Platelet and Leukocyte Mitochondrial Function With Cardiac Function and Self-Reported Health Status Among Obese Patients With Heart Failure

BACKGROUND: Mitochondrial dysfunction plays a key role in the development of heart failure (HF), including HF with reduced ejection fraction (HFrEF) and HF with preserved ejection fraction (HFpEF). Impaired mitochondrial function negatively affects cardiac function and, subsequently, the health status of patients. However, measuring mitochondrial function in human myocytes is difficult because of the high risk associated with myocardial biopsy. Platelets and leukocytes have functional mitochondria and can potentially serve as a surrogate for myocardial mitochondria. Roles of platelet and leukocyte mitochondrial function in HF have not yet been fully explored. OBJECTIVE: We aimed to explore the relationships of platelet and leukocyte mitochondrial function with cardiac function and self-reported health status among obese patients with HF and examine if the relationships vary between HFrEF and HFpEF. METHODS: Forty-five obese patients with HF were recruited. Maximal enzymatic activities (Vmax) of platelet cytochrome c oxidase (COX) and citrate synthase (CS) were assessed. Leukocyte mitochondrial mass, membrane potential, superoxide production, and apoptosis were measured in a subset of the sample. Data on cardiac function were retrieved from electronic health records. Self-reported health status was assessed using the Kansas City Cardiomyopathy Questionnaire (KCCQ). Pearson correlations were performed. RESULTS: Platelet COX Vmax was negatively correlated with left ventricular end-systolic diameter. Positive correlations of leukocyte mitochondrial mass and superoxide production with left ventricular mass and mass index were observed, respectively. Leukocyte mitochondrial mass and superoxide production also negatively correlated with KCCQ summary scores. These relationships varied between HFrEF and HFpEF. DISCUSSION: Platelet and leukocyte mitochondrial function was found to significantly correlate with some echocardiographic parameters and KCCQ scores. These findings provided preliminary data to support future research to further explore the potential of using platelets and leukocytes as surrogate biomarkers. Identifying easy-accessible mitochondrial biomarkers will be useful for assessing mitochondrial function to assist with early diagnosis and monitoring the effectiveness of mitochondrial-targeted therapy in HF patients.