Phosphodieserase-5 enzyme is activated in heart failure and can limit the beneficial effects of nitric oxide, (NO), in the vasculature, kidney and myocardium. The benefits of phosphodiesterase inhibitors are well documented in erectile dysfunction and pulmonary arterial hypertension. Although some studies with sildenafil in heart failure show reduced ejection fraction, their role in heart failure with preserved ejection fraction remains uncertain. The aim of this study was to evaluate whether long-term treatment with sildenafil improves functional capacity, (peak VO2), in patients with heart failure and preserved function.
152 patients were randomized with heart failure and preserved function in functional class II-IV, ejection fraction equal or above 50% and objective evidence of heart failure when sildenafil was taken, (n = 76), or placebo, (n = 76). The primary endpoint was improvement in peak VO2 after twenty-four weeks of treatment. There was no difference between the sildenafil group and the placebo group, (p = 0.9). There were no differences with respect to death, hospitalization, cardiovascular adverse events and cardio renal
Conclusion: Chronic treatment with sildenafil was not associated with any clinical benefit in heart failure with preserved ventricular function. More research is needed to identify the key mechanisms in heart failure with preserved function, thus helping to guide their treatment.
Margaret Redfield
2013-03-11
Original title: Phosphodiesterase-5 Inhibition to Improve Clinical Status and Exercise Capacity in Diastolic Heart Failure – RELAX Trial.
