The Relationship Between Changes in Mean Platelet Volume and Mortality in Non–ST-Segment Elevation Myocardial Infarction

Abstract

We would like to thank Celik et al for their interest in our article. 1 As stated in their letter, 2 we found that an increase in mean platelet volume (MPV) from baseline was associated with mortality in patients with non-ST-segment elevation myocardial infarction.Mean platelet volume is a useful prognostic marker in ischemic heart disease. [3][4][5] Moreover, it is a reflection of both proinflammatory and prothrombotic conditions. 6 Larger platelets, indicating an increased MPV, are functionally, metabolically, and enzymatically more active than smaller ones. 7 Mean platelet volume is measured by cell counters using impedance and optical effects. 8 Inappropriate blood sampling and storing may lead to the inaccurate measurements of MPV that is sensitive to the storage temperature and delays in processing. 6 Also, the difference in blood sample anticoagulation may change size of platelets. 6 Especially, time-dependent swelling of platelets can be observed in samples anticoagulated with ethylenediaminetetraacetic acid (EDTA), and this may cause a pseudo increase in MPV. 9 It has been shown that platelet swelling in test tubes can be reduced by rapid processing of blood sampling (within <1 hour) or using tubes with sodium citrate. 10,11 Also, adding MPV stabilizers in standard tubes may lessen an artificial increase in MPV. 12 Although we did not use sodium citrate tubes and MPV stabilizers for the measurement of MPV in our study, all the samples were analyzed within 1 hour of collection, thus minimizing the effects of EDTA on MPV.Platelet distribution width (PDW) is a measure of variation in the size of circulating platelets and an index of platelet activation. 13 It has been shown that PDW was independently associated with mortality in patients with acute coronary syndrome. 14 Bekler et al showed that there was a significant correlation between an increased PDW and severity of coronary artery disease in patients with acute coronary syndrome. 15 Measurements of PDW at admission and 24 hours after were not performed in our study.We agree that it would be useful to evaluate changes in MPV along with PDW in the predicting mortality in patients with acute coronary syndrome.