Natural history of infrainguinal vein bypass stenoses: early lesions increase the risk of thrombosis.

OBJECTIVES To describe the natural history of stenoses in infrainguinal vein bypasses and to identify factors predicting outcome. METHODS Forty-two patients with non-revised vein bypass stenoses were followed prospectively by ultrasound Duplex scanning and ankle blood pressure measurements. RESULTS During a median follow-up of 8 (range 0-22) months 18 (43%) (95% confidence limits 28-59%) bypasses thrombosed and 6 (14%) (95% confidence limits 5-29%) patients were amputated. Bypass patency was lower in 12 patients with stenoses associated with reduction in ankle brachial index (ABI) exceeding 0.15 than in 30 patients with no or only marginal reduction in ABI (12 month patency 33% vs. 68%, p = 0.005). Among the 30 patients without distal pressure reduction, stenoses identified within 3 months from surgery were associated with an increased risk of thrombosis as compared to stenoses identified at a later stage (12 month patency 51% vs. 92%, p = 0.03). CONCLUSION Time interval from surgery to stenosis detection seems to be an independent parameter influencing outcome in patients with vein bypass stenoses.