Sildenafil’s Effect on Right Ventricular Function in PH-Related Heart Failure Insignificant, Study Shows

A recent study published in the journal PLoS One found that a single dose of Sildenafil is not associated with clinical improvement of right ventricular (RV) function as measured by cardiovascular magnetic resonance (CMR) in patients with PH-related heart failure (HF).

Heart failure (HF) is a complex syndrome that involves morphologic and functional alterations in both the right and left ventricular apparatus. There is a lack of knowledge regarding RV impairment and its treatment in patients with the syndrome. Among the causes of RV impairment in HF, pulmonary hypertension secondary to left sided dysfunction represents the main pathophysiological mechanism. Phosphodiesterase 5 (PDE5) inhibitors, including Sildenafil, are considered the primary treatment option for various forms of pulmonary hypertension due to their vasodilator effects on pulmonary vasculature.

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As well as the indirect effects on RV, PDE5 inhibition may improve the RV function of HF patients through direct mechanisms. Previous studies have demonstrated that PDE5 inhibition is associated with RV functional and geometrical improvement in patients with primary pulmonary hypertension, however, studies on patients with HF have revealed mixed results.

Background Terminology

• Phosphodiesterase 5 (PDE5) inhibitors: A drug approved  by the US Food and Drug Administration (FDA) that has been shown to be effective in a broad population of men with Erectile Dysfunction, including patients with vascular disease, coronary artery disease, hypertension, and diabetes.
• Cardiovascular Magnetic Resonance: A non-invasive test that creates detailed pictures of organs and tissues. “Noninvasive” means that no surgery is done and no instruments are inserted into the body.

In order to test the impact of Sildenafil on RV function as measured by cardiovascular magnetic resonance (CMR) in patients with HF, in the study entitled “The Immediate Effect of Sildenafil on Right Ventricular Function in Patients with Heart Failure Measured by Cardiac Magnetic Resonance: A Randomized Control Trial,” André Maurício S. Fernandes  from the Department of Cardiology at the Hospital Ana Neri in Brazil along with colleagues conducted a randomized double-blind controlled trial in 26 patients with HF. All patients underwent assessment with CMR and the patients were allocated to each of the study arms: 13 patients were assigned to receive 50 mg of Sildenafil and 13 patients were assigned to received a placebo.

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Results revealed that except for the increase in RV fractional area, changes following the administration of sildenafil were not statistically significant in parameters between the two study groups. There was no improvement in left ventricular parameters or in the fractional area change of the pulmonary artery. Based on the results, the researchers concluded that a unique dose of Sildenafil does not improve RV function as measured by the CMR in patients with HF.