Sildenafil preserves exercise capacity in patients with idiopathic pulmonary fibrosis and right-sided ventricular dysfunction

Abstract

Background: Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease with pulmonary vasculopathy.

Objective: The purpose of this study was to determine whether sildenafil improves 6-min walk distance (6MWD) in subjects with IPF and right ventricular dysfunction.

Methods: The IPFnet, a network of IPF research centers in the United States, conducted a randomized trial examining the effect of sildenafil on 6MWD in patients with advanced IPF, defined by carbon monoxide diffusing capacity < 35% predicted. A substudy examined 119 of 180 randomized subjects where echocardiograms were available for independent review by two cardiologists. Right ventricular (RV) hypertrophy (RVH), right ventricular systolic dysfunction (RVSD), and right ventricular systolic pressure (RVSP) were assessed. Multivariable linear regression models estimated the relationship between RV abnormality, sildenafil treatment, and changes in 6MWD, St. George's Respiratory Questionnaire (SGRQ), the EuroQol instrument, and SF-36 Health Survey (SF-36) from enrollment to 12 weeks.

Results: The prevalence of RVH and RVSD were 12.8% and 18.6%, respectively. RVSP was measurable in 71 of 119 (60%) subjects; mean RVSP was 42.5 mm Hg. In the subgroup of subjects with RVSD, subjects treated with sildenafil experienced less decrement in 6MWD (99.3 m; P = .01) and greater improvement in SGRQ (13.4 points; P = .005) and EuroQol visual analog scores (17.9 points; P = .04) than subjects receiving placebo. In the subgroup with RVH, sildenafil was not associated with change in 6MWD (P = .13), but was associated with greater relative improvement in SGRQ (14.8 points; P = .02) vs subjects receiving placebo. Sildenafil treatment in those with RVSD and RVH was not associated with change in SF-36.

Conclusions: Sildenafil treatment in IPF with RVSD results in better preservation of exercise capacity as compared with placebo. Sildenafil also improves quality of life in subjects with RVH and RVSD.

Figure 1.

Consolidated Standards of Reporting Trials Diagram.

Figure 2.

Change in 6MWD at 12 weeks by treatment and presence of RVSD. + = mean. The box represents the 25th-75th percentiles. The line within the box is the 50th percentile. The upper and lower hinges represent the minimum and maximum values. Higher values indicated improvement. 6MWD = 6-min walk distance; RVSD = right-sided ventricular systolic dysfunction.

Figure 3.

Change in 6MWD at 12 weeks by treatment and presence or RVH. + = mean. The box represents the 25th-75th percentiles. The line within the box is the 50th percentile. The upper and lower hinges represent the minimum and maximum values. Higher values indicated improvement. RVH = right-sided ventricular hypertrophy. See Figure 2 legend for expansion of other abbreviations.

Figure 4.

Change in SGRQ total score at 12 weeks by treatment and presence or RVSD. + = mean. The box represents the 25th-75th percentiles. The line within the box is the 50th percentile. The upper and lower hinges represent the minimum and maximum values. Lower values indicated improvement. SGRQ = St George’s Respiratory Questionnaire. See Figure 1 and 2 legends for expansion of other abbreviations.

Figure 5.

Change in SGRQ total score at 12 weeks by treatment and presence or RVH. + = mean. The box represents the 25th-75th percentiles. The line within the box is the 50th percentile. The upper and lower hinges represent the minimum and maximum values. Lower values indicated improvement. See Figure 3 and 4 legends for expansion of abbreviations.