Evaluating the Effectiveness of Sildenafil at Improving Health Outcomes and Exercise Ability in People With Diastolic Heart Failure (The RELAX Study) (RELAX)
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ClinicalTrials.gov Identifier: NCT00763867 |
Recruitment Status
:
Completed
First Posted
: October 1, 2008
Results First Posted
: July 3, 2013
Last Update Posted
: July 23, 2014
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Sponsor:
Duke University
Collaborators:
National Heart, Lung, and Blood Institute (NHLBI)
Pfizer
Information provided by (Responsible Party):
Duke University
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Study Type: | Interventional |
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Study Design: | Allocation: Randomized; Intervention Model: Parallel Assignment; Masking: Triple (Participant, Care Provider, Investigator); Primary Purpose: Treatment |
Condition: |
Heart Failure |
Interventions: |
Drug: Placebo Drug: Sildenafil |

Recruitment Details
Key information relevant to the recruitment process for the overall study, such as dates of the recruitment period and locations |
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Pre-Assignment Details
Significant events and approaches for the overall study following participant enrollment, but prior to group assignment |
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Reporting Groups
Description | |
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Placebo | placebo 20 mg three tid for 12 weeks followed by 60 mg tid for 12 weeks |
Sildenafil | sildenafil 20 mg three tid for 12 weeks followed by 60 mg tid for 12 weeks |
Participant Flow: Overall Study
Placebo | Sildenafil | |
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STARTED | 103 | 113 |
COMPLETED | 98 | 101 |
NOT COMPLETED | 5 | 12 |

1. Primary: | Exercise Capacity, as Determined by Peak Oxygen Uptake [ Time Frame: Change from Baseline to Week 24 ] |
2. Secondary: | Exercise Capacity, as Determined by Peak Oxygen Uptake [ Time Frame: Change from Baseline to Week 12 ] |
3. Secondary: | Exercise Capacity as Determined by Walk Distance [ Time Frame: Change from Baseline to Week 12 ] |
4. Secondary: | Composite Score Reflective of Clinical Status [ Time Frame: Measured at Week 24 ] |
5. Secondary: | Exercise Capacity as Determined by Walk Distance [ Time Frame: Change from Baseline to Week 24 ] |
6. Secondary: | Cardiopulmonary Exercise Test (CPET) Duration [ Time Frame: Change from Baseline to Week 12 ] |
7. Secondary: | Cardiopulmonary Exercise Test (CPET) Duration [ Time Frame: Change from Baseline to Week 24 ] |
8. Secondary: | Ventilatory Anaerobic Threshold [ Time Frame: Change from Baseline to Week 12 ] |
9. Secondary: | Ventilatory Anaerobic Threshold [ Time Frame: Change from Baseline to Week 24 ] |
10. Secondary: | Minnesota Living With Heart Failure Questionnaire (MLWHFQ) [ Time Frame: Change from Baseline to Week 12 ] |
11. Secondary: | Minnesota Living With Heart Failure Questionnaire [ Time Frame: Change from Baseline to Week 24 ] |
12. Other Pre-specified: | MRI Left Ventricular Mass [ Time Frame: Change from Baseline to Week 24 ] |
13. Other Pre-specified: | MRI Left Ventricular Mass Index [ Time Frame: Change from Baseline to Week 24 ] |
14. Other Pre-specified: | MRI Left Ventricular End Diastolic Volume [ Time Frame: Change from Baseline to Week 24 ] |
15. Other Pre-specified: | MRI Left Ventricular End Diastolic Volume Index [ Time Frame: Change from Baseline to Week 24 ] |
16. Other Pre-specified: | MRI Left Ventricular End Systolic Volume Index [ Time Frame: Change from Baseline to Week 24 ] |
17. Other Pre-specified: | MRI Left Ventricular Ejection Fraction (LVEF) [ Time Frame: Change from Baseline to Week 24 ] |
18. Other Pre-specified: | Echocardiogram Left Ventricular Mass [ Time Frame: Change from Baseline to Week 24 ] |
19. Other Pre-specified: | Medial Diastolic Elastance [ Time Frame: Change from Baseline to Week 24 ] |
20. Other Pre-specified: | Lateral Diastolic Elastance [ Time Frame: Change from Baseline to Week 24 ] |
21. Other Pre-specified: | Medial Left Ventricular Relaxation [ Time Frame: Change from Baseline to Week 24 ] |
22. Other Pre-specified: | Lateral Left Ventricular Relaxation [ Time Frame: Change from Baseline to Week 24 ] |
23. Other Pre-specified: | Medial Filling Pressure [ Time Frame: Change from Baseline to Week 24 ] |
24. Other Pre-specified: | Lateral Filling Pressure [ Time Frame: Change from Baseline to Week 24 ] |
25. Other Pre-specified: | ECHO Effective Arterial Elastance [ Time Frame: Change from Baseline to Week 24 ] |
26. Other Pre-specified: | ECHO Systemic Vascular Resistance [ Time Frame: Change from Baseline to Week 24 ] |
27. Other Pre-specified: | MRI Effective Arterial Elastance [ Time Frame: Change from Baseline to Week 24 ] |
28. Other Pre-specified: | MRI Systemic Vascular Resistance [ Time Frame: Change from Baseline to Week 24 ] |
29. Other Pre-specified: | MRI Aortic Thickness [ Time Frame: Change from Baseline to Week 24 ] |
30. Other Pre-specified: | MRI Aortic Distensibility [ Time Frame: Change from Baseline to Week 24 ] |
31. Other Pre-specified: | ECHO Pulmonary Artery Systolic Pressure [ Time Frame: Change from Baseline to Week 24 ] |
32. Other Pre-specified: | Best Available Creatinine [ Time Frame: Change from Baseline to Week 24 ] |
33. Other Pre-specified: | Best Available Glomerular Filtration Rate (GFR) [ Time Frame: Change from Baseline to Week 24 ] |
34. Other Pre-specified: | Cystatin C [ Time Frame: Change from Baseline to Week 24 ] |
35. Other Pre-specified: | Uric Acid [ Time Frame: Change from Baseline to Week 24 ] |
36. Other Pre-specified: | N-terminal Pro B-type Natriuretic Peptide (NT Pro-BNP) [ Time Frame: Change from Baseline to Week 24 ] |
37. Other Pre-specified: | Aldosterone [ Time Frame: Change from Baseline to Week 24 ] |
38. Other Pre-specified: | High Sensitivity Troponin I [ Time Frame: Change from Baseline to Week 24 ] |
39. Other Pre-specified: | Procollagen III N-terminal Peptide [ Time Frame: Change from Baseline to Week 24 ] |
40. Other Pre-specified: | Endothelin-1 [ Time Frame: Change from Baseline to Week 24 ] |
41. Other Pre-specified: | High Sensitivity C-Reactive Protein [ Time Frame: Change from Baseline to Week 24 ] |
42. Other Pre-specified: | Collagen Type I (CITP) [ Time Frame: Change from Baseline to Week 24 ] |
43. Other Pre-specified: | Cyclic Guanosine Monophosphate (cGMP) [ Time Frame: Change from Baseline to Week 24 ] |
44. Other Pre-specified: | Galectin 3 [ Time Frame: Change from Baseline to Week 24 ] |
45. Other Pre-specified: | Furosemide-Equivalent Dose [ Time Frame: Change from Baseline to Week 24 ] |

Limitations of the study, such as early termination leading to small numbers of participants analyzed and technical problems with measurement leading to unreliable or uninterpretable data |
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