Long-term surveillance by duplex scanning of nonrevised infragenicular graft stenosis.
To define the prognosis of nonrevised graft stenosis, we studied 68 infragenicular bypass grafts in patients entered into our duplex surveillance program between 1986 and 1987. Patients were grouped according to the grade of stenosis as follows: grade I = < 50% stenosis, grade II = 50% to 75% stenosis, and grade III = 75% to 99% stenosis. Time until maximum stenosis was stratified into three intervals (< 3 months, between 3 and 12 months, and > 12 months). Cumulative patency rates from the time of maximum stenosis to failure were calculated using Kaplan-Meier analysis. Fifty-three grafts (78%) developed stenoses: 10 with grade I, 25 with grade II, and 18 with grade III stenosis. Eighty-nine percent of the 18 graft occlusions occurred within 2 years. Two grafts occluded after 2 years without any severe stenosis or preceding clinical signs. During follow-up 15 nonrevised stenosed grafts (four with grade I, five with grade II, and six with grade III stenosis) remained patent longer than 2 years with a mean follow-up of 72 months. Statistical analysis for graft failure determined that grade II to III stenoses led to graft occlusion significantly earlier than grade 0 to I stenoses (p = 0.017). If graft failures resulting from revision were separated from the analysis, the time interval from operation to maximum stenosis (within 1 year) remained marginally significant for predicting occlusion, whereas no correlation was found between the grade of maximum stenosis and occlusion. Thus the prognosis for graft stenosis depends on the grade of stenosis and on the time interval from operation to stenosis. Therefore duplex surveillance seems to be most important within the first 24 months only, but is of little use in predicting impending graft failure beyond 2 years in asymptomatic patients.