Blood Platelet Count at Hospital Admission Impacts Long-Term Mortality in Patients with Acute Coronary Syndrome.

INTRODUCTION

Platelets play a fundamental role in the pathogenesis of acute coronary syndrome (ACS). The platelet count (PC) at hospital admission is easy to obtain, but whether thrombocytopenia or/and thrombocytosis impact long-term mortality (LTM) after ACS is unclear.

OBJECTIVE

To evaluate the effect of PC at hospital admission on LTM in patients with ACS.

METHODS

This retrospective cohort study included patients with the ICD-10 codes for unstable angina (I.20) and acute myocardial infarction (I.21, I.22). Thrombocytopenia was defined as a blood PC <150 G/L and thrombocytosis as a PC >450 G/L. Additional platelet indices which were tested included plateletcrit (PCT), the mean platelet volume (MPV), the platelet distribution width (PDW), and the platelet larger cell ratio (P-LCR). Data on all-cause death were obtained from the National Health Fund database.

RESULTS

The study included 3,162 patients with a median follow-up of 27.2 months (interquartile range 12.5-46.8 months; max 68.7 months). Patients with thrombocytopenia and thrombocytosis yielded a higher maximal analyzed 5-year mortality rate in comparison with normal PC patients (45.8 and 47.7 vs. 24.2%, respectively; p < 0.00001) which was mainly driven by higher deaths at 1-2 years after ACS. The 5-year LTM was also significantly higher in patients with abnormal PCT and MPV levels in comparison with patients with PCT and MPV within the normal range. Other platelet indices (PDW, P-LCR) were not associated with a worse outcome. The Cox proportional hazards model revealed that thrombocytopenia at admission was independently associated with higher LTM after ACS (RR 1.83; 95% CI 1.1-3.0; p = 0.01).

CONCLUSIONS

Both thrombocytopenia and thrombocytosis at hospital admission in post-ACS patients are associated with a significant almost two times higher 5-year mortality rate.