Minimally invasive harvesting (MIVH) of the great saphenous vein for coronary artery bypass grafting (CABG) has been shown to reduce patient-related morbidity in the postoperative period as compared with conventional vein harvesting (CVH), and can be considered to be a cost-effective option. Although the effect of MIVH on patient morbidity from wound-related complications has been extensively investigated in the literature, the effect on the quality of the harvested conduit is less clear [1Athanasiou T. Aziz O. Skapinakis P. et al.Leg wound infection after coronary artery bypass grafting: a meta-analysis comparing minimally invasive versus conventional vein harvesting.Ann Thorac Surg. 2003; 76: 2141-2146Abstract Full Text Full Text PDF PubMed Scopus (94) Google Scholar, 2Rao C. Aziz O. Deeba S. et al.Is minimally invasive harvesting of the great saphenous vein for coronary artery bypass surgery a cost-effective technique?.J Thorac Cardiovasc Surg. 2008; 135: 809-815Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar]. However, before attempting this comparison, it is important to consider the characteristics that would be expected of a high-quality conduit, namely its macroscopic appearance, histologic quality (with particular regard to endothelial continuity), functional characteristics, and mid-term and long-term patency [3Aziz O. Athanasiou T. Panesar S.S. et al.Does minimally invasive vein harvesting technique affect the quality of the conduit for coronary revascularization?.Ann Thorac Surg. 2005; 80: 2407-2414Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar]. The ultimate measure of quality of a conduit used for CABG is its long-term patency reassuring an optimal clinical outcome based on freedom from cardiovascular events avoiding disability, which can compromise a patient's quality of life. In their observational study, Ouzounian and colleagues [4Ouzounian M. Hassan A. Buth K.J. et al.Impact of endoscopic versus open saphenous vein harvest techniques on outcomes after coronary artery bypass grafting.Ann Thorac Surg. 2010; 89: 403-409Abstract Full Text Full Text PDF PubMed Scopus (74) Google Scholar] have demonstrated this effect. This is an important finding that also counteracts the recently published article from Lopes and colleagues [5Lopes R.D. Hafley G.E. Allen K.B. et al.Endoscopic versus open vein-graft harvesting in coronary-artery bypass surgery.N Engl J Med. 2009; 361: 235-244Crossref PubMed Scopus (274) Google Scholar], which concluded that it may be an increased risk of worse outcomes with endoscopic harvesting, and its adoption in the current clinical cardiothoracic practice should be weighed against its known short-term benefits. There is no doubt that the validity of research findings increase as data accumulate. In the “Proteus phenomenon” between the first published studies [5Lopes R.D. Hafley G.E. Allen K.B. et al.Endoscopic versus open vein-graft harvesting in coronary-artery bypass surgery.N Engl J Med. 2009; 361: 235-244Crossref PubMed Scopus (274) Google Scholar] on a scientific question (mid-term patency after EVH), it may be shown to be the most extravagant effect size. This is followed by the publication of another study [4Ouzounian M. Hassan A. Buth K.J. et al.Impact of endoscopic versus open saphenous vein harvest techniques on outcomes after coronary artery bypass grafting.Ann Thorac Surg. 2010; 89: 403-409Abstract Full Text Full Text PDF PubMed Scopus (74) Google Scholar] that shows a large contradicting effect. Subsequent studies report effect sizes between these extremes. In the past, we had limited research findings, and currently we have too many. This makes science exciting, but we do not know exactly what these findings mean and how we can make better use of them. Credibility of research findings looks like a pyramid where the base is broad (ie, many findings have low credibility) and the top is narrowed (ie, few findings have high credibility). Randomized trials can test findings that are somewhere between the middle to the top of this credibility pyramid. Selection of questions should be strategic and systematically evidence-based. In summary we need to assess critically the following two important referenced studies [4Ouzounian M. Hassan A. Buth K.J. et al.Impact of endoscopic versus open saphenous vein harvest techniques on outcomes after coronary artery bypass grafting.Ann Thorac Surg. 2010; 89: 403-409Abstract Full Text Full Text PDF PubMed Scopus (74) Google Scholar, 5Lopes R.D. Hafley G.E. Allen K.B. et al.Endoscopic versus open vein-graft harvesting in coronary-artery bypass surgery.N Engl J Med. 2009; 361: 235-244Crossref PubMed Scopus (274) Google Scholar]. First, both studies had the following methodological drawbacks:1The clustering and the hierarchical structure of the data presented were not addressed to an appropriate extent. The sequence of clustering can affect the causes of variation as conduit to coronary target (coronary anastomosis) lies within the patient, which lies within the surgeon who lies within the cardiac center. Multilevel statistical models can handle this complex variation and can disentangle processes operating at different levels.2These studies did not avoid paradoxical comparisons (eg, the Lopes and colleagues [5Lopes R.D. Hafley G.E. Allen K.B. et al.Endoscopic versus open vein-graft harvesting in coronary-artery bypass surgery.N Engl J Med. 2009; 361: 235-244Crossref PubMed Scopus (274) Google Scholar] study) of the appropriate reference group to test the hypothesis regarding the effect of EVH, which should have been the placebo group and not the group in which the ex vivo treatment of vein grafts with the edifoligide had been used, because this causes the auto-immune study to be biased from the effects of confounding factors and interactions. The study by Ouzounian and colleagues [4Ouzounian M. Hassan A. Buth K.J. et al.Impact of endoscopic versus open saphenous vein harvest techniques on outcomes after coronary artery bypass grafting.Ann Thorac Surg. 2010; 89: 403-409Abstract Full Text Full Text PDF PubMed Scopus (74) Google Scholar] demonstrated some paradoxical findings; for example, the clinical outcomes in the experimental group (endoscopic vein harvesting) were superior to the conventional group. Findings like this cannot be easily explained.3Adjustment for significant learning curve effects, such as sequence of cases at the surgeon level, is an important factor to assess the efficacy of new technology, and this can bias the results of the studies. Second, apart from attention to design, power, and protection from bias, it is evident that careful strategic planning for designing research agendas and being able to make sense of the overall picture of all randomized controlled trials in the cardiothoracic field is required. Designing trials in isolation or with nonscientific priorities creates fragmented, irrelevant evidence. The more difficult challenge is to dismiss false discoveries and materialize some truly useful findings. Impact of Endoscopic Versus Open Saphenous Vein Harvest Techniques on Outcomes After Coronary Artery Bypass GraftingThe Annals of Thoracic SurgeryVol. 89Issue 2PreviewEndoscopic saphenous vein harvest (EVH) decreases leg wound infections and improves cosmesis after coronary artery bypass grafting (CABG). Recent data, however, suggest that EVH may be associated with reduced graft patency rates. The objective of this study is to assess the effect of EVH on short-term and midterm outcomes after CABG. Full-Text PDF