Platelet hyperreactivity: predictive and intrinsic properties

Abstract

Platelet thrombi are central to the development of most vascular ischemic events. There is marked interindividual variation in platelet responsiveness, with some subjects displaying platelet hyperreactivity. An increasing number of reports indicate that there are laboratory measures of platelet function that predict clinical thrombotic events. Some, but not all, measures of platelet function are reproducible. Platelet hyperreactivity can be assessed with multiple stimuli in multiple assays and is more likely to be present in women and in subjects who have elevated fibrinogen levels.

Figure 1. Schema indicating the multifactorial nature of thrombosis

The central role of platelets is emphasized.

Figure 2. Variation in platelet reactivity

The lumiaggregation response in plateletrich plasma in response to increasing concentrations of type I acid soluble collagen is shown. The box indicates the 25^th-75^th percentiles, the line in the box indicates the median, the lines outside the box indicate the 10^th and 90^th percentiles, and the dots are the outliers below the 10^th percentile and above the 90^th percentile. An arbitrary group of hyperreactive outliers is circled.

Figure 3. Association between platelet hyperreactivity to epinephrine and hyperreactivity to other agonists

The unadjusted and adjusted Odds Ratios (probability of hyperreactivity to the specified agonist given hyperreactivity to epinephrine/probability of hyperreactivity to the specified agonist given no hyperreactivity to epinephrine) are shown for three different agonists. As expected, hyperreactivity to 0.4 μM epinephrine predicts hyperreactivity to 10 μM epinephrine. The dashed line indicates the position of an OR=1.0. Every bar represents an Odds Ratio that is significant at the <0.001 level.