Accordingly, the renin-angiotensin system role was investigated in many works. Indeed, angiotensin II plays a role in the modification of atrial pressure and in the fibers stretching ["stretch"], conditions required for the development of AFib. Angiotensin II is also a factor implied in the tissue fibrosis leading to tissue proliferation and collagen alteration. These mechanisms lead to atria cells conduction disorders and refractory periods modification. Moreover, the enzyme of conversion expression and the angiotensin II receptors deterioration were observed in patients with AFib.