[Flowmetric and angiographic predictors of occlusion of coronary bypass grafts]

The study was aimed at assessing remote (up to 42 months) results of coronary artery bypass grafting (CABG) and revealing flowmetric and angiographic predictors of coronary bypass graft occlusion.

Our retrospective single-centre study included a total of 141 patients undergoing coronary artery bypass grafting (CABG). All patients were subjected to assessment of coronary bypass grafts by means of transit-time flowmetry (TTFM), as well as angiographic control of coronary bypass grafts in the remote period. The duration of follow up amounted to 42 months. We performed flowmetric assessment of blood flow by the following parameters: mean volumetric blood flow velocity (Qmean), peripheral resistance (PR), as well as studied angiographic parameters such as: the degree of proximal stenosis of the bypassed coronary artery (CA), the diameter of the bypassed CA. Competence of bypass grafts after carried out coronaroshuntography (CSG) was determined according to the classification of Fitzgibbon.

We performed flowmetric and angiographic assessment of 235 autoarterial and 117 autovenous bypass grafts. During the follow-up period of up to 42 months we revealed 33 (14%) occluded arterial conduits and 30 (25.6%) venous ones. The Kaplan-Meier analysis demonstrated that the probability of the lack of occlusions of venous grafts amounted to 74.4±5.8%, with that of arterial grafts equalling 86±3.3%, i. e. during the follow-up period of up to 42 months, the probability of occlusion of venous grafts was reliably higher than that of arterial ones (Log Rank=0.006). The Cox regression analysis made it possible to reveal that occlusion of grafts was influenced by an increase in the peripheral resistance index (p=0.033, HR=1.374), a decrease of volumetric blood flow velocity in the graft (Qmean) (p=0.005; HR=0.981), and by the type of the graft (venous) (p=0.001; HR=2.587).

1) arterial grafts appeared to yield better results of myocardial revascularisation within the terms up to 42 months as compared with venous coronary artery bypass grafting; 2) using a vein increases the risk for the development of graft occlusion 2.5-fold each month after the operation; 3) an increase in the peripheral resistance index (PR) by 1 unit elevates the risk of occlusion of the coronary graft 1.3-fold with each month after the operation; 4) a decrease in the volumetric blood flow velocity (Q) by 1 ml leads to an increase in the risk of graft occlusion by 2% with each month after the operation.