Aims Platelet indices have been associated with traditional cardiovascular risk factors, cardiovascular diseases and all-cause mortality. This study aimed to investigate the role of platelet count, mean platelet volume (MPV) and platelet-to-leukocyte ratio, including platelet-to-monocyte and platelet-to-lymphocyte ratio with cardiac function, heart failure (HF) phenotypes and clinical outcome, worsening of HF. Methods and results Univariate and multivariable linear and Cox regression analyses were used to investigate the associations between platelet indices, cardiac function and worsening of HF in 3250 subjects enrolled in the MyoVasc study. Higher MPV, lower platelet count, lower platelet-to-leukocyte and platelet-to-monocyte ratios have been associated with reduced left ventricular ejection fraction (beta estimate [β] MPV [fL] = À0.05 [À0.09; À0.02], β platelet count (× 10/L) 9 = 3.4 [1.2; 5.6], β platelet-to-leukocyte ratio = 1.4 [1.1; 1.8], β platelet-to-monocyte ratio = 28 [20; 36]) and increased E/E' ratio (β MPV [fL] = 0.04 [0.003; 0.07], β platelet count (× 10/L) 9 = À3.1 [À5.3; À0.92], β platelet-to-leukocyte ratio = À0.83 [À1.2; À0.46], β platelet-to-monocyte ratio = À20 [À28; À12]), independent of age and sex. Cox regression demonstrated an increased risk for worsening of HF in subjects with MPV > 75th percentile (hazard ratio [HR] = 1.47 [1.16; 1.87]), platelet count < 25th percentile (HR = 1.36 [1.07; 1.74]), platelet-to-leukocyte < 25th percentile (HR = 1.53 [1.20; 1.95]), platelet-to-monocyte < 25th percentile (HR = 1.38 [1.08; 1.77]) and platelet-to-lymphocyte > 75th percentile (HR = 1.50 [1.17; 1.93]) ratios, independent of potential confounders. MPV > 75th percentile and platelet count < 25th percentile were strongly related to outcome in HFpEF vs. HFrEF (P for difference = 0.040). Platelet-to-leukocyte ratios were associated with worse outcome in both HF phenotypes, without a significant difference between HFpEF and HFrEF. Conclusions Platelet indices are linked with worse cardiac function and adverse clinical outcome, independent of subjects' underlying cardiovascular profile. This study emphasizes their important value to provide additional information on pathophysiology and risk stratification in HF syndrome.

Background: Heart failure (HF) is a multifactorial syndrome with pathophysiological complexities still not fully understood. Higher mean platelet volume (MPV), a potential marker of platelet activation, and high concentrations of parathyroid hormone (PTH) have been implicated in the pathogenesis of HF.Aim: This study aims to investigate sex-specifically the association between PTH concentrations and platelet indices in phenotypes of HF.Methods and Results: PTH and platelet indices (MPV and platelet count) were available in 1,896 participants from the MyoVasc study in Mainz, Germany. Multivariable linear regression models, adjusted for age, sex, season, vitamin D status, cardiovascular risk factors, comorbidities, estimated glomerular filtration rate, and medication, were used to assess the associations between platelet indices and PTH. The results showed distinct sex-specific associations between PTH and platelet indices. A positive association between PTH and MPV was found in females with symptomatic HF with reduced ejection fraction (HFrEF) only [β = 0.60 (0.19; 1.00)]. Platelet count was inversely associated with PTH in male HFrEF individuals [β = −7.6 (−15; −0.30)] and in both males and females with HF with preserved ejection fraction (HFpEF).Conclusion: This study reports differential, sex-specific relationships between PTH and platelet indices in HF individuals independent of vitamin D status and clinical profile. Particularly in phenotypes of symptomatic HF, distinct associations were observed, suggesting a sex-specific mechanism involved in the interaction between PTH and platelets.

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