Platelet Inhibition in Patients With Systolic Heart Failure
Summary
The investigators aim to determine if patients with systolic heart failure treated with prasugrel achieve greater platelet inhibition compared to those treated with clopidogrel.
Description
Thienopyridine antiplatelet agents are an important component of therapy for management of acute coronary syndrome (ACS). Dual antiplatelet therapy with a thienopyridine, most commonly clopidogrel, and aspirin is widely used in the management of ACS to prevent major adverse cardiovascular events. Despite the benefits of this regimen, many patients continue to develop atherothrombotic events while on this regimen. Various reasons including inter-patient variability, delayed onset of action, and the obtainable antiplatelet activity of clopidogrel have been described as potential causes of the limited efficacy in preventing recurrent events. The Trial to assess improvement in therapeutic outcomes by optimizing platelet inhibition with prasugrel—thrombolysis in myocardial infarction (TRITON-TIMI 38) showed that patients with moderate-to-high-risk ACS scheduled for percutaneous coronary intervention (PCI) treated with prasugrel had decreased cardiovascular events compared to clopidogrel.
Clopidogrel is a prodrug that requires two hepatic conversion steps by the cytochrome (CYP)P450 enzyme system. The need for CYP450 involvement is known to contribute to the variable response of platelet inhibition demonstrated with clopidogrel. Although prasugrel is also a thienopyridine, it only requires hepatic CYP450 enzymes for one conversion step, and is converted to the active metabolite more efficiently. Therefore, prasugrel provides significantly more potent platelet inhibition compared to clopidogrel.
Patients with advanced systolic heart failure commonly have elevated hepatic venous pressures that can cause hepatic congestion and hypoperfusion resulting in impaired hepatic function. The elevated hepatic venous pressure predominantly affects the hepatic centrilobular cells which contain the highest concentration of cytochrome P-450 (CYP450) enzyme system. Hence patients with advanced heart failure may convert less clopidogrel to the active metabolite and subsequently produce less platelet inhibition compared to prasugrel.
Since prasugrel only requires the CYP450 system for one conversion step, the impact of hepatic congestion should be limited for heart failure patients treated with prasugrel. The phase 3, multi-center TRITON-TIMI 38 trial comparing clopidogrel and prasugrel showed that in an unselected patient population presenting with ACS, prasugrel achieved greater cardiovascular event reduction that was attributed to more robust platelet inhibition. Hence, we designed this trial to prospectively test the hypothesis that systolic heart failure patients with increased circulating catecholamines and possible abnormal functioning of CYP450 system treated with prasugrel will achieve greater platelet reactivity inhibition compared to those treated with clopidogrel.
Study Design
Allocation: Randomized, Endpoint Classification: Pharmacodynamics Study, Intervention Model: Crossover Assignment, Masking: Open Label, Primary Purpose: Treatment
Conditions
Systolic Heart Failure
Intervention
Prasugrel 10 mg daily x 2 weeks, Clopidogrel 75 mg daily x 2 weeks
Location
University of Nebaska Medical Center
Omaha
Nebraska
United States
68198
Status
Recruiting
Source
University of Nebraska
Results (where available)
Links
- Source: http://clinicaltrials.gov/show/NCT01765400
- ClinicalTrials.gov processed this data on February 18, 2014
Published on BioPortfolio: 2014-08-27T04:00:37-0400
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Medical and Biotech [MESH] Definitions
Fetal Mortality
Number of fetal deaths with stated or presumed gestation of 20 weeks or more in a given population. Late fetal mortality is death after of 28 weeks or more.
Pregnancy, Prolonged
A term used to describe pregnancies that exceed the upper limit of a normal gestational period. In humans, a prolonged pregnancy is defined as one that extends beyond 42 weeks (294 days) after the first day of the last menstrual period (MENSTRUATION), or birth with gestational age of 41 weeks or more.
Systolic Murmurs
Heart murmurs which are systolic in timing. They occur between the first and the second HEART SOUNDS, between the closure of MITRAL VALVE and TRICUSPID VALVE and the closure of semilunar aortic and pulmonary valves. Systolic murmurs include ejection murmurs and regurgitant murmurs.
Hypertension, Pregnancy-induced
A condition in pregnant women with elevated systolic (>140 mm Hg) and diastolic (>90 mm Hg) blood pressure on at least two occasions 6 h apart. HYPERTENSION complicates 8-10% of all pregnancies, generally after 20 weeks of gestation. Gestational hypertension can be divided into several broad categories according to the complexity and associated symptoms, such as EDEMA; PROTEINURIA; SEIZURES; abnormalities in BLOOD COAGULATION and liver functions.
Cardiomegaly
Enlargement of the HEART, usually indicated by a cardiothoracic ratio above 0.50. Heart enlargement may involve the right, the left, or both HEART VENTRICLES or HEART ATRIA. Cardiomegaly is a nonspecific symptom seen in patients with chronic systolic heart failure (HEART FAILURE) or several forms of CARDIOMYOPATHIES.
