Sildenafil improves exercise hemodynamics and oxygen uptake in patients with systolic heart failure.
BACKGROUND
Heart failure (HF) is frequently associated with dysregulation of nitric oxide-mediated pulmonary vascular tone. Sildenafil, a type 5 phosphodiesterase inhibitor, lowers pulmonary vascular resistance in pulmonary hypertension by augmenting intracellular levels of the nitric oxide second messenger, cyclic GMP. We tested the hypothesis that a single oral dose of sildenafil (50 mg) would improve exercise capacity and exercise hemodynamics in patients with chronic systolic HF through pulmonary vasodilation.


RESULTS
Thirteen patients with New York Heart Association class III HF underwent assessment of right heart hemodynamics, gas exchange, and first-pass radionuclide ventriculography at rest and with cycle ergometry before and 60 minutes after administration of 50 mg of oral sildenafil. Sildenafil reduced resting pulmonary arterial pressure, systemic vascular resistance, and pulmonary vascular resistance, and increased resting and exercise cardiac index (P<0.05 for all) without altering mean arterial pressure, heart rate, or pulmonary capillary wedge pressure. Sildenafil reduced exercise pulmonary arterial pressure, pulmonary vascular resistance, and pulmonary vascular resistance/systemic vascular resistance ratio, which indicates a selective pulmonary vasodilator effect with exercise. Peak VO2 increased (15+/-9%) and ventilatory response to CO2 output (VE/VCO2 slope) decreased (16+/-5%) after sildenafil treatment. Improvements in right heart hemodynamics and exercise capacity were confined to patients with secondary pulmonary hypertension (rest pulmonary arterial pressure >25 mm Hg).


CONCLUSIONS
The present study shows that in patients with systolic HF, type 5 phosphodiesterase inhibition with sildenafil improves peak VO2, reduces VE/VCO2 slope, and acts as a selective pulmonary vasodilator during rest and exercise in patients with HF and pulmonary hypertension.
Lewis
Gregory D
GD
Cardiology Division, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
Lachmann
Justine
J
Camuso
Janice
J
Lepore
John J
JJ
Shin
Jordan
J
Martinovic
Maryann E
ME
Systrom
David M
DM
Bloch
Kenneth D
KD
Semigran
Marc J
MJ
D000328:Adult; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D002302:Cardiac Output / Q000187:drug effects / Q000502:physiology; D002303:Cardiac Output, Low / Q000188:drug therapy / Q000503:physiopathology; D015444:Exercise / Q000502:physiology; D005080:Exercise Test / Q000187:drug effects* / Q000379:methods; D005260:Female; D006339:Heart Rate / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010879:Piperazines / Q000494:pharmacology* / Q000627:therapeutic use; D011659:Pulmonary Gas Exchange / Q000187:drug effects* / Q000502:physiology; D011687:Purines; D000068677:Sildenafil Citrate; D013450:Sulfones; D018487:Ventricular Dysfunction, Left / Q000188:drug therapy* / Q000503:physiopathology
D010879:Piperazines; D011687:Purines; D013450:Sulfones; D000068677:Sildenafil Citrate