Endoscopic vein-graft harvesting was not associated with increased rates of death, myocardial infarction, or repeat revascularization in patients undergoing coronary artery bypass grafting, according to a database analysis of more than 200,000 patients. The study was requested and funded by the Food and Drug Administration and reported in the Aug. 1 issue of JAMA.
In 2009, an observational study of 3,000 CABG patients showed that endoscopic vein-graft harvesting carried a higher risk of mortality and graft failure than did open vein-graft harvesting. It was suggested that the endoscopic technique might cause more harm because it involved added vessel manipulation, venous stasis from the pressurized subcutaneous tunnel, and larger caliber vein-graft segments. In addition, other studies throughout the world showed conflicting results when comparing the two techniques.
In response, the FDA asked that the issue be further investigated using the massive Society of Thoracic Surgeons’ adult cardiac surgery database. By linking this information with data on long-term outcomes from the Centers for Medicare and Medicaid Services database, investigators were able to track outcomes in 235,394 patients who underwent primary isolated CABG at 934 sites during a 5-year period. They were followed for a median of 3 years.
Dr. Judson B. Williams of Duke Clinical Research Institute, Durham, N.C., and his associates found no significant difference between the two techniques of vein-graft harvesting in overall mortality. The cumulative rates of death were 13.2% in the 122,899 patients who had endoscopic vein-graft harvesting and 13.4% in the 112,495 who had open vein-graft harvesting.
In addition, the composite rate of death, MI, or repeat revascularization also was not significantly different between the two groups: 19.5% with endoscopic and 19.7% with open vein-graft harvesting, the investigators said (JAMA 2012;308:475-84).
The endoscopic technique carried a significantly lower rate of harvest site wound complications, as expected (3.0% vs. 3.6%).
The large study population allowed for further assessment of important subgroups of CABG patients. Again, there were no differences in outcomes between endoscopic and open techniques in the nearly 42,000 subjects with insulin-dependent diabetes, and no differences according to subjects’ body mass index. There also were no differences in outcomes according to the number of vein-grafts harvested.
The results of sensitivity analyses paralleled the main finding of the study. CABG patients undergoing endoscopic vein-graft harvesting showed the same long-term mortality and the same composite rate of death, MI, and revascularization as did those undergoing open vein-graft harvesting, but significantly lower rates of wound complications.
As with other studies of this controversial issue, this analysis was limited in that it "was unable to account for differences in conduit caliber between the endoscopic and open vein-graft harvesting groups, a potentially critical confounding variable" in comparing the two techniques, Dr. Williams and his associates said.
Another important limitation was the length of follow-up – only 3-years, since the STS database did not identify endoscopic harvesting before 2008.
In addition, "our observational study, as with previous studies, is unable to assess for particulars of technique such as carbon dioxide insufflations, use of electrocautery, or the experience of the endoscopic harvester," they added.
This study was funded by the Food and Drug Administration, the National Institutes of Health, and the National Heart, Lung, and Blood Institute. Dr. Williams reported no financial conflicts of interest, and his associates reported numerous ties to industry sources.