Endoscopic versus Open Harvesting of Saphenous Vein Grafts: Secondary PREVENT IV analysis published in New England Journal of Medicine
July 16, 2009: Among patients undergoing coronary artery bypass surgery (CABG), endoscopic vein-graft harvesting was associated with higher rates of vein graft failure and adverse clinical outcomes than direct-vision open harvesting, according to an article published today in the New England Journal of Medicine.
The use of endoscopic harvesting has been associated with reduced pain and improved cosmetic results in previous randomized trials  when compared to the more traditional open harvesting method, whereby veins are excavated by a series of incisions under direct vision.  In order to assess the long term results of these harvesting strategies, investigators analyzed data from the PREVENT IV (Project of Ex-vivo Vein Graft Engineering via Transfection IV) Trial, a phase III, multicenter, double-blind, placebo controlled trial of 3014 CABG patients investigating the efficacy of graft pretreatment with edifoligide.   For this secondary analysis, angiographic data 12 to 18 months post-surgery were available for 822 patients who underwent open harvesting (involving 1969 grafts) and 995 patients  who underwent the endoscopic procedure (involving 2321 grafts) with 3 year follow-up event data available for 1247 and 1753 patients undergoing  open and endoscopic harvesting respectively.  The primary angiographic outcome was vein-graft failure (defined as stenosis >=75% the graft diameter as determined by an independent blinded core laboratory), and the primary clinical outcome measure was the composite of death, myocardial infarction, and repeat revascularization.
Compared to open harvesting, endoscopic harvesting was associated with higher rates of vein-graft failure when analyzed by patient (46.7% vs 38.0%; odds ratio 1.45 ; p<0.001) or by graft (27.2% vs 22.6%; odds ratio:1.34 ; p<0.001).  The endoscopic strategy was also associated with a higher Kaplan-Meier estimate of the 3 year event rate of the primary clinical outcome measure (20.2%  vs 17.4%  for the open harvesting cohort; adjusted hazard ratio: 1.22 ; p=0.04).
The investigators noted that their study was not randomized and although the model was adjusted for weight, duration of surgery, worst graft quality, worst target-artery quality, and use of composite or non-composite grafts, other potential cofounders could exist.  Additionally, PREVENT IV investigators did not collect measures of surgical experience or what type of device was used for the endoscopic harvesting procedure, and could therefore not determine whether differences in operator technique or device may have influenced their results.
The findings of this secondary PREVENT IV analysis suggest that despite the recognized short-term benefits of the endoscopic method of saphenous vein graft harvesting (lower rates of infection and pain,  shorter hospital stays and improved cosmetic results), the high rates of vein-graft failure and rates of death, myocardial infarction and revascularization must be considered for patients undergoing coronary artery bypass surgery.  Future randomized studies will be required to further investigate the effects of varying harvesting techniques.