Venous But Not Arterial Graft Failure Associated with Ischaemic Sequelae After Coronary Bypass Surgery

Late survival after coronary artery bypass grafting may depend not only on patency of the graft but also on patency of the proximal coronary lesion in the event of graft failure. Reduced proximal coronary patency following graft failure may be associated with ischaemic sequelae, potentially affecting postoperative survival. Arterial and venous conduits follow distinct mechanisms of failure, and the postoperative patency status of the proximal coronary stenosis has not been widely considered in this context.

Patients underwent predominantly symptom-indicated coronary angiography between August 1997 and March 2020, following coronary artery bypass grafting. Patients with greater than or equal to one angiographically occluded graft distal to a coronary lesion that was patent at surgery, were primarily analysed. For each occluded graft, the coronary lesion proximal to the anastomosis was assessed for preservation of patency on postoperative angiography. The occurrence of non-fatal non-ST-segment elevation myocardial infarction (NSTEMI) in symptomatic patients undergoing postoperative angiography, with and without graft failure, was evaluated in a secondary analysis. Primary graft-level outcomes were analysed using exchangeable Generalised Estimating Equations binary logistic regression, and secondary patient-level outcomes were analysed using binary logistic regression.

Overall, 145 patients were included in the primary analysis, with a mean follow-up of 9.2±5.6 years after surgery. Native coronary patency was 100% at surgery, with a similar degree of stenosis proximal to occluded arterial conduits and saphenous vein grafts (SVGs), 68.2±16.5% vs 72.2±15.7%, respectively, (p=0.216). At postoperative angiography, proximal coronary patency was more frequently preserved with occluded arterial grafts than with occluded SVGs, 83.1% (133/160) vs 38.7% (12/31) (odds ratio [OR] 4.96; 95% confidence interval [CI] 1.91-12.89; p=0.001). Among 179 symptomatic patients in the secondary analysis with greater than or equal to one SVG, NSTEMI occurred more frequently in those with SVG failure than in those without SVG failure, 42.2% vs 17.9% (OR 3.35; 95% CI 1.60-7.01; p=0.001). Among 563 symptomatic patients who underwent total arterial revascularisation, the frequency of NSTEMI was similar in those with and without arterial graft failure, 20.8% vs 24.4% (OR=0.81, 95% CI 0.52-1.27; p=0.360).

Venous, but not arterial, graft failure is associated with reduced proximal coronary lesion patency, which may contribute to ischaemic sequelae.