Sildenafil Worsens Outcomes in Pulmonary Hypertension Following Heart Valve Surgery

When sildenafil is used to treat residual pulmonary hypertension in patients following surgery for valvular heart disease, it could do more harm than good. This finding of the Sildenafil for Secondary Pulmonary Hypertension Due to Valvular Disease (SIOVAC) trial was presented at the European Society of Cardiology Congress. Sildenafil is a drug that became extremely popular soon after its introduction in the market due to its benefits in male impotence / erectile dysfunction. Several instances of cardiovascular events were reported following the intake of the medication by patients with preexisting cardiovascular risk factors or with the intake of nitrates (drugs commonly used in the
treatment of angina).

Sildenafil is also used for the pulmonary arterial hypertension. The pulmonary arteries are blood vessels that carry deoxygenated blood from the right side of the heart to the lungs to get oxygenated; the blood is then returned to the left side of the heart through the pulmonary veins.

A high pressure in these arteries means that the heart has to pump against greater resistance, and the work load of the heart is increased. The patient may suffer from shortness of breath, chest pain and swelling of the ankles and feet. If left untreated, eventually, the patient could suffer from heart failure. Sildenafil relaxes the smooth muscles of the pulmonary blood vessels thereby reducing the vascular resistance. Thus, it improves exercise tolerance and delays clinical worsening.

Scientists have now warned against the use of sildenafil in treating residual hypertension in patient with valvular heart disease. The heart valves are responsible for the unidirectional flow of blood. Diseases of the heart valves can either result in narrowing of the openings in the heart valves (stenosis), or backflow of the blood (regurgitation). Severe heart valve disease is treated surgically, through repair or replacement or dilatation of the valve.

Patients who suffer from pulmonary hypertension before heart valve surgery often continue to experience residual hypertension after the surgery as well. The pulmonary hypertension can result in disability and even death.

The Sildenafil for Secondary Pulmonary Hypertension Due to Valvular Disease (SIOVAC) conducted a study in 200 patients who had heart valve surgery at least a year before they were included in the study. The patients received either sildenafil in a dose of 40 mg three times a day (104 patients) or placebo (96 patients) for a duration of 6 months. At the end of the study, the scientists found that:

• The clinical scores of 33 patients taking sildenafil and 14 patients taking placebo were worse as compared to the beginning of the study. The scores considered all-cause death, hospital admission for heart failure, worsening exercise tolerance, and feeling worse than when starting the medication. The scores of 37 patients taking sildenafil and 32 patients taking placebo remained unchanged, while those of 27 patients taking sildenafil and 44 patients taking placebo improved.

• The risk of hospitalization due to heart failure was more in the patients taking sildenafil; the overall risk for hospitalization was double in patients who received sildenafil as compared to those who received placebo

• The mortality rate did not differ significantly between the two groups, with three deaths in the sildenafil group and two in the placebo group.

The exact reason for the worsening of the clinical condition in the patients taking sildenafil has not been established. However, the information will be useful to clinicians who have been using the drug for this purpose.

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Reference:

1. Sildenafil should be avoided in valve disease with residual pulmonary hypertension (SIOVAC) - (https://www.escardio.org/The-ESC/Press-Office/Press-releases/sildenafil-should-be-avoided-in-valve-disease-with-residual-pulmonary-hypertension-siovac)

Source-Medindia