Background: Although platelet activation plays a major role in the pathogenesis of atherothrombotic events, only few data exist regarding the predictors and modulators of platelet activity in healthy subjects.
Methods: To explore the long-term association between brachial artery FMD, platelet function, cardiovascular (CV) events (all-cause mortality, nonfatal myocardial infarction, hospitalization for heart failure or angina pectoris, stroke, coronary artery bypass grafting, and percutaneous coronary intervention) and non-CV events in healthy subjects, we prospectively assessed brachial FMD in 89 consecutive healthy subjects 64 (72%) men, mean age 51±11 years. Platelet aggregation was assessed by conventional aggregometry, and platelet adhesion and aggregation under flow conditions by cone-and-plate(let) technology (Impact-R).
Results: After a mean follow-up of 90±6 months (range: 79-102) there were 29 total events of which 11 were CV end points. All subjects with- but only 68% without CV events were males (p=0.02). There were no significant differences between subjects with (n=11) and without (n=78) CV events in regard to age, CV risk factors, left ventricular ejection fraction and lipoproteins, although fasting glucose and homocystein were higher in those with compared to without CV events (p<0.05). Subjects with CV events had significantly lower FMD compared to those without CV events (10.4±8.0% vs 17.5±9.7%, p=0.02), while NTG was similar in both groups. ADP- and arachidonic acid-induced platelet aggregation were significantly higher in subjects with compared to those without CV events (p<0.01). In addition, platelet adhesion which reflects platelet reactivity, as seen by surface coverage (SC) under flow conditions, was greater in those with than without CV events (14±8% vs 9±6%, p<0.05). Furthermore, more subjects without compared with CV events had platelet SC < the median (62% vs 27%, p=0.02) (Table).
Table: Platelet function test results
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No cardiac events (n=78)
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Cardiac events (n=11)
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P value
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|
Conventional aggregometry:
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|
|
|
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ADP-induced aggregation (%)
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60±28
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79±18
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0.005
|
|
AA-induced aggregation (%)
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51±32
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75±31
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0.017
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|
Platelet deposition under flow conditions:
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|
|
|
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CPA and surface coverage (%)
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9.3±6.2
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13.6±8.2
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0.046
|
|
CAP, surface coverage, and ADP (%)
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2.9±2.2
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4.9±2.9
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0.007
|
Values are presented as mean±SD; ADP, adenosine diphosphate; AA, arachidonic acid; CPA, cone and plate(let) analyzer
Conclusions: Platelet function tests are associated with long-term CV events in subjects without heart disease. Larger prospective, long-term studies are required to determine the clinical value of these results.
