Effects of Viagra on Heart Function in Patients With Heart Failure
Condition: Heart Failure; Left Ventricular Dysfunction
MeSH terms: Heart Failure; Ventricular Dysfunction; Ventricular Dysfunction, Left
Study type: Interventional
Phase: Phase 4

Summary: 
      Sildenafil (Viagra) is known to reduce pulmonary hypertension. Heart failure patients also
      have pulmonary hypertension and several recent reports have shown that sildenafil leads to an
      improvement in their exercise capacity. In these studies sildenafil caused a reduction in the
      pulmonary and systemic vascular resistances, improved pulmonary gas diffusion and perhaps
      increased cardiac output. It is uncertain if left ventricular filling pressures are reduced
      and whether there is improvement in left ventricular relaxation. The investigators
      hypothesize that in heart failure patients the improvement in exercise capacity associated
      with sildenafil is related to a significant reduction in left ventricular filling pressures.
      The investigators propose to study 20 patients with stable but moderately symptomatic heart
      failure. The study design is a randomized cross-over trial of the administration of a single
      dose of sildenafil 50 mg or a matching placebo. Exercise capacity will be determined before
      and after the oral administration of sildenafil 50 mg or placebo. Left ventricular filling
      pressures will be assessed by Doppler echocardiography and the serum level of B-type
      natriuretic peptide (BNP is known to increase with higher left ventricular filling
      pressures). After an initial echocardiogram and performing a 6 minute walk test, the patient
      will then be given either sildenafil or a matching placebo in a randomized double-blind
      fashion. One hr later a blood sample for serum BNP, the echocardiogram and the 6 minute walk
      test will be repeated.
    

Detailed description: 
      Sildenafil (Viagra) has been extensively studied in patients with idiopathic pulmonary
      hypertension. It reduces pulmonary vascular resistance, improves exercise capacity and is now
      an approved therapy for this condition. Heart failure (HF) patients also have pulmonary
      hypertension and several recent reports have shown that sildenafil leads to an improvement in
      their exercise capacity. In HF sildenafil causes a reduction in the pulmonary and systemic
      vascular resistances, improves pulmonary gas diffusion and perhaps increases cardiac output.
      It is uncertain if left ventricular filling pressures are reduced and whether there is
      improvement in left ventricular relaxation. We hypothesize that in HF patients the
      improvement in exercise capacity associated with sildenafil is related to a significant
      reduction in left ventricular filling pressures. We propose to study 10 patients with stable,
      symptomatic HF Class III. The study design is a randomized cross-over assignment of the
      administration of a single oral dose of sildenafil 50 mg or a matching placebo. Patients will
      be excluded if walking is impaired due to non-cardiac conditions or if they are taking
      nitrates. Exercise capacity will be determined before and 60 minutes after the oral
      administration of sildenafil 50 mg or placebo. The difference in the standardized 6 minute
      walk test (distance patient is able to walk over a 6 minute interval) will be used to assess
      exercise capacity. Left ventricular filling pressures will be assessed by Doppler
      echocardiography and the serum level of B-type natriuretic peptide (BNP). Evaluation of left
      ventricular relaxation will be determined by Doppler echocardiography techniques. Each
      patient will have a blood sample for BNP, an initial echocardiogram and perform a 6 minute
      walk test. They will then be given a single dose of either sildenafil or a matching placebo
      in a randomized double-blind fashion. The randomization was performed so that half of the
      group would receive the placebo on the initial test and sildenafil on the subsequent test and
      the other half would have the reverse sequence. One hr after the medication/placebo
      administration a blood sample for serum BNP, the echocardiogram and the 6 minute walk test
      will be repeated. After completion of the above protocol, the patient will return in 48 hrs
      and the protocol will be repeated with the predetermined assignment of either placebo or
      sildenafil.
    

Intervention name(s): sildenafil; Placebo
Intervention type(s): Drug; Other
Intervention description(s): Changes in left ventricular filling pressure 1 hour after the administration of a single oral dose of sildenafil 50 mg.; Changes in left ventricular filling pressure 1 hour after oral administration of placebo
Other intervention name(s): Viagra
Intervention MeSH terms: Sildenafil Citrate
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Treatment
Keywords: heart failure, left sided; ventricular dysfunction; diastolic dysfunction; sildenafil