Surgical Revascularization of Chronically Occluded Coronary Arteries: What You See Is What You Get?

In CABG surgery, revascularization strategy usually depends on coronary dimension and stenosis severity. However, little is known about the relation of preoperative evaluation of scarce or invisible CTOs and revascularization rates or anastomosis quality. Therefore, we aimed to evaluate the success rates of CTO revascularization in CAGB surgery and determined the influence of coronary lumen visibility and collateralization in preoperative angiograms on revascularization rates, bypass blood flow and target vessel diameter. We analyzed 490 consecutive patients that underwent isolated CABG surgery in 2015 and 2016. All preoperative coronary angiograms were evaluated and screened for occluded vessels. The occluded vessels were scored for visibility using the Rentrop grading of collateral filling. The CABG quality was assessed intraoperatively by transit-time flow measurement. 213 (43.5%) Patients were identified with CTO of at least one coronary artery. Of these, 38 (17.8%) had more than one CTO. 55 Patients had an occluded LAD (25.8%), in 69 (32.4%) and 127 (59.6%) RCX, RCA or one of their branches respectively was affected. 39 (18.3%) patients had previous PCI of which 9 (4.2%) had stents implanted in the occluded vessel. In 171 (80.3%) patients all CTOs were revascularized. In patients with an occluded LAD (arterial grafts), RCX or RCA (venous grafts) the vessels were revascularized in 49 (89.1%), 56 (81.2%) and 111 (87.4%) patients respectively. Lower Rentrop scores where not associated with impaired mean bypass flow in LAD and RCX territory (LAD: p = 0.47, RCX: p = 0.554). There was a trend toward better blood flow in venous grafts revascularizing the RCA or its branches (p = 0.0341) with increased lumen visibility in the preoperative assessment. However, this difference was not confirmed by post-hoc testing. Not or scarcely visible CTO target vessels had similar revascularization rates compared with well visible arteries (p = 0.891). Furthermore, grade of visibility had no effect on vessel diameter (LAD: p = 0.844, RCX: p = 0.24, RCA: p = 0.239). Preoperative coronary assessment of CTOs by visibility might be misleading and often differs from intraoperative findings. Our study confirms that patients have a high chance of complete revascularization during CABG surgery even if preoperative assessment reveals scarcely collateralized CTOs with impaired visibility.