Association between Mean Platelet Volume and Autonomic Nervous System Functions: Increased Mean Platelet Volume Reflects Sympathetic Overactivity

Abstract

Aim: Increased mean platelet volume (MPV) may reflect increased platelet activation and accepted as an independent coronary risk factor. Adrenergic system has effects on platelet activation and thrombocytopoiesis. In this study, we assessed the effects of autonomic nervous system activity on MPV in patients with acute myocardial infarction (MI). Materials and Methods: Forty-seven patients with acute anterior MI were compared with 32 patients having normal coronary arteries. All patients underwent heart rate variability analysis by 24-h holter monitoring and blood samples were taken for MPV measurements during day and night times during holter monitoring. Results: Mean heart rate (HR), Low frequency (LF), LF/High frequency (HF) ratio, MPV were higher, standard deviation of all NN intervals (SDNN), root mean square of successive differences (RMSSD), the number of NN intervals that differed by more than 50 ms from adjacent interval divided by the total number of all NN intervals (PNN50), HF and platelet counts were lower in the patients with anterior MI compared to the control group. Day time LF, LF/HF, and MPV were significantly higher and HF were significantly lower compared to those measured during night time in both groups. Pearson's correlation analysis showed that MPV was positively correlated with ventricle score, degree of left anterior descending artery stenosis, mean HR, LF, LF/HF, and negatively correlated with SDNN, HF, and platelet count. Multivariate analysis revealed that MPV was affected by ventricle score and LF/HF ratio. Conclusions: MPV is significantly higher in the patients with MI and MPV in both groups shows great diurnal and nocturnal variation that is attributed to the alterations in the autonomic nervous system. We suggest that prognostic role of increased MPV in patients with MI are closely associated with increased sympathetic activity and decreased heart rate variability in these patients.