Mean platelet volume/platelet count ratio as a predictor of long-term mortality after non-ST-elevation myocardial infarction

Previous studies reported an association between elevated mean platelet volume (MPV) and post-myocardial infarction mortality. This study explores the association between long-term mortality after non-ST-segment elevation myocardial infarction (NSTEMI) and the peripheral blood platelet indices (i.e., the mean platelet volume (MPV), platelet count, and the MPV/platelet (MPV/P) ratio). Two physicians independently reviewed the data of 619 NSTEMI patients. The blood samples were drawn and analyzed within 1 h of admission, the second, and the last hospital days. Patients were stratified into equal tertiles according to the platelet count, MPV, and MPV/platelet ratio. The primary outcome, 4-year all-cause mortality, was compared among the platelet indices tertile models. According to MPV, platelet count, and MPV/platelet ratio tertile models, there was a trend of higher 4-year mortality for the lower and upper tertiles in comparison to the middle tertiles. However, only the admission MPV/platelet ratio tercile model was statistically significant for predicting the 4-year mortality. The mortality rate of the highest MPV/platelet (48/207 (23%)) and the lowest (41/206 (20%)) tertiles were significantly higher than the middle tertile (19/206 (9%)), p = 0.0004 by the chi-squared test. After adjusting for Global Registry of Acute Coronary Events, the patients in the combined first and third MPV/P tertiles had higher mortality in reference to those in the middle MPV/P tercile (hazard ratio 1.951, confidence interval 1.032-3.687, and p < 0.0396). Our novel finding is that the MPV/platelet ratio is superior to the MPV alone in predicting long-term mortality after NSTEMI. We suggest that using this ratio will magnify any existing relationship between platelet indices and mortality post-NSTMI. Further studies are needed to confirm our finding.