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In contrast to the large body of information regarding graft patency, data regarding atherosclerosis progression and vessel patency in surgically bypassed native coronary arteries are less clear. We aimed to determine native coronary artery patency one year after CABG, and to identify clinical and angiographic predictors for developing a chronic total occlusion (CTO).
Included in our study were 388 patients who underwent 1-year follow-up angiography as part of the multi-centre Radial Artery Patency Study (RAPS). Angiograms were reviewed for native coronary artery patency in an independent blinded manner.
In the pre-operative angiogram, CTO of at least one native coronary vessel was demonstrated in 240 (61.9%) patients having 305 occluded vessels. At 1 year post CABG, at least 1 new native coronary artery CTO occurred in 169 (43.6%) patients. In 7.5% of patients, the native artery and the graft supplying that territory were both occluded. A new CTO was almost five times more likely to occur in coronary vessels with a pre-operative proximal stenosis >90% compared to vessels with proximal stenosis <90% (45.5% versus 9.5% respectively, p<0.001). Patients with a new CTO had significantly more baseline CCS class 4 angina, and higher creatinine levels compared to patients without a new CTO. A new CTO was less likely to occur in the LAD (18.4%), supplied by the LITA. When comparing radial artery and SVGs, neither the type of graft nor graft patency had any association with native coronary artery occlusion.
CTO of surgically bypassed coronary arteries 1 year following CABG is extremely common, suggesting accelerated progression of atherosclerosis in these vessels.