Key result
Sildenafil demonstrated a pulmonary vasodilatory effect and improved symptoms in small, short-term studies of patients with pulmonary hypertension, but evidence is insufficient to establish long-term efficacy.
Why the study?
Does sildenafil improve NYHA functional class and symptoms in patients with primary or secondary pulmonary hypertension?
Systematic Review (n=77)
Does sildenafil improve NYHA functional class and symptoms in patients with primary or secondary pulmonary hypertension?
Sildenafil demonstrates acute pulmonary vasodilatory effects and short-term symptom improvement in pulmonary hypertension, but larger, long-term trials are needed to confirm clinical benefits.
Short-term symptom relief supports cautious trial in pulmonary hypertension; leaves open long-term efficacy and safety.
Pulmonary Hypertension (PH) can be either of unknown aetiology (primary pulmonary hypertension (PPH)) or due to a known underlying cause (secondary pulmonary hypertension (SPH). Pulmonary arteriolar vasoconstriction is considered to be an important characteristic of PH. Therapies which aim to vasodilate are used to treat pulmonary hypertension.To determine the clinical efficacy of sildenafil, a vasodilator which works through inhibition of the enzyme phosphodiesterase type V (PDE5I), administered via any route to people with pulmonary hypertension in primary or secondary forms.Electronic databases were searched with pre-defined search terms. Searches were current as of November 2003.Randomised controlled trials were considered for inclusion in the review. We included studies which assessed the effects of sildenafil in participants with PPH and SPH.Two reviewers independently assessed and extracted data from clinical trials. Data were entered in RevMan Analyses 1.0.2. Continuous data were pooled with an estimate on either WMD (weighted mean difference) or SMD (standardised mean difference) scales. Dichotomous data were pooled and a RR (relative risk) was calculated.Four studies recruiting 77 participants met the inclusion criteria of the review. Two studies assessed the acute effects of sildenafil. Two small crossover study assessed the effects of long term administration. The 'acute effect' studies indicated that sildenafil has a pulmonary vasodilatory effect. The two crossover studies showed improvement in symptoms. One study showed improvement in fatigue domains from a validated health status questionnaire. Both crossover studies reported that the drug was well tolerated.The validity of the observed effects is undermined by small participant numbers and inadequate exploration of the different disease etiologies. The effects on long term outcome such as NYHA functional class, symptoms, mortality and exercise capacity require further validation. More studies of adequate size are required before the long term effects of sildenafil on clinically important outcomes can be established.
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Kanthapillai et al. (2004) conducted a systematic review in Pulmonary hypertension (n=77). Sildenafil vs. Placebo or active control (prostacyclin, inhaled NO) was evaluated on Improvement in NYHA functional class status. Sildenafil demonstrated a pulmonary vasodilatory effect and improved symptoms in small, short-term studies of patients with pulmonary hypertension, but evidence is insufficient to establish long-term efficacy.
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