Barcelona, Spain, 30 August: Important new evidence about revascularization in patients with severe coronary artery disease can be found in the recently published interim analyses of the SYNTAX Trial of 1,800 patients with left main and/or three vessel coronary artery disease randomised to PCI or CABG. The unique strength of Syntax was not only as an 'all-comer' trial of patients with the most complex coronary artery disease but the maintenance of a parallel registry of patients excluded from randomization (1077 CABG patients whose disease was too complex for PCI and 198 PCI patients considered to be at excessively high surgical risk).
At an interim analysis of one year (with final analyses at five years), 12% of CABG and 18% of PCI patients reached the primary composite end point of death, myocardial infarction, stroke or repeat revascularisation. While the difference was largely driven by repeat revascularization but with no significant difference in mortality, PCI failed to reach the pre-trial specified criteria for non-inferiority, with the authors concluding that 'CABG remains the standard of care for patients with three-vessel or left main coronary artery disease' (and in contrast to the current study did find a greater benefit of CABG with more severe disease). However the one year result may significantly underestimate the survival benefit of CABG which registry data has consistently shown to accrue with time in comparison to PCI and usually reaches statistical difference at 2-3 years.
Furthermore, although all PCI patients received drug eluting stents fewer than 30% of CABG patients benefited from the potential prognostic benefit of bilateral internal mammary artery grafts. Finally, it is uncertain whether the higher incidence of stroke at one year with CABG (2.2% vs 0.6%) was largely procedural or a consequence of substantially inferior secondary prevention (including dual antiplatelet, statin, antihypertensive and ACE inhibitor medication) than in the PCI group.
So what can we conclude from the current evidence and particularly in light of the recently published COURAGE and SYNTAX Trials? For less severe coronary disease (mainly one or two vessel disease and normal left ventricular function) there is little prognostic benefit from any intervention over optimal medical therapy. In such patients who do require intervention, perhaps for symptomatic reasons, there is no obvious survival advantage for either PCI or CABG (at least in non diabetic patients), but there is a significantly higher risk of repeat revascularisation with PCI.
In patients with more severe coronary artery disease, and especially those with diabetes, CABG is superior in terms of survival and freedom from reintervention. However, SYNTAX also underlined that PCI is a good option- at least over the shorter term- in patients who are ineligible for or who refuse CABG and also the importance of rigorous secondary prevention in CABG patients. Finally, in view of the prognostic benefit of surgery, a multi disciplinary team approach should be the standard of care when recommending interventions in more complex coronary artery disease, to ensure transparency, real patient choice and genuine informed consent in the decision making process. For elective patients this will necessitate separation of angiography from the intervention to allow appropriate time to make a truly informed decision.