Sildenafil therapy in secondary pulmonary hypertension: Is there benefit in prolonged use?

BACKGROUND: Sildenafil is of benefit to selected patients with pulmonary hypertension due to parenchymal lung or cardiac disease. We present data from patients with secondary pulmonary hypertension, comparing their right heart catheter results and six minute walking distance to time on treatment.

METHODS: 25 patients with symptomatic secondary pulmonary hypertension received sildenafil 50 mg tds in a 5-year period. Underlying causes were chronic inoperable thromboembolic disease (11), COPD (6), interstitial lung disease (5) and valvular heart disease (3). Their cardio-pulmonary haemodynamics were measured with right heart catheterization prior to treatment, post-treatment at 2, 6 and 12 months and subsequently depending upon clinical need. Six-minute walk distance was also measured.

RESULTS: Patient age range was 40 to 83 (median 70.5) years. Time of treatment to latest right heart catheter was 2 to 60 (median 17) months and 8 to 61 (median 34) months to clinic follow-up or death. There was a significant reduction in six-minute walk distance from baseline to long term (>12 months) follow-up (p=0.002). Pulmonary vascular resistance was significantly reduced from baseline to 12 months (p=0.049). The mean pulmonary arterial (PA) pressure was significantly reduced at long-term follow-up (p=0.009). 20 patients had an improved PA pressure with treatment. In those with a worsening PA pressure, two had an improvement in cardiac output and six minute walk distance, two had stable cardiac output at 20 and 21 months, and one had measurements taken during a significant illness. Three patients, who had a reduction in PA pressure, subsequently died of progression of underlying illness at 8 months, from myocardial infarction at 34 months, and from aspergillus pneumonia at 59 months.

CONCLUSION: Long-term use of sildenafil in patients with secondary forms of pulmonary hypertension is associated with a sustained improvement in cardio-pulmonary haemodynamics. Lack of improvement may be attributed to other factors apart from treatment failure, such as underlying disease progression or unrelated concurrent illness at time of assessment.