For patients agreeing and signing informed consent, randomisation of treatment (placebo/sildenafil) will be done. Treatment will be proposed in addition to usual treatment. The experimental drug will be delivered for a 1 month treatment. First follow up visit at month one will focus on tolerance, compliance and eventual side effects. If no major side effect is found the study drug will then be delivered for an additional 2 months. Patients will be evaluated at month 3 (second follow-up visit) for persistent or non-persistent indication for revascularisation and addressed for revascularization if needed. In parallel focus on tolerance, compliance and eventual side effects will be done. If no major side effect is found, the study drug will be delivered for an additional 3 months treatment. Third and fourth follow-up visit are scheduled at month 6 (end of treatment) and month 9 (3 months after the end of experimental drugs).