Increasing Long-Term Major Vascular Events and Resource Consumption in Patients Receiving Off-Pump Coronary Artery Bypass. A Single-Center Prospective Observational Study
Hu S, Zheng, Z, Yuan X, et al.
Circulation 2010 Apr 27;121(16):1800-8.
Reviewer: Mohammed Minhaj, MD
University of Chicago Medical Center, Chicago, IL
This was a retrospective review of prospectively gathered data of 6665 patients undergoing isolated coronary artery bypass grafting (CABG) between 1999-2006. The purpose was to determine the long-term outcomes and cost-effectiveness of off-pump CABG (OPCABG). Short- and long-term outcomes were compared between OPCABG and conventional CABG (cCABG) and the two principal outcomes studied were repeat revascularization and major vascular events (MVE). The investigators also compared costs associated with the two approaches, both in-hospital costs and overall costs. Patients who underwent OPCABG were less likely to have atrial fibrillation, requirements for blood transfusions, and prolonged mechanical ventilation (> 24 hours) when compared to cCABG. During the follow-up period, the rates of repeat revascularization and MVEs were significantly higher in the OPCABG than the cCABG group. OPCABG patients also had higher directs costs per patient compared with cCABG at 2 years and had a similar survival rate. The authors concluded that when compared to cCABG, OPCABG was associated with small short-term gain but increased long-term risks of repeat revascularization and MVEs and consumed more resources and was less cost-effective over time.
There are several important points to consider when reading this article as it has several strengths. These include: a large number of patients, a prospective design, and great long-term follow-up of patients enrolled in the trial. Furthermore, it was interesting that in China (where the study was performed), that currently ~70% of CABG procedures are done utilizing an off-pump (OPCABG) approach. Over the time period of the study, the rates of OPCABG increased dramatically, but it should be noted that there was no significant differences in long-term outcomes when patients were compared by subgroups divided by year of surgery. However, surgeons who had performed > 300 OPCABG procedures had the lowest event rate, which has been supported by other studies suggesting that greater experience with this approach yields better results.
The authors’ findings that OPCABG was associated with increased rates of revascularization when compared to cCABG are also consistent with previous studies. However, there have not been large studies examining long-term effects of OPCABG on major vascular events (MVEs) such as stroke, myocardial infarction, etc. Additionally, there have not been long-term cost comparisons between cCABG and OPCABG. Both of those were examined in this paper and the results were not favorable for OPCABG.
While in-hospital costs associated with OPCABG were less than those compared with cCABG, the worse long-term outcomes in particular the increased risk of MVEs led to significantly greater costs. These MVEs were even more likely in higher risk patients (elderly, three-vessel disease, or with abnormal renal function). Additionally, patients with incomplete revascularization did significantly worse with respect to the development of MVEs.
As impressive as the results are, the study did have some limitations. While the data was prospectively gathered, the patients were not randomized. The authors also commented on the fact that they did not do angiographic studies as part of the routine long-term follow-up. While looking at MVEs, rates of revascularization and costs may be seen as surrogates of decreased graft flow in OPCABG, graft quality remains an area of interest in the study of OPCABG.
Overall the study’s results provide even greater data about the long-term outcomes associated with OPCABG with the added information regarding costs associated with this procedure. While the rate of OPCABG has seemingly plateaued in Western countries as a result of questionable long-term benefit, it will be interesting to see if this study’s results will impact the rates of OPCABG in China and elsewhere.