Early silent graft failure in off-pump coronary artery bypass grafting: a computed tomography analysis†

Abstract

Objectives: The purpose was to assess predictors of early silent graft failure prior to discharge by multislice computed tomography in patients after off-pump coronary artery bypass grafting.

Methods: From January 2017 until April 2018, 192 computed tomographic scans of consecutive asymptomatic patients were performed (seventh postoperative day ± 4 days) and analysed retrospectively. In total, 359 arterial and 278 venous anastomoses were evaluated. Two patient groups (overall patent anastomoses versus at least 1 occluded anastomosis) were compared. Cardiovascular risk factors, collateralization according to Rentrop, grade of native vessel stenosis and intraoperative flow measurements were analysed. Inferential statistics were performed with the Mann-Whitney U-test. Nominal and categorical variables were tested with the Fisher-Freeman-Halton exact test.

Results: In 33 patients, at least 1 occluded anastomosis could be identified, predominantly in women (P = 0.04). The patency of the arterial anastomoses was 96.4% and 88.9% for the venous anastomoses. In 14 patients with occluded anastomoses, a successful interventional revascularization was performed before discharge. There were significant differences in lower bypass flow [P = 0.02, odds ratio 3.2, 95% confidence interval (CI) 1.7-6.0] and higher pulsatility index (P < 0.001, odds ratio 4.5, 95% CI 2.4-8.5) in the occluded group. A calculated cut-off value identified an increased probability for graft occlusion at a flow under 23 ml/min and a pulsatility index greater than 2.3.

Conclusions: Early silent graft failure occurred predominantly in venous grafts, with a tendency to female gender. A lower flow rate and a higher pulsatility index were significantly associated with graft occlusion, whereas collateralization and the degree of native vessel stenosis seem to play a tangential role. Fourteen patients had a successful percutaneous revascularization before discharge.

Clinical trial registration number: NCT03657199.

Keywords: Bypass failure; Bypass occlusion; Graft patency; Off-pump coronary artery bypass grafting; Pulsatility index; Transit flow measurement.