial infarction, or an indication for concomitant cardiac surgery.  Patients with de novo three-vessel and left main coronary artery disease were randomly assigned with a 1 to 1 ratio to the PCI or CABG group. The primary endpoint of the study was 10-year all-cause mortality, which was evaluated according to the intention-to-treat principle. Prespecified subgroup analyses were done based on the presence or absence of left main coronary artery disease and diabetes, and according to coronary complexity defined by core laboratory SYNTAX score tertiles.

The investigators found out that at 10 years, 244 (27%) patients had died after PCI and 211 (24%) after CABG (hazard ratio 1.17 [95% CI: 0.97 – 1.41], P = 0.092). Among the patients with three-vessel disease, 151 (28%) of the 546 had died after PCI versus 113 (21%) of the 549 after CABG [hazard ratio 1.41 [95% CI: 1.10 – 1.80]. Among the patients with left main coronary artery disease, 93 (26%) of 357 had died after PCI versus 98 (28%) of 348 after CABG (0.90 [0.68 – 1.20], P [interaction] = 0.019). There was no treatment-by-subgroup interaction with diabetes (P [interaction] = 0.66) and no linear trend across SYNTAX score tertiles (P [trend] = 0.30).

The SYNTAX, a prospective clinical trial, had shown that the rates of major adverse cardiac or cerebrovascular events at 12 months are significantly higher in the PCI group (17.8%, vs. 12.4% for CABG; P = 0.002), mainly because of an increased rate of repeat revascularization (13.5% vs. 5.9%, P < 0.001). At 1-year follow-up, the rates of death and myocardial infarction were same in both groups; with stroke more likely occurring in the CABG group (2.2%, vs. 0.6% with PCI; P = 0.003). At 5-year follow-up, the overall adverse-event rate was lower with CABG (27%) than with PCI (37%; P < 0.001). The rates of death and stroke did not significantly differ. The rates of myocardial infarction and repeat revascularization were higher with PCI than with CABG (9.7% vs. 3.8% and 26% vs. 14%, respectively).

The study was limited by the small number of patients at risk at maximum follow-up. Other limitations include all-cause death being the only endpoint and the absence of assessment of additional outcomes, such as myocardial infarction, stroke, stent thrombosis, and graft occlusion.