This study assessed the effectiveness and safety of bosentan when administered to thromboangiitis obliterans (Buerger's disease)patients. A clinical pilot study was designed,included in which patients with ulcer and/or pain at rest were treated with bosentan p.o at a dose of 62,5 mg twice daily during the first month, which each thereafter uptitrated to 125 mg twice daily. Study endpoints were clinical improvement rate, major or minor amputation rate, hemodynamic changes, changes in endothelial function and angiographic changes.

12 patients were included were current smokers. With bosentan treatment, no new ischemic lesions were observed in all but one patient. Overall, clinical improvement was observed in 12 of the 13 extremities (92%). Only two of 13 extremities underwent amputation after bosentan treatment. As assessed by digital arteriography with subtraction or angio-magnetic resonance image an increase of distal flow was observed in 10 out of the 12 patients. All patients experienced a statistically significant improvement in their BAFMD values (means:1.8 at baseline;6.6 at the end of the treatment;12.7 three months after the end of the treatment;p<0.01). In conclusion: Bosentan treatment may result in an improvement of clinical, angiographic, hemodynamic and endothelial function outcome. Bosentan deserves further investigation in the management TAO patients.

Inclusion Criteria:

• Critical ischemia in any extremity, causing pain at rest or non-healing ischemic ulcers, present for at least four weeks with no evidence of improvement in response to conventional treatment.

Exclusion Criteria:

• Being candidates for surgical or endovascular revascularisation of the extremity studied.

Patients suffering from Buerger's disease