The Investigator-Coordinator has moved to Rennes University Hospital. It will be done under the sponsor of Rennes University Hospital : NCT03686306

Peripheral Arterial Disease (PAD) is a highly debilitating disease that affects 202 million people around the world and about 7 million people in France. Morbi-mortality from cardiovascular events is increased in this population. Intermittent claudication is the most common clinical feature of PAD.

Primary therapeutic approach is medical treatment and advice to walk. Sildenafil, a PDEi type 5, is well tolerated, largely used in impotence and has interesting clinical delay and duration of action in the concept of a potential use in claudication.

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).

Inclusion Criteria:

• Grade I cat 2 or 3 claudication despite optimal medical treatment
• Reporting a vascular claudication history for at least 3 months
• Able to achieve a walking treadmill test, Walking time on treadmill (3.2km/h, 10% slope) less than 5 minutes
• Having no cons Sildenafil indication
• Must be on optimal medical therapy (ACE Inhibitors / AT2 Antagonist + Antiplatelet + Lipid Lowering drugs) for at least 1 month

Exclusion Criteria:

• Critical ischemia
• Previous history of myocardial infarction or angina not stabilized
• Amblyopia
• Treated with nitrates (nitroglycerin ...) or drugs interfering with the action of the Sildenafil
• Pregnant woman and woman in labor
• Major Person subject to reinforced protection, deprived of their liberty by judicial or administrative decision, hospitalized without consent or admitted to a health or social establishment for purposes other than research
• Being in an exclusion period for another biomedical study