Using a convenience sampling method, this study selected patients with CHF who were hospitalized in the cardiovascular department of a tertiary hospital from March 2023 to December 2023 as the research subjects. Inclusion Criteria: (1) Patients diagnosed with CHF by attending physicians or higher, based on the diagnostic criteria outlined in the ‘2018 Chinese Guidelines for the Diagnosis and Treatment of Heart Failure’ (24). Patients classified as New York Heart Association (NYHA) functional class II to IV according to the American College of Cardiology's classification requirements. (2) Patients aged 18 years or older. (3) Patients who provided informed consent and voluntarily agreed to participate in this study.Exclusion Criteria: (1) Patients with severe wasting diseases or malignant tumors. (2) Patients with mental disorders or communication difficulties. (3) Patients who have undergone heart transplantation. Sample Size Estimation: Based on Kendall's sample size calculation method, the number of samples selected should be 5–10 times the number of study variables (25), with a minimum sample size of 135 cases. Considering potential invalid or missing questionnaires during the data collection process, a 20% increase in the sample size was applied, resulting in a final collection of 200 valid questionnaires, based on the annual hospitalization rate of CHF patients at the hospital.

The questionnaires were distributed on-site, accompanied by standardized instructions guiding patients to complete them independently. Upon completion, the questionnaires were collected for verification to ensure their completeness and validity. A total of 210 questionnaires were distributed, with 200 valid responses collected, resulting in an effective response rate of 95.2%.

SPSS 26.0 software was used for statistical analysis. The study variables (health literacy, symptom burden, social support, and coping styles) were continuous numerical variables that conformed to a normal distribution. Descriptive analysis was presented using the mean and standard deviation; otherwise, the median and interquartile range were reported. Correlation analysis was conducted using Pearson correlation. Mediation analysis was performed using the Process plugin in SPSS, employing bootstrap methods to test the significance of the mediation effect. If the confidence interval of the test results did not include 0, this indicated a significant mediation effect; conversely, if the interval included 0, the mediation effect was considered not significant.

Among 200 patients with CHF, there were 113 male patients (56.5%) and 87 female patients (43.5%). Patients aged 70 years and older numbered 97 (48.5%), those aged 46–69 years totaled 91 (45.5%), and 12 patients (6.0%) were aged 18–45. A total of 163 patients were married (81.5%), and 118 patients (59%) had an education level of elementary school or junior high school or lower, while 39 patients (19.5%) had a college degree or higher. Eighty-two patients (41%) reported an average monthly income of over 5,000 yuan. The living situation indicated that 146 patients (73%) resided in urban areas, and 108 patients (54%) cohabited with children, spouses, or parents. There were 135 patients (67.5%) covered by health insurance. In terms of heart function classification, 113 patients (56.5%) were classified as New York Heart Association (NYHA) Class II, 66 patients (33%) as Class III, and 21 patients (10.5%) as Class IV. 105 patients (52.5%) had a Body Mass Index (BMI) of 24 kg/m² or greater, and 153 patients (76.5%) had preserved ejection fraction. A total of 111 patients (55.5%) had one to two comorbidities, and 79 patients (39.5%) had undergone health examination every one to two years. Additionally, 94 patients (47%) self-reported normal or average daily salt intake, while 124 patients (62%) did not engage in regular exercise (Table 1).

In this study, the symptom burden score of CHF patients was 0.73 ± 0.45, the health literacy score was 29.38 ± 9.76, the social support score was 59.15 ± 10.58, the facing coping style score was 19.45 ± 5.53, the avoidance coping style score was 12.78 ± 4.62, and the yielding coping style score was 9.18 ± 4.13 (Table 2).

The results of pearson correlation analysis showed that the symptom burden scores of CHF patients in this study were closely related to health literacy, social support, and coping style scores. Among them, the health literacy of patients was significantly negatively correlated with the symptom burden score (r = −0.557, P < 0.01), social support was significantly negatively correlated with the symptom burden score (r = −0.680, P < 0.01), and the yielding coping style was significantly positively correlated with the symptom burden score (r = 0.774, P < 0.01). In addition, the health literacy of CHF patients was significantly positively correlated with the social support score (r = 0.597, P < 0.01), and was significantly negatively correlated with the yielding coping style score (r = −0.646, P < 0.01), at the same time, the social support of CHF patients was significantly negatively correlated with the yielding coping style score (r = −0.718, P < 0.01) (Table 3).

With the health literacy of CHF patients as the independent variable, symptom burden as the dependent variable, social support and yielding coping style as the mediating variables, a chain mediation effect model was constructed (Figure 1), and the model 6 in the process plug-in was used for analysis and testing (Table 4).

Health literacy of CHF patients can significantly positively predict social support, with a coefficient of 0.646 (95% CI: 0.524, 0.768), and significantly negatively predict the yielding coping style, with a coefficient of −0.143 (95% CI: −0.190, −0.095), but has no significant effect on symptom burden, with a coefficient of −0.002, P > 0.05, 95% CI is (−0.007, 0.003), including 0. Social support can significantly negatively predict the yielding coping style, with a coefficient of −0.202 (95% CI: −0.246, −0.158), and significantly negatively predict the symptom burden, with a coefficient of −0.010 (95% CI: −0.016, −0.005), the yielding coping style can significantly positively affect the symptom burden of CHF patients, with an impact coefficient of 0.062 (95% CI: 0.048, 0.077).

The mediating effect of CHF patients’ health literacy on symptom burden through social support is −0.007. The Bootstrap test shows that the 95% CI is (−0.011, −0.003), which does not include 0, proving that the mediating effect is significant; the effect of CHF patients health literacy on symptom burden through yielding coping style is −0.009. The Bootstrap test shows that the 95% CI is (−0.013, −0.006), which does not include 0, proving that the mediating effect is significant, the chain mediating effect of CHF patients’ health literacy on symptom burden through social support and yielding coping style is −0.008. The Bootstrap test shows that the 95% CI is (−0.011, −0.006), which does not include 0, proving that the chain mediating effect is significant (Table 5).

In this study, among the three dimensions of symptom burden in patients with CHF, the heart failure symptom dimension scored the highest, consistent with the findings of domestic scholar Xu Xiaohua (30). This indicates that a majority of CHF patients experience typical heart failure symptoms, primarily related to cardiac dysfunction. The psychological symptom dimension received the next highest score, which may be attributed to the generally low educational level of CHF patients, lack of proper health guidance, and the chronic nature of their illness. Research by international scholars, including Strangl (31) also found that CHF patients commonly experience various negative psychological symptoms, which impact their quality of life. In contrast, the physiological symptom dimension score in this study was lower than that reported by Xu Xiaohua, primarily because 56.5% of the 200 study participants had a heart function classification of II, with a majority having preserved ejection fraction. In Xu Xiaohua's study, however, a greater proportion of participants had heart function classifications of III (64.04%) and IV (10.86%), with over half (51.69%) exhibiting reduced ejection fraction. This further suggests that the symptom burden in CHF patients may be significantly correlated with their functional classification and ejection fraction levels.

In this study, the health literacy score of patients with CHF was 29.38 ± 9.76, which is similar to the findings of domestic researchers Zheng Zhanzhan (32), but lower than those reported by Japanese scholars Matsuoka (27). This discrepancy may be attributed to the fact that 59% of the participants in this study had an education level of junior high school or below, indicating generally low educational attainment, and a higher proportion of elderly individuals aged over 70. Due to declines in physiological function and cognitive abilities, older adults often have a poor understanding of their health conditions. Coupled with their limited educational background, this leads to inadequate comprehension of health information related to heart failure, thereby affecting the overall health literacy level of these patients. Furthermore, the results of this study indicate that the interactive health literacy dimension scored relatively high among CHF patients, followed by functional health literacy, with the critical health literacy dimension scoring the lowest. This finding is consistent with several domestic studies (33, 34). It suggests that CHF patients are more inclined to acquire health information through interaction and communication with others. This emphasizes the importance for healthcare providers to enhance verbal communication and educational efforts with patients in clinical settings, aiding them in accessing more health information. In contrast to the first two dimensions, critical health literacy imposes higher demands on patients. Therefore, it is crucial for healthcare professionals to ensure that health education for CHF patients is not merely about imparting information. Instead, it should focus on guiding and encouraging patients to apply critical thinking skills in analyzing health information, enabling them to make informed health decisions that are appropriate to their individual circumstances.