Extended 10-year follow-up has demonstrated that in patients with a high SYNTAX score undergoing left main coronary artery (LMCA) revascularisation there is a clear prognostic benefit for coronary artery bypass graft (CABG) over percutaneous coronary intervention (PCI). PCI was associated with similar mortality and serious composite outcomes in patients with low to intermediate SYNTAX scores.
The findings from the MAIN COMPARE registry (Ten-year outcomes of stents versus coronary-artery bypass grafting for left main coronary artery disease) were published in JACC: Cardiovascular Interventions, by Yong-Hoon Yoon (Chungnam National University Hospital, Chungnam National University School of Medicine, Daejeon, South Korea) et al.
They say: “The adjusted 10-year rates of mortality and serious composite outcome were similar after PCI and CABG in patients with low to intermediate anatomic complexity measured by baseline SS [SYNTAX score]. However, CABG showed a clear 10-year long-term benefit over PCI in patients with high anatomic complexity. This study also demonstrates that the SS has a significant correlation with mortality and major adverse events in patients who underwent PCI but not in those who underwent CABG.”
Patients with baseline SYNTAX score measurements in the MAIN COMPARE registry were analysed and the 10-year rates of all-cause mortality, the composite of death, Q-wave myocardial infarction, or stroke, and target vessel revascularisation after PCI or CABG were compared according to baseline SYNTAX score.
In all 2,240 patients with unprotected LMCA disease were enrolled in the registry between January 2000 and June 2006. The SYNTAX score was not available for 660 patients, leaving 1,580 patients for analysis in this study. Of these, 897 patients (56.8%) were categorised into the low- to intermediate SYNTAX score group (547 [34.6%] with low SYNTAX score of ≤22, and 350 [22.2%] with intermediate SS of 23 –32); 683 (43.2%) patients were categorised into the high SS (≥33) group. In 897 patients with low to intermediate SS, 633 (71%) underwent PCI, and 264 (29%) underwent CABG. Among 683 patients with high SYNTAX score, 186 (27%) underwent PCI, and 497 (73%) underwent CABG.
The researchers found that in patients with low to intermediate SYNTAX score, the adjusted 10-year risks for death and serious composite outcome were similar between the PCI group and the CABG group. However, in patients with high SYNTAX score, PCI was associated with a higher risk for death (hazard ratio [HR] 1.39, 95% confidence interval (CI) 1–1.92, p=0.048) and serious composite outcome (HR 1.27, 95% CI 0.94–1.74, p=0.123) compared to CABG. In each revascularisation group, conventional tertiles of SYNTAX score had a differential prognostic impact on 10-year clinical outcomes in the PCI arm, but not in the CABG arm.
Limitations were that the study was observational and should be considered hypothetical and hypothesis generating only, and the findings are subject to selection bias. In addition, 30% of the total study population was excluded because baseline SYNTAX score measurement was not available, and clinical outcomes of bare metal stents (BMS) or first-generation drug eluting stents (DES) were evaluated in the PCI arm. Therefore, say Yoon et al, further evaluation through extended follow-up of the EXCEL and NOBLE trials using contemporary generation DES “may provide more compelling evidence on the long-term effect of contemporary PCI and CABG in patients with LMCA disease according to anatomic complexity measured by SS”.
In an accompany comment, Bernard Chevalier (Institut Cardiovasculaire Paris Sud, Massy, France) says the investigators should be congratulated, particularly “considering the paucity of follow-up data beyond five years”. However, he suggests that the “central role in the decision-making process” played by angiographic evaluation by means of the SYNATX score is “outdated”, describing it as only one of the criteria to be considered by the heart team.
Corresponding author Duk-Woo Park (University of Ulsan College of Medicine 88, Seoul, South Korea) also underlined the need for an overview. He told Cardiovascular News: “The SYNTAX score is not sole factor used to decide optimal revascularisaton. Therefore, further factors such as clinical, anatomical, and/or physician or patient preferences should be considered in heart-team discussions.”
And he stressed: “Our study might have novelty to evaluate the SYNTAX score in left main revascularisation during long-term follow-up beyond 10 years, data for which are still limited. Assessment of the discriminative value of SYNTAX score was limited in the recent EXCEL and NOBLE trials, and therefore, further study is required.”