Phosphodiesterase-5 Inhibitor (Tadalafil) Two Weeks Administration Period Effects in Left Ventricle Diastolic Dysfunction and BNP Levels in Resistant Hypertensive Patients

Resistant hypertensive patients have a high incidence of left ventricle diastolic dysfunction (LVDD). Lowering blood pressure levels improves diastolic function, however, there is no proved effective treatment specifically for this disease. Studies in hypertensive rats have shown presence of phosphodiesterase-5 in cardiac cells and an improvement in left ventricle diastolic function using a phosphodiesterase-5 (PDE5) inhibitor, the sildenafil. PDE5 has also been demonstrated in human heart cells with cardiac disease. In addition, LVDD is associated with high levels of brain natriuretic peptide (BNP), which reduces with diastolic function improvement. Therefore, it is reasonable to suppose that PDE-5 inhibitor use in humans with LVDD and resistant hypertension could improve diastolic function. Objective: Evaluate the chronic effect of a PDE-5 inhibitor on LVDD and BNP levels in resistant hypertensive patients. Casuistic and methods: 20 resistant hypertensive patients with LVDD types I and II will be evaluated with echocardiography study, ambulatory blood pressure monitoring (ABPM), office blood pressure measurements, endothelial function analysis using the brachial artery flow mediation dilation technique (FMD) and BNP plasma levels. Then, the subjects will receive oral placebo for 2 weeks. After this period, the same exams will be repeated. Two weeks later, the protocol will be performed again to the same 20 patients, using tadalafil (the longest half-life PDE-5 inhibitor) 20mg orally instead of the placebo. Hypothesis: investigators hypothesize that the use of tadalafil will improve left ventricle diastolic function with BNP reduced levels and this effect will be independent of blood pressure decrease or endothelial function improvement.