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Does competitive flow reduce internal thoracic artery graft patency?
Joseph F Sabik1, Bruce W Lytle, Eugene H Blackstone
1Department of Thoracic and Cardiovascular Surgery, The Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA. sabikj@ccf.org
Insights
Internal thoracic artery (ITA) graft patency decreases with increased coronary competitive flow. However, moderate stenosis does not necessitate abandoning ITA use in coronary artery bypass grafting (CABG).
Area of Science:
- Cardiovascular Surgery
- Vascular Biology
- Graft Patency Research
Background:
- Competitive flow in coronary arteries with moderate stenosis can lead to internal thoracic artery (ITA) graft occlusion.
- Understanding the relationship between stenosis severity and ITA patency is crucial for surgical decision-making.
Purpose of the Study:
- To determine if competitive flow negatively impacts ITA graft patency.
- To identify a specific degree of coronary stenosis below which ITA use might be inadvisable.
Main Methods:
- Analysis of 2,121 ITA grafts from 50,278 patients undergoing coronary artery bypass grafting (CABG) between 1972 and 1999.
- Longitudinal analysis to model time-related ITA occlusion and identify risk factors, using proximal coronary stenosis as a surrogate for competitive flow.
Main Results:
- Overall ITA patency rates were high (93% at 1 year, declining to 92% at 15 years).
- Lesser degrees of proximal coronary stenosis were significantly associated with increased ITA occlusion risk (p < 0.0001).
- ITA patency declined as stenosis severity decreased, but without a sharp drop-off at any specific stenosis grade.
Conclusions:
- Internal thoracic artery (ITA) graft patency is inversely related to the degree of coronary competitive flow.
- Despite the association, moderate grades of coronary stenosis should not be an absolute contraindication for ITA graft utilization.
Background:
In coronary arteries with moderate stenosis, competitive flow may lead to internal thoracic artery (ITA) graft occlusion. The goals of this study were to determine if competitive flow reduces ITA patency, and if there is a degree of coronary stenosis below which ITAs should not be used.
Methods:
From 1972 to 1999, 50,278 patients underwent primary coronary artery bypass grafting (CABG). Of these, 2,002 had at least one ITA graft and postoperative angiography before coronary reintervention; 2,999 angiograms of 2,121 ITAs were made. Time-related ITA occlusion was modeled using longitudinal analysis to identify its risk factors while accounting for lack of independence introduced by repeated angiography and multiple ITA anastomoses per patient. Proximal coronary stenosis (maximum preoperative stenosis between ITA anastomosis and aorta) was the surrogate for competitive flow.
Results:
Unadjusted ITA patency was 93%, 89%, 90%, and 92% at 1, 5, 10, and 15 years after CABG. Risk factors associated with ITA occlusion were lesser degree of proximal coronary stenosis (p < 0.0001); longer time from CABG in grafts to non-left anterior descending coronary arteries (p < 0.0001); female sex (p = 0.0003); later date of CABG (p = 0.01); right ITA (p < 0.0001); and smoking (p < 0.0001). In all arteries, as preoperative proximal coronary stenosis decreased, ITA patency declined; however, at no degree of stenosis was there a sharp decline.
Conclusions:
Internal thoracic artery patency decreases as coronary competitive flow increases. However, the nature of this relationship indicates ITAs should not be abandoned at moderate grades of stenosis.
