Purpose

The advent of continuous flow (CF) pumps for patients with severe heart failure has led to marked improvements in survival; however, pump operation remains fraught with adverse thrombotic events. This climbing rate of thrombosis and stroke during CF pump support has led to a recent warning by the US Food and Drug Administration. Despite a rising incidence of pump thrombosis and its downstream complications of stroke, the hematologic mechanisms behind these devastating adverse events remain uncertain. Recently, it has been recognized that CF pump induced hemolysis precedes and is associated with thrombosis. In-vitro studies show increased platelet function with exposure to products of hemolysis, which is also known to occur in diseases of intravascular hemolysis such as sickle cell anemia. This proposal will investigate if hemolysis associated increased platelet function can be reduced by a potentiation of nitric oxide signaling by an oral phosphodiesterase-5 inhibitor, sildenafil. Elucidating mechanisms of hemolysis induced thrombosis may inform best strategies for prevention of end organ damage and maintaining optimal CF pump operation.

Conditions

Eligibility

Eligible Ages
Over 18 Years
Eligible Genders
All
Accepts Healthy Volunteers
No

Criteria


Inclusion:

-Adult outpatients (≥18 years old) with ongoing durable CF pump support.

Exclusion:

- Taking sildenafil or nitrates for clinical indications

- Ongoing infection

- Unwilling or unable to give written, informed consent

Study Design

Phase
Early Phase 1
Study Type
Interventional
Allocation
Randomized
Intervention Model
Parallel Assignment
Intervention Model Description
Placebo controlled randomized trial with 1:1 enrollment in each study arm.
Primary Purpose
Treatment
Masking
Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)

Arm Groups

ArmDescriptionAssigned Intervention
Active Comparator
Sildenafil
Baseline blood samples and study measurements will be acquired. Then 20 mg of the study drug will be administered. Then BP will be recorded every 30 minutes for two hours. If BP is stable (drop is < 5 mmHg after 2 hours and patient is asymptomatic), patient will proceed to take 20 mg of the study drug every 8 hours. The patient will return to clinic on day 8 and 20 mg of the study drug will be administered. After 2 hours blood samples and study measurements will be collected and the patient will resume 20 mg of the study for the next two doses. The patient will return for a third clinic visit on the next day and if BP is in the acceptable range, 40 mg of the study drug will be administered. If BP remains stable for 2 hours, then the patient will continue taking 40 mg every 8 hours. The patient will return to clinic on day 15 for a final study visit and will be given the last 40 mg dose of the study drug and after 2 hours blood samples and study measurements will be taken.
  • Drug: Sildenafil
    To conduct a randomized placebo controlled study to test the hypothesis that platelet activation and aggregation during ongoing low level hemolysis in outpatients on chronic CF pump support can be reduced by sildenafil.
    Other names:
    • Viagra
    • Revatio
Placebo Comparator
Placebo Oral Tablet
Negative control to understand the potential changes in platelet activation and aggregation in comparison to sildenafil.
  • Drug: Placebo Oral Tablet
    Negative control to understand the potential changes in platelet activation adn aggregation in comparison to sildenafil.
    Other names:
    • Sildenafil matching placebo

Recruiting Locations

Montefiore Medical Center
Bronx, New York 10467
Contact:
Omar Saeed, MD
718-920-2626
osaeed@montefiore.org

More Details

NCT ID
NCT03199612
Status
Recruiting
Sponsor
Montefiore Medical Center

Study Contact

Thiru Chinnadurai, MD
718-920-2626
tchinnad@montefiore.org

Detailed Description

Despite the remarkable improvements in survival with durable continuous flow (CF) pumps and the clear lifesaving effects of Impella and veno-arterial extracorporeal membrane oxygenation (VA ECMO), serious adverse hematological events such as bleeding and thrombosis create substantial morbidity and mortality and remain major barriers for further expansion of this technology. In particular, thrombosis is a devastating adverse event during CF pump support as it can lead to stroke, device stoppage, and hemodynamic collapse. Although the annual incidence of pump thrombosis has been reported to range from 8 to nearly 30%, the pathobiological mechanisms of thrombus formation during CF pump support with ongoing anticoagulation remain elusive. Our preliminary data associates hemolysis, which is inherent to such devices due to high shear stress, with subsequent formation of thrombosis and stroke, possibly through increasing platelet activation and aggregation. Our prelim data and drawing from a body of literature from diseases of intravascular hemolysis such as sickle cell anemia suggest that free hemoglobin released during hemolysis, which reduces NO levels, may be activating platelets. In retrospective analysis, we have noted a significant reduction in mean platelet volume (potential in-vivo marker of platelet activation), thrombosis and stroke with concurrent sildenafil administration. However, this mechanism and efficacy of NO signaling enhancers such as sildenafil remains to be proven during CF pump support.

Aim: To conduct a randomized placebo controlled study to test the hypothesis that platelet activation and aggregation, endothelial dysfunction and pro-thrombotic inflammation during ongoing low level hemolysis in outpatients on chronic CF pump support can be reduced by sildenafil.

Notice

Study information shown on this site is derived from ClinicalTrials.gov (a public registry operated by the National Institutes of Health). The listing of studies provided is not certain to be all studies for which you might be eligible. Furthermore, study eligibility requirements can be difficult to understand and may change over time, so it is wise to speak with your medical care provider and individual research study teams when making decisions related to participation.