Background—: The prevalence of heart failure with preserved ejection fraction is increasing. The prognosis worsens with pulmonary hypertension and right ventricular (RV) failure development. We targeted pulmonary hypertension and RV burden with the phosphodiesterase-5 inhibitor sildenafil. Methods and Results—: Forty-four patients with heart failure with preserved ejection fraction (heart failure signs and symptoms, diastolic dysfunction, ejection fraction ≥50%, and pulmonary artery systolic pressure >40 mm Hg) were randomly assigned to placebo or sildenafil (50 mg thrice per day). At 6 months, there was no improvement with placebo, but sildenafil mediated significant improvements in mean pulmonary artery pressure (−42.0±13.0%) and RV function, as suggested by leftward shift of the RV Frank-Starling relationship, increased tricuspid annular systolic excursion (+69.0±19.0%) and ejection rate (+17.0±8.3%), and reduced right atrial pressure (−54.0±7.2%). These effects may have resulted from changes within the lung (reduced lung water content and improved alveolar-capillary gas conductance, +15.8±4.5%), the pulmonary vasculature (arteriolar resistance, −71.0±8.2%), and left-sided cardiac function (wedge pulmonary pressure, −15.7±3.1%; cardiac index, +6.0±0.9%; deceleration time, −13.0±1.9%; isovolumic relaxation time, −14.0±1.7%; septal mitral annulus velocity, −76.4±9.2%). Results were similar at 12 months. Conclusions—: The multifaceted response to phosphodiesterase-5 inhibition in heart failure with preserved ejection fraction includes improvement in pulmonary pressure and vasomotility, RV function and dimension, left ventricular relaxation and distensibility (structural changes and/or ventricular interdependence), and lung interstitial water metabolism (wedge pulmonary pressure decrease improving hydrostatic balance and right atrial pressure reduction facilitating lung lymphatic drainage). These results enhance our understanding of heart failure with preserved ejection fraction and offer new directions for therapy. Clinical Trial Registration—: URL: http://www.clinicaltrials.gov . Unique identifier: NCT01156636.

Background—: In heart failure (HF), a defective nitric oxide signaling is involved in left ventricular (LV) diastolic abnormalities and remodeling. PDE5 inhibition, by blocking degradation of nitric oxide second-messenger cyclic guanosine monophosphate, might be beneficial. In a cohort of systolic HF patients, we tested the effects of PDE5 inhibition (sildenafil) on LV ejection fraction, diastolic function, cardiac geometry, and clinical status. Methods and Results—: Forty-five HF patients (New York Heart Association class II-III) were randomly assigned to placebo or sildenafil (50 mg three times per day) for 1 year, with assessment (6 months and 1 year) of LV ejection fraction, diastolic function, geometry, cardiopulmonary exercise performance, and quality of life. In the sildenafil group only, at 6 months and 1 year, LV ejection fraction, early diastolic tissue Doppler velocities (E′) at the mitral lateral (from 4.62 to 5.20 and 5.19 m/s) and septal (from 4.71 to 5.23 and 5.24 m/s) annuli significantly increased, whereas the ratio of early transmitral (E) to E′ lateral decreased (from 13.1 to 9.8 to 9.4) ( P <0.01). Changes were accompanied by a reverse remodeling of left atrial volume index (from 32.0 to 29.0 and 29.1 mL/m ² ; P <0.01) and LV mass index (from 148.0 to 130.0 and 128.0 g/m ² ; P <0.01). Furthermore, sildenafil improved exercise performance (peak V o ₂ ), ventilation efficiency (ventilation to CO ₂ production slope), and quality of life ( P <0.01). Minor adverse effects were noted: flushing in 4 and headache in 2 treated patients. Conclusions—: Findings confirm that in HF, sildenafil improves functional capacity and clinical status and provide the first human evidence that LV diastolic function and cardiac geometry are additional targets of benefits related to chronic PDE5 inhibition. Clinical Trial Registration—: URL: http://www.clinicaltrials.gov . Unique identifier: NCT00975494.

The six-minute walk test (6MWT) and cardiopulmonary exercise testing (CPET) are the 2 testing modalities most broadly used for assessing functional limitation in patients with heart failure (HF). A comprehensive comparison on clinical and prognostic validity of the 2 techniques has not been performed and is the aim of the present investigation. Two hundred fifty-three patients diagnosed with systolic (n=211) or diastolic (n=42) HF (age: 61.9+/-10.1 years; New York Heart Association Class: 2.2+/-0.78) underwent a 6MWT and a symptom-limited CPET evaluation and were prospectively followed up. During the 4-year tracking period, there were 43 cardiac-related deaths with an annual cardiac mortality rate of 8.7%. The 6MWT distance correlated with CPET-derived variables (ie, peak Vo(2), Vo(2) at anaerobic threshold, and Ve/Vco(2) slope) and was significantly reduced in proportion with lower peak Vo(2) and higher Ve/Vco(2) slope classes and presence of an exercise oscillatory breathing (EOB) pattern (P<0.01). However, no significant differences were observed in distance covered between survivors and nonsurvivors (353.2+/-95.8 m versus 338.5+/-76.4 m; P=NS). At univariate and multivariate Cox proportional analyses, the association of the 6MWT distance with survival was not significant either as a continuous or dicotomized variable (< or =300 m). Conversely, CPET-derived variables emerged as prognostic with the strongest association found for EOB (systolic HF) and Ve/Vco(2) slope (entire population with HF and patients with a 6MWT< or =300 m). The 6MWT is confirmed to be a simple and reliable first-line test for quantification of exercise intolerance in patients with HF. However, there is no supportive evidence for its use as a prognostic marker in alternative to or in conjunction with CPET-derived variables.