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Protein S and Myocardial Infarction

This study has been completed.
Information provided by:
National Heart, Lung, and Blood Institute (NHLBI) Identifier:
First received: May 25, 2000
Last updated: May 12, 2016
Last verified: March 2005
To test the hypothesis that low levels of free protein S, a natural anticoagulant protein in plasma, were associated with an increased incidence of myocardial infarction in middle aged men and women.

Cardiovascular Diseases
Heart Diseases
Myocardial Infarction

Study Type: Observational

Resource links provided by NLM:

Further study details as provided by National Heart, Lung, and Blood Institute (NHLBI):

Study Start Date: May 1992
Study Completion Date: March 1997
Detailed Description:


Free protein S (that portion of plasma protein S which is not in complex with C4b binding protein) is a cofactor for the anticoagulant effect of activated protein C. Patients presenting with acute myocardial infarction have significantly reduced levels of free protein S. If the major hypothesis proved correct, patients at high risk of myocardial infarction could be identified and could be targeted for future studies to examine specific intervention therapy.


The blinded and prospective study began in 1992, although the grant was first awarded in 1983. The goal was to determine if low levels of free protein S were associated with an increased incidence of myocardial infarction. Plasma samples were obtained yearly from 2,224 men aged 50-59 years who were participants in the Second Northwick Park Heart Study sponsored by the British Medical Research Council Epidemiology and Medical Care Unit. Clinical endpoints for the study were documented fatal and non-fatal myocardial infarction. To prevent potential bias, this laboratory was blinded to the clinical endpoints until all samples had been collected and all causes of death in the study population had been adjudicated. ln addition to free protein S, total protein S and C4b binding protein were measured. The study design permitted the assessment of the temporal relationship between the development of low free protein S levels and the occurrence of myocardial infarction and the presence or absence of a biologic gradient (dose-response) between levels of free protein S and the frequency of infarction. These two analyses were important in assessing whether the observed association was causal or whether low protein S occured as a consequence of myocardial infarction. Three levels of free protein S had been defined prior to initiating the study to determine if the frequency of myocardial infarction did follow a biologic gradient. The measurement of other potential markers of risk by other laboratories, such as prothrombin fragment Fl+2 and factor X activation peptide, permitted a comprehensive evaluation of hemostatic risk factors in myocardial infarction. A second study was conducted in women to examine protein S as a risk factor for myocardial infarction.

The study completion date listed in this record was obtained from the "End Date" entered in the Protocol Registration and Results System (PRS) record.


Ages Eligible for Study:   up to 100 Years   (Child, Adult, Senior)
Sexes Eligible for Study:   Male
Accepts Healthy Volunteers:   No
No eligibility criteria
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Please refer to this study by its identifier: NCT00005329

Sponsors and Collaborators
National Heart, Lung, and Blood Institute (NHLBI)
OverallOfficial: Philip Comp University of Oklahoma Hlth Sciences Ctr