Commentary: Mobilizing the reserves in coronary artery bypass grafting with and without fractional flow

Central MessageFor optimal surgical care, we need to mobilize all our reserves and improve graft patency, including fractional flow (eg, multiarterial grafting, improved vein handling, and surgeon specialization).See Article page 74. For optimal surgical care, we need to mobilize all our reserves and improve graft patency, including fractional flow (eg, multiarterial grafting, improved vein handling, and surgeon specialization). See Article page 74. Ever since the introduction of percutaneous coronary intervention (PCI) for the treatment of chronic coronary artery disease (CAD), there has been hope of curing CAD mechanically without exposing the patient to much more invasive coronary artery bypass surgery (CABG). Hefty controversies have created somewhat of a “battlefield of PCI and CABG” (see the EXCEL trial data controversy1Cohan D. Brown E. Is the tide turning on the “grubby” affair of EXCEL and the European guidelines? 2020.https://www.medscape.com/viewarticle/939944Date accessed: September 11, 2020Google Scholar), where different guideline interpretations and possibly other incentives resulted in ratios of PCI to CABG performance ranging from approximately 2:1 in one country to more than 10:1 in the next.2Figulla H.R. Lauten A. Maier L.S. Sechtem U. Silber S. Thiele H. Percutaneous coronary intervention in stable coronary heart disease: is less more?.Dtsch Arztebl Int. 2020; 117: 137-144Google Scholar From a patient perspective, such differences should be acceptable only if treatment effects are similar. However, results may differ significantly,3Head S.J. Milojevic M. Daemen J. Ahn J.M. Boersma E. Christiansen E.H. et al.Mortality after coronary artery bypass grafting versus percutaneous coronary intervention with stenting for coronary artery disease: a pooled analysis of individual patient data.Lancet. 2018; 391: 939-948Abstract Full Text Full Text PDF PubMed Scopus (255) Google Scholar and we recently suggested that CABG and PCI differ in their mechanisms.4Doenst T. Haverich A. Serruys P. Bonow R.O. Kappetein P. Falk V. et al.PCI and CABG for treating stable coronary artery disease: JACC review topic of the week.J Am Coll Cardiol. 2019; 73: 964-976Crossref PubMed Scopus (82) Google Scholar CABG, in addition to revascularizing chronically ischemic myocardium, provides protection against new myocardial infarctions by creating “surgical collaterals.” Collaterals can prevent infarctions if a proximal coronary lesion causes vessel occlusion. This infarct preventative effect appears to be responsible for the survival effect of invasive CAD therapy.4Doenst T. Haverich A. Serruys P. Bonow R.O. Kappetein P. Falk V. et al.PCI and CABG for treating stable coronary artery disease: JACC review topic of the week.J Am Coll Cardiol. 2019; 73: 964-976Crossref PubMed Scopus (82) Google Scholar Since most infarct-causing lesions are not stented, CABG's advantage over PCI emerges with increasing risks for new myocardial infarctions.4Doenst T. Haverich A. Serruys P. Bonow R.O. Kappetein P. Falk V. et al.PCI and CABG for treating stable coronary artery disease: JACC review topic of the week.J Am Coll Cardiol. 2019; 73: 964-976Crossref PubMed Scopus (82) Google Scholar This effect requires patent bypass grafts; however, graft occlusions are common (up to 50% at 10 years5Gaudino M. Antoniades C. Benedetto U. Deb S. Di Franco A. Di Giammarco G. et al.Mechanisms, consequences, and prevention of coronary graft failure.Circulation. 2017; 136: 1749-1764Crossref PubMed Scopus (74) Google Scholar). Thus, it may be time to mobilize our reserves to improve graft patency, including multiarterial grafting, surgeon specialization, and/or improved vein harvesting and handling techniques.6Gaudino M. Benedetto U. Bakaeen F. Rahouma M. Tam D.Y. Abouarab A. et al.Off- versus on-pump coronary surgery and the effect of follow-up length and surgeons' experience: a meta-analysis.J Am Heart Assoc. 2018; 7: e010034Crossref PubMed Scopus (29) Google Scholar, 7Rosati C.M. Torregrossa G. Balkhy H.H. Puskas J.D. Dedicated training in advanced coronary surgery: need and opportunity.J Thorac Cardiovasc Surg. April 18, 2020; ([Epub ahead of print])Abstract Full Text Full Text PDF PubMed Scopus (5) Google Scholar, 8Samano N. Geijer H. Liden M. Fremes S. Bodin L. Souza D. The no-touch saphenous vein for coronary artery bypass grafting maintains a patency, after 16 years, comparable to the left internal thoracic artery: a randomized trial.J Thorac Cardiovasc Surg. 2015; 150: 880-888Abstract Full Text Full Text PDF PubMed Scopus (131) Google Scholar, 9Taggart D.P. Webb C.M. Desouza A. Yadav R. Channon K.M. De Robertis F. et al.Long-term performance of an external stent for saphenous vein grafts: the VEST IV trial.J Cardiothorac Surg. 2018; 13: 117Crossref PubMed Scopus (19) Google Scholar Our current decision making for PCI or CABG is based on outcomes from the CABG trial, with patients not always having received our best. The collateralization hypothesis would require all diseased territories to be grafted. However, besides surgical technicalities, graft patency is also affected by the flow relevance of coronary lesions. Fractional flow reserve (FFR) assesses the functional flow relevance of coronary lesions and has improved outcomes in PCI (primarily by reducing the need for re-revascularization). In this issue of the Journal, Glineur and colleagues10Glineur D. Chong A.Y. Grau J. What should be the role of fractional flow reserve measurement in patients undergoing coronary artery bypass grafting?.J Thorac Cardiovasc Surg Open. 2021; 5: 74-79Google Scholar elegantly review the value of FFR for CABG. For fully arterial CABG, it indeed allows the prediction of graft occlusions. At an FFR value <0.78, 97% of grafts were perfect at 6 months. At higher values, the risk of occlusion increased, depending on graft targets (circumflex or right) and configuration (single vs sequential). Two findings appear to be most important in this context. First, the detected graft occlusions were clinically silent. Thus, grafting a diseased vessel with a 50% risk of occlusion would still provide infarct protection in the other 50% without adding harm. Second, vein grafts do not appear to be as sensitive to competitive flow, suggesting that other mechanisms may be more relevant for graft failure. Thus, applying strategies to improve vein patency, such as no-touch techniques8Samano N. Geijer H. Liden M. Fremes S. Bodin L. Souza D. The no-touch saphenous vein for coronary artery bypass grafting maintains a patency, after 16 years, comparable to the left internal thoracic artery: a randomized trial.J Thorac Cardiovasc Surg. 2015; 150: 880-888Abstract Full Text Full Text PDF PubMed Scopus (131) Google Scholar or external stenting,9Taggart D.P. Webb C.M. Desouza A. Yadav R. Channon K.M. De Robertis F. et al.Long-term performance of an external stent for saphenous vein grafts: the VEST IV trial.J Cardiothorac Surg. 2018; 13: 117Crossref PubMed Scopus (19) Google Scholar may be attractive options in case veins are required. Glineur and coauthors conclude that FFR should not be used to decide between PCI and CABG. However, it can be used to improve graft type selection and thereby enhance our ability to provide more patients with patent grafts. On the battlefield of invasive CAD therapy, graft patency is key.4Doenst T. Haverich A. Serruys P. Bonow R.O. Kappetein P. Falk V. et al.PCI and CABG for treating stable coronary artery disease: JACC review topic of the week.J Am Coll Cardiol. 2019; 73: 964-976Crossref PubMed Scopus (82) Google Scholar Therefore, it is time to mobilize all our reserves, with and without fractional flow. What should be the role of fractional flow reserve measurement in patients undergoing coronary artery bypass grafting?JTCVS OpenVol. 5PreviewFeature Editor's Introduction—Glineur and colleagues from Ottawa present a superb summary on the evidence of the use of fractional flow reserve (FFR) for coronary bypass surgery. FFR was conceived to guide percutaneous coronary interventions, a procedure that targets directly the culprit plaque and whose success is inversely related to the complexity and the numbers of the lesions treated. In this context, a tool able to identify the flow-limiting lesions and reduce the procedural complexity and the number of stents implanted makes obvious sense. Full-Text PDF Open Access

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