Relationship Between Vein Graft Failure and Subsequent Clinical Outcomes Following Coronary Artery Bypass Surgery
What is the relationship between vein graft failure (VGF), assessed by coronary angiography 12-18 months post-coronary artery bypass graft (CABG) surgery, and subsequent clinical outcomes?
Using the PREVENT IV trial database, investigators studied data from 1,829 patients who underwent CABG surgery and had an angiogram performed up to 18 months following surgery. The main outcome measure was death, myocardial infarction (MI), and repeat revascularization through 4 years following angiography. To determine whether the number of vein grafts that fail is associated with worse outcomes, Cox proportional hazards models for each of the three composite endpoints were developed, each containing two covariates—number of vein grafts implanted and proportion of vein grafts that failed.
VGF occurred in 787 of 1,829 patients (43%). Clinical follow-up was completed in 97% of patients with angiographic follow-up. The composite of death, MI, or revascularization occurred more frequently among patients who had any VGF compared with those who had none (adjusted hazard ratio [HR], 1.58; 95% confidence interval [CI], 1.21-2.06; p = 0.008). This was due mainly to more frequent revascularization with no differences in death (adjusted HR, 1.04; 95% CI, 0.71-1.52; p = 0.85) or death or MI (adjusted HR, 1.08; 95% CI, 0.77-1.53; p = 0.65).
The authors concluded that VGF is common after CABG surgery and is associated with repeat revascularization, but not with death and/or MI.
In this study, VGF, assessed by angiography 12-18 months following CABG surgery, was strongly associated with an increased risk for the composite of death, MI, or repeat revascularization at 4 years following the angiogram. This relationship was mostly driven by repeat revascularization with no differences in either death or the composite of death and MI between patients with and without VGF. The high VGF rate and its relationship with worse clinical outcomes calls for more research, on how to improve both short- and long-term vein graft patency, including more optimal identification of targets based on both anatomic and functional characteristics and elucidation of the ideal medical regimen following CABG surgery to maintain vein graft patency.
Keywords: Myocardial Infarction, Proportional Hazards Models, Coronary Angiography, Coronary Artery Bypass
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