CORRESPONDENCE: LETTER TO THE EDITOR
Reply
David Glineur, MD*,
William D'hoore, MD, PhD,
Gebrine El Khoury, MD,
Sixte Sondji, MD,
Jean-Christophe Funken, MD,
Jean Rubay, MD, PhD,
Alain Poncelet, MD,
Parla Astarci, MD,
Robert Verhelst, MD,
Philippe Noirhomme, MD and
Claude Hanet, MD, PhD
* Service de Chirurgie cardiovasculaire et thoracique, Cliniques Universitaires Saint-Luc–U.C.L. 90, Avenue Hippocrate 10/6107, 1200 Bruxelles, Belgium (Email: david.glineur{at}clin.ucl.ac.be).
Dr. Kern wisely raised several points that were not discussed in our article (1). We are convinced of the interest of fractional flow reserve (FFR) as a tool to asses the physiological relevance of coronary stenoses, and we recently used this tool to compare the resistance to blood flow of several coronary graft configurations (2,3). Unfortunately, if all patients referred to bypass surgery underwent a pre-operative angiographic evaluation and if most of those angiographic documents could be analyzed quantitatively, very few patients would be referred to surgery with a full mapping of FFR on the different coronary segments.
In daily clinical practice, the use of FFR remains generally restricted to the evaluation of stenoses of intermediate severity and mainly in patients with <3-vessel disease who are planned to be treated by interventional cardiology. For patients referred to surgery with a 2- or 3-vessel disease, the decision to measure FFR for an intermediate stenosis associated with angiographically severe narrowing on other coronary segments is much less frequent, because the surgical indication is already present, on the basis of the critical lesions. In these cases, most cardiac surgeons choose to graft the intermediate lesion as well, even if this bypass is at risk of competitive flow. This attitude, although somewhat empirical, is based on the low risk expected from the possible occlusion of such nonfunctional grafts, on the hope that these grafts will remain patent long enough to provide some help in the case of progression of the intermediate lesion, and on the fear of a redo intervention, if lesion severity is underestimated. It still remains uncertain whether this is preferable to a more conservative attitude consisting of graft implantation only on severely narrowed coronary segments.
Several observations have illustrated the capacity of the internal thoracic artery (4) or right gastroepiploic artery (RGEA) (5) to recover function in the long term after having been found not functional (string sign) at early follow-up. This capacity seems related to endothelial protection mechanisms that are probably less prominent or totally absent in saphenous vein graft. Considering the natural progression of the disease on native vessels, this property could act in favor of RGEA in the longer term. The ongoing angiographic re-evaluation of the grafts at 3 years post-operatively could thus provide information susceptible to clarifying the meaning of these early findings, particularly in RGEA grafts with a balanced flow.
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References
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1. Glineur D, D'hoore W, El Khoury G, et al. Angiographic predictors of 6-month patency of bypass grafts implanted to the right coronary artery J Am Coll Cardiol 2008;51:120-125.[Abstract/Free Full Text]2. Glineur D, Poncelet A, El Khoury G, et al. Fractional flow reserve of pedicled internal thoracic artery and saphenous vein grafts 6 months after bypass surgery Eur J Cardiothorac Surg 2007;31:376-381.[Abstract/Free Full Text] 3. Glineur D, Noirhomme P, Reisch J, El Khoury G, Astarci P, Hanet C. Resistance to flow of arterial Y-grafts 6 months after coronary artery bypass surgery Circulation 2005;30(112 Suppl):I281-I285. 4. Feld H, Navarro V, Kleeman H, Shani J. Early postoperative occlusion of a left internal mammary artery bypass graft with subsequent restoration of patency Cathet Cardiovasc Diagn 1992;27:280-283.[CrossRef][Web of Science][Medline] 5. Eda T, Matuura A, Miyahara K, et al. Spontaneous restoration of patency in the free gastroepiploic artery graft: the living transplanted vascular system for coronary revascularization Ann Thorac Surg 2007;83:2219-2220.[Abstract/Free Full Text]
Related Article
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Limitations of Angiographic Predictors of Bypass Graft Patency
- Morton J. Kern
J. Am. Coll. Cardiol. 2008 52: 886-887.
[Full Text]
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