Occluded infrainguinal grafts: when to choose lytic therapy versus a new bypass graft

The published results of thrombolysis for occluded bypass grafts, including a prospective multicenter trial, have been disappointing, prompting many investigators to proceed directly to a new bypass rather than attempt graft salvage. Our series of 61 occluded grafts treated with lytic therapy, however, identified a subgroup that justified attempted graft salvage.

The grafts consisted of saphenous vein 59% (36/61), other vein (arm or composite vein) 21% (13/61), and polytetrafluoroethylene (PTFE) 29% (13/61). The data analysis was designed to identify the graft subgroup that would benefit from lytic therapy by using cumulative survival analysis techniques with the Wilcoxon (Gehan) test for univariate analysis and Cox proportional hazards model for multivariate analysis. Specific variables examined by univariate analysis were graft age (defined as the interval from initial bypass to graft lysis), graft material, graft type (femoropopliteal versus femorotibial), diabetes, symptoms (claudication versus salvage) and duration of occlusion prior to lysis.

Complete lysis was achieved in 72% (44/61) of the grafts, and 86% (38/44) had an underlying stenosis that was treated by percutaneous balloon angioplasty (28/38) or surgery (7/38). Three stenotic outflow lesions were not treated. Cumulative 5-year patency for all 61 grafts was 23% +/- 0.075 (SE). Only graft age < 10 versus > 10 months was significant (P < 0.004) by univariate analysis, and it was also the only significant variable found by multivariate analysis; it indicated a 1.58 increase in relative risk of occlusion for the younger grafts. The combination of a saphenous vein graft that was also > 10 months old resulted in a 45% 5-year patency, compared to 21% for < 10-month-old saphenous vein grafts (P < 0.008). A review of 161 bypass grafts performed at our institution over the past 10 years revealed a 52% 5-year secondary patency in previously bypassed limbs, which varied with graft material (67% saphenous, 50% alternative vein, 31% prosthetic). Lysed graft patency was comparable to that of a second bypass using other veins or PTFE conduit.

In the absence of an intact saphenous vein for a second bypass, thrombolytic therapy is an alternative to surgery.