The SYNTAX II study has found that percutaneous coronary intervention (PCI) using state-of-the-art techniques—including physiological assessment and a new-generation drug-eluting stent—significantly reduces the rate of major adverse cerebrovascular cardiac events (MACCE) in patients with de novo three-vessel disease compared with the PCI strategy used in the original SYNTAX trial. There are also indications that this best-practice strategy, known as the SYNTAX-II strategy, is non-inferior to coronary artery bypass grafting (CABG) in matched patients.
SYNTAX (Synergy between PCI with Taxus and cardiac surgery) suggested that for patients with three-vessel disease, CABG was the preferred revascularisation strategy; it showed that, in this patient cohort, PCI was associated higher rate of all-cause death, myocardial infarction, and repeat revascularisation at five years than was surgery.
However, speaking at the European Society of Cardiology (ESC) congress (26–30 August, Barcelona, Spain), Javier Escaned (Hospital Clinico San Carlos/Faculty of Medicine Complutense University, Madrid, Spain) noted that, following the completion of that study, “major technical and procedural advances, influencing PCI outcomes, have taken place”. These include the use of better patient risk stratification using the SYNTAX score II, second-generation drug-eluting stents (a paclitaxel-eluting stent was used in SYNTAX), physiological and imaging guidance, and improved chronic total occlusion PCI techniques. He added that the purpose of SYNTAX II, therefore, was to determine if PCI using these advances—“incorporated to form the SYNTAX II strategy”—would improve outcomes in patients with three-vessel disease compared with the PCI used in the SYNTAX study.
To be included in the multicentre, prospective, single-arm, open-label study, patients (454) had to have three-vessel disease with no left main stem left main involvement and be predicted to have (according to the SYNTAX II score; irrespective of their anatomic SYNTAX score) equipoise four-year mortality with PCI or with CABG. Following heart team discussion, those assigned to PCI (450) underwent physiological assessment with a hybrid instantaneous wave-free ratio (iFR; Philips Volcano)/fractional flow reserve (FFR) approach. With this approach, lesions with an iFR of <0.86 were treated with PCI, those with a iFR of 0.86–0.93 underwent further assessment with FFR (and subsequently were treated if they had a FFR of ≤0.80), and treatment was deferred in lesions with with a iFR of >0.93 (as were those with a FFR of >0.80).
A drug-eluting stent with a biodegradable polymer (Synergy, Boston Scientific) was the device used in the patients undergoing PCI and intravascular ultrasound (IVUS) was also used to ensure optimal stent deployment. Additionally, when relevant, contemporary chronic total occlusion techniques were used and guideline-directed medical therapy was prescribed after the PCI procedure.
Escaned reported that, compared with a matched cohort of patients (315) who underwent PCI in the original SYNTAX, study, the use of physiological assessment in SYNTAX II meant that fewer lesions per patient were treated (2.64 vs. 4.02, respectively; p<0.001) and fewer patients were deemed to have three-vessel disease (37.2% vs. 83.3%; p<0.001). He added that the procedural success rate of chronic total occlusion PCI was significantly higher in SYNTAX II: 87% vs. 53% for those SYNTAX PCI patients (p<0.0001).
At one year, the rate of MACCE—the primary endpoint—was significantly lower in the SYNTAX II cohort of patients than in the SYNTAX PCI cohort: 10.6% vs. 17.4% (p=0.006). Additionally, the rates of myocardial infarction (1.4% vs. 4.8%; p=0.007), any repeat revascularisation (8.2% vs. 13.7%; p=0.015), and definite stent thrombosis (0.7% vs. 2.7%; p=0.045) were all significantly lower in the patients who underwent PCI with the SYNTAX II strategy. However, there were no differences between cohorts in terms of all-cause death or stroke.
Escaned and colleagues also found that one-year outcomes of patients with a SYNTAX anatomical score of >22 treated with PCI in SYNTAX II (because the SYNTAX II score had indicated that they were eligible for PCI) were similar to those of patients with a low anatomical score. According to the SYNTAX study, CABG was preferable to PCI for patients with a SYNTAX anatomical score of >22. Furthermore, in an exploratory analysis, the rate of MACCE in the SYNTAX II cohort was compared with a matched cohort of patients from the CABG arm of the SYNTAX study. This did not find a significant difference between groups: 10.6% vs. 11.6% for the SYNTAX CABG cohort (p<0.001).
Escaned told Cardiovascular News that the results of SYNTAX II “reinforce the concept that combining scattered advancements in the management of patients with coronary artery disease result in better clinical outcomes”. He adds that the SYNTAX II strategy can be applied currently without difficulty “as of its components are at a hand of the interventionalist”. “The results of SYNTAX II are so good that we expect that the SYNTAX II strategy will be disseminated and subsequently adopted by many cardiologists,” Escaned observed.
Looking to the future, he notes that “a randomised clinical trial comparing the results of CABG and PCI is more indicated than ever”. He adds that such a trial should be “limited to those patients showing an equipoise between CABG and PCI, which constitutes a large number of patients who are currently treated with CABG, in agreement with clinical practice guidelines, on the grounds of the anatomical SYNTAX score.”
To coincide with its presentation at the ESC, SYNTAX II was simultaneously published in the European Heart Journal.