Influence of smoking and plasma factors on patency of femoropopliteal vein grafts

Abstract

Objective - To determine the effects of smoking, plasma lipids, lipoproteins, apolipoproteins, and fibrinogen on the patency of saphenous vein femoropopliteal bypass grafts at one year. Design - Prospective study of patients with saphenous vein femoropopliteal bypass grafts entered into a multicentre trial. Setting - Surgical wards, outpatient clinics, and home visits coordinated by two tertiary referral centres in London and Birmingham. Patients - 157 Patients (mean age 66.6 (SD 8.2) years), 113 with patent grafts and 44 with occluded grafts one year after bypass. Main outcome measure - Cumulative percentage patency at one year. Results - Markers for smoking (blood carboxyhaemoglobin concentration (p < 0.05) and plasma thiocyanate concentration (p < 0.01) and plasma concentrations of fibrinogen (p < 0.001) and apolipoproteins AI (p < 0.04) and (a) (p < 0.05) were significantly higher in patients with occluded grafts. Serum cholesterol concentrations were significantly higher in patients with grafts that remained patent one year after bypass (p < 0.005). Analysis of the smoking markers indicated that a quarter of patients (40) were untruthful in their claims to have stopped smoking. Based on smoking markers, patency of grafts in smokers was significantly lower at one year by life table analysis than in non-smokers (63% v 84%, p < 0.02). Patency was significantly higher by life table analysis in patients with a plasma fibrinogen concentration below the median than in those with a concentration above (90% v 57%, p < 0.0002). Surprisingly, increased plasma low density lipoprotein cholesterol concentration was significantly associated with improved patency at one year (85%) at values above the median compared with patency (only 68%) at values in the lower half of the range (p < 0.02). Conclusions - Plasma fibrinogen concentration was the most important variable predicting graft occlusion, followed by smoking markers. A more forceful approach is needed to stop patients smoking; therapeutic measures to improve patency of vein grafts should focus on decreasing plasma fibrinogen concentration rather than serum cholesterol concentration.