SToPClot: Sildenafil To Prevent Clot
Study Details
Study Description
Brief Summary
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.
| Condition or Disease | Intervention/Treatment | Phase |
|---|---|---|
|
Early Phase 1 |
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 in outpatients on chronic CF pump support can be reduced by sildenafil.
Study Design
Arms and Interventions
| Arm | Intervention/Treatment |
|---|---|
| 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:
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| 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:
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Outcome Measures
Primary Outcome Measures
- Change in platelet activation and aggregation (aggregometry) [Baseline, day 8 and day 15]
During the study period platelet activation and aggregation will be measured from drawn blood samples. Platelet rich plasma will be isolated from these samples and platelet aggregometry will be used to measure platelet activation and aggregation.
Secondary Outcome Measures
- Changes in Endothelial Function as measured by the vascular reactivity index (VRI) [Baseline, day 8 and day 15]
During the study period endothelial function will be measured by the VRI as calculated by the Endothelix device, after a 5 minute blood pressure cuff occlusion of the brachial artery.
- Changes in Endothelial Function as measured by Endothelin 1 [Baseline, day 8 and day 15]
During the study period changes in endothelial function, will be measured by blood endothelin-1 (pg/mL) levels trough ELISA
- Change in pro-thrombotic inflammatory markers as measured by hs CRP [Baseline, day 8 and day 15]
During the study period pro-thrombotic inflammatory markers, including hs CRP (mg/L) in serum will be measured by ELISA.
- Change in pro-thrombotic inflammatory markers as measured by fibrinogen [Baseline, day 8 and day 15]
During the study period pro-thrombotic inflammatory markers including fibrinogen (mg/dL) will be measured by ELISA.
Eligibility Criteria
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
Contacts and Locations
Locations
| Site | City | State | Country | Postal Code | |
|---|---|---|---|---|---|
| 1 | Montefiore Medical Center | Bronx | New York | United States | 10467 |
Sponsors and Collaborators
- Montefiore Medical Center
Investigators
- Principal Investigator: Omar Saeed, MD, Montefiore Medical Center
Study Documents (Full-Text)
None provided.More Information
Publications
None provided.- 2016-7404