Abstract 2949: Improvement in Ventilatory Efficiency and Dyspnea on Exertion Are Related to Reduced Pulmonary Pressure in Heart Failure Patients Undergoing Chronic Phosphodiesterase-5 Inhibition
Chronic phosphodiesterase-5 inhibition with Sildenafil has been shown to improve peak oxygen consumption (VO2), ventilatory efficiency (VE/VCO2 slope) and pulmonary artery pressure (PAP) in patients with heart failure (HF). The impact of Sildenafil on dyspnea on exertion (DOE) or the relationship between changes in the exercise response and pulmonary hemodynamics following use of this pharmacologic agent are unknown. We addressed the hypothesis that DOE would be reduced and improvements in the exercise response would be correlated with pulmonary hemodynamics following three months of treatment with Sildenafil. Forty male patients with HF (age: 65.3 ±7.3 years; ejection fraction 37.1 ±7.4%) underwent cardiopulmonary exercise testing and right heart catheterization prior to and following three months of treatment with Sildenafil at the dose of 50 mg three times per day, while maintaining standard pharmacologic management. The 0–10 Borg scale was used to assess DOE at maximal exercise. Three-months of Sildenafil treatment resulted in a significant (p<0.001 for all) increase in peak VO2 (mean change: 1.3 ±0.78 mlO2·kg−1·min−1; range: 0–3 mlO2·kg−1·min−1) and a significant reduction in the VE/VCO2 slope (mean change: 2.2 ±1.6; range: −1 to 6), DOE at maximal exercise (mean change: 0.98 ±0.83; range: −1 to 2) and mean PAP (mean change: 5.2 ±4.5 mmHg; range: −1 to 18 mmHg). The correlations between the change in mean PAP and both the change in the VE/VCO2 slope (Pearson’s r = 0.57, p<0.001) and DOE at maximal exercise (Spearman’s r = 0.49, p=0.001) were significant. The correlation between change in mean PAP and change in peak VO2 (Pearson’s r = −0.02, p=0.90) was, however, not significant. The results of the present study are consistent with previous findings demonstrating a significant improvement in aerobic capacity, ventilatory efficiency and pulmonary hemodynamics after chronic administration of Sildenafil in HF. The findings presented here expand upon this area by demonstrating that: 1) DOE at maximal exercise, an important subjective measure, is significantly reduced and 2) The degree of improvement in mean PAP is reflected by the degree of improvement in the VE/VCO2 slope and DOE, but not peak VO2.