## 1 Introduction  
Heart failure (HF) signifies a clinical and pathophysiological condition explained by the impairment of the heart's pump function and represents a syndrome that leads to the inability of the heart to ensure the flow necessary for the tissue's metabolic needs [1]. According to the definition proposed in the European Guidelines for the diagnosis and treatment of HF in 2021, HF is a clinical syndrome that includes symptoms (e.g., dyspnea, fatigue) and signs (e.g., pulmonary congestion and or systemic congestion), and that is the consequence of a structural and/or functional cardiac abnormality which causes increased intracardiac filling pressures and or inadequate cardiac output at rest or during exercise [2]. Depending on the value of the left ventricular ejection fraction (LVEF), HF is subdivided into three categories [2]: HF with reduced LVEF (\(\leq\)40%), HF with medium-reduced LVEF (41-49%), and HF with preserved LVEF (\(\geq\)50%), additionally requiring the certification of structural and or functional abnormalities compatible with LV diastolic dysfunction, increased intracardiac filling pressures, or increased natriuretic peptides. From a clinical point of view, HF is subdivided into four functional classes according to the New York Heart Association, which are the functional classes I-IV NYHA [3]. Despite the many medical problems and medical discoveries, heart failure (HF) remains one of the most important and frequently occurring public health problems, with continued very high mortality and morbidity and high hospitalization rates, especially for elderly patients. Among the cardiovascular diseases, it remains the condition with the highest degree of disability in terms of quality of life. Although the methods of diagnosis and treatment are increasingly complex, the mortality and hospitalization rates remain very high, which implies the large consumption of financial resources. Identifying an indicator with a prognostic role in patients with HF could represent a salutary solution in the future, as it could identify patients with a negative prognosis, represented by recurrent decompensation, frequent hospitalization, or increased mortality. Alongside the classic prognostic factors reported in the medical literature (e.g., reduced LVEF, hyponatremia, renal dysfunction, anemia, increased levels of NT-pro BNP), a new parameter of interest that has not been greatly studied in terms of its prognostic relationship with incidence of HF, makes its entrance, namely, the mean platelet volume (MPV). Thus, our study focused on MPV as a possible prognostic factor in patients with HF. MPV is an indicator that expresses the volume of platelets, having a normal value of 7.2-11.7 fl, being a variable that accurately reflects the size of platelets [4]. Data from the medical literature reveal that platelets with a high platelet volume have a greater enzymatic and metabolic potential than those with a lower platelet volume, thus presenting an intense procoagulant status [5; 6]. Therefore, MPV has been found to be predictive of cardiovascular disease [7], to be a possible indicator of platelet reactivity, and to be a predictor of many other diseases [8]. The prognostic correlation between MPV and HF is poorly understood, and the mechanisms underpinning it are unclear. There are limited studies showing that platelet activity increases in patients with acute HF [9]. Regarding the current state of knowledge represented in the medical literature regarding MPV as a possible negative prognostic factor in HF patients, studies are limited, but five studies have been reported, including a study conducted by [PERSON] [10], a study conducted by [PERSON] [11], a study conducted by [PERSON] [12], a study conducted by [PERSON] [13], and a study conducted by [PERSON] et al. [14]. The study conducted by [PERSON] et al. [10] suggested that MPV could be an indicator of disease progression and clinical status in patients with acute HF. The study included 190 patients with acute HF and 129 without acute HF.