FREEDOM, SYNTAX, FAME and FUNCTIONALITY

The Future of Surgical Revascularization in Stable Ischemic Heart Disease

T Bruce Ferguson Jr; Cheng Chen

Future Cardiol. 2014;10(1):63-79.

Abstract

At the age of nearly 50 years, the procedure of coronary artery bypass grafting (CABG) now has the most solid evidence supporting its role in revascularization for stable ischemic heart disease in its history. In what is a relatively infrequent occurrence in medicine, the results from large-scale observational database analyses are now aligned with and supported by data from recent randomized trials, providing important contemporary evidence in support of CABG. However, even with strong evidence, the changing landscape of revascularization for stable ischemic heart disease threatens to make this evidence irrelevant in deciding which patients should be referred for CABG in the future. How the procedure of CABG could be modified and optimized for incorporation into this new landscape is discussed in this article.

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Future Cardiol. 2014;10(1):63-79. © 2014 Future Medicine Ltd.

Box 1. Questions for the future of surgical revascularization.
*Long-term mortality benefit of CABG*
What is the relationship between intermediate-term graft attrition and long-term survival in CABG? If both SYNTAX and FREEDOM were anatomy-based intervention trials, what (besides anatomy) could be the mechanism(s) of the survival benefit with CABG?
*The role of functionality: FFR-guided CABG*
What is the fate of nonarterial grafts placed beyond an anatomic but not functional stenosis? What is the fate of arterial grafts placed beyond an anatomic but not functional stenosis? Is the deliberate nonplacement of grafts beyond anatomic but nonfunctional stenoses harmful? Does the current anatomy-based practice of routine placement of grafts beyond anatomic stenoses, with and without functionality, contribute to the mortality advantage of CABG seen in FREEDOM and SYNTAX, and observational studies?
*The role of myocardial integrity*
How does myocardial viability, viable but ischemic myocardium and nonviable myocardium impact on TVECA grafting? How does the pre-existing collateral substrate affect the perfusion outcomes from CABG? What if collateral flow from TVECAs grafted at surgery changed the perfusion to regions targeted for concomitant adjunctive therapies? What impact do changes in regional TVECA perfusion have on other areas of myocardium supplied by other TVECAs? Is perfusion change to the myocardium, beyond anastomotic patency, a new end point in surgical revascularization?
*Revascularization completeness*
If grafts beyond anatomic stenoses are more likely to fail at 1 year, how can their construction be linked to long-term protection from cardiac death and MI? Given a transition to functional-based revascularization, how do surgeons assess the efficacy of 'reasonable incomplete revascularization' at the time of CABG?

CABG: Coronary artery bypass grafting; FFR: Fractional flow reserve; MI: Myocardial infarction; TVECA: Target vessel epicardial coronary artery.

Box 2. Possible mechanisms for the mortality benefit with coronary artery bypass grafting.
Grafting beyond the stenosis is protective against subsequent events from disease progression Fewer cardiac events than PCI in the follow-up interval with CABG Possibly the same number of events as PCI, but an excess of flow and perfusion is created with graft plus native TVECA flow, providing intermediate and long-term protection against cardiac death and MI Better capitalization and optimization of existing myocardial integrity issues of viability, collateral flow and relief of ischemia 'More complete' reasonable incomplete revascularization

CABG: Coronary artery bypass grafting; MI: Myocardial infarction; PCI: Percutaneous coronary intervention; TVECA: Target vessel epicardial coronary artery.

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