J Thorac Cardiovasc Surg 2008;136:238-239
© 2008 The American Association for Thoracic Surgery
Reply to the Editor:
Robert Poston, MD
Department of Surgery, University of Maryland School of Medicine, Baltimore, Md
A small single-center study cannot provide definitive answers to any of the important questions posed by Dr Gulbins. We agree that our data do not support the conclusion that the hybrid approach is superior to the off-pump coronary artery bypass (OPCAB) procedure. An important goal of this article is merely to provoke debate about how innovations such as this might be used to improve the results for surgical revascularization.
There is no question that differences in clinical outcomes between the 2 groups were driven by variables other than the use of a small thoracotomy instead of a median sternotomy. For example, differences in the choice of conduits undoubtedly influenced outcome. A key advantage of the hybrid procedure is the use of percutaneous coronary intervention/stenting as a means of avoiding the well-known shortcomings of saphenous vein grafts that is used in more than 95% of coronary artery bypass grafting procedures done through a sternotomy. Computed tomographic angiographic follow-up is not adequate to detect in-stent restenosis, but the use of coated stents according to the entry criteria of our study minimized the expected risk of this problem to less than 10% in our cohort.1
The risk of thrombosis is increased with these types of stents, but thrombosis has a dramatic presentation that can be reliably diagnosed by clinical means. Therefore the advantages provided by the use of invasive angiography instead of computed tomographic angiography for investigating the benefits of using stents versus the saphenous vein graft in our cohort would have been modest.
We agree that the blood loss in the OPCAB group was higher than has been reported by other groups. This might have reflected a more rigorous assessment of intraoperative losses, including the volume of blood retrieved by the cell saver; weighing of sponges; and estimation of other losses. It also might reflect a higher-risk population of patients than have been enrolled in prior OPCAB analyses. Nonetheless, the blood loss and rate of transfusions for the minimally invasive group was clearly less than has been reported in most other OPCAB reports.2
Finally, we agree that OPCAB does not require occlusion of coronary arteries during each anastomosis but disagree that the routine insertion of a shunt is the standard by which most cardiac centers practice OPCAB. There are concerns about the risk of coronary injury with the insertion of a shunt,3 particularly in the population of patients referred for coronary artery bypass grafting with poor-quality targets. Because this injury might also provoke regional inflammation and thrombosis, we have used shunts selectively for those with evidence of ischemia after brief coronary occlusion. Admittedly, this is an area that requires further analysis.
References
- Van Belle E, Susen S, Jude B, Bertrand ME. Drug-eluting stents: trading restenosis for thrombosis?. J Thromb Haemost 2007;5(suppl 1):238-245.[Medline]
- Raja SG, Dreyfus GD. Impact of off-pump coronary artery bypass surgery on postoperative bleeding: current best available evidence. J Card Surg 2006;21:35-41.[Medline]
- Dygert JH, Thatte HS, Kumbhani DJ, Najjar SF, Treanor PR, Khuri SF. Intracoronary shunt-induced endothelial cell damage in porcine heart. J Surg Res 2006;131:168-174.[Medline]
