[Risk factors of early myocardial injury and the impact of early myocardial injury on prognosis of patients with extensive burns].

Objective: To analyze the risk factors of early myocardial injury and the impact of early myocardial injury on prognosis of patients with extensive burns. Methods: A retrospective case series study was conducted. From January 2018 to August 2022, 361 patients with extensive burns who met the inclusion criteria were admitted to Tongren Hospital of Wuhan University & Wuhan Third Hospital, including 231 males and 130 females, aged 50 (36, 58) years, with total burn area of 45% (35%, 60%) total body surface area. According to the highest level of creatine kinase isoenzyme-MB (CK-MB) within 72 h post injury, the patients were divided into early myocardial injury group (CK-MB≥75 U/L, 182 patients) and non-early myocardial injury group (CK-MB<75 U/L, 179 patients). The following data of patients in the 2 groups were collected and analyzed, including gender, age, total burn area, admission time post injury, combination with shock on admission, combination with inhalation injury on admission; the main blood test indexes such as myocardial enzyme spectrum, blood routine, liver and kidney function, and electrolytes within 72 h post injury; and treatment outcomes and fatality rate. Data were statistically analyzed with chi-square test, independent sample t test, or Mann-Whitney U test. The multivariate logistic regression analysis was conducted to screen the independent risk factors for early myocardial injury and for death in patients with extensive burns. Results: There were statistically significant differences in gender, combination with shock on admission, total burn area, and admission time post injury of patients between the two groups (with χ² values of 6.40 and 6.10, Z values of 5.41 and 3.03, respectively, P<0.05). There were no statistically significant differences in age, combination with inhalation injury on admission of patients between the two groups (P>0.05). The CK-MB, creatine kinase, lactate dehydrogenase, α-hydroxybutyrate dehydrogenase, white blood cell count, neutrophil-to-lymphocyte ratio (NLR), alanine aminotransferase (ALT), aspartate aminotransferase, potassium, and hemoglobin within 72 h post injury were significantly higher than those in non-early myocardial injury group (with Z values of 15.40, 6.26, 7.59, 7.02, 2.64, 4.53, 4.07, 6.32, and 4.12, t=2.34, respectively, P<0.05), while the level of calcium was significantly lower than that in non-early myocardial injury group (Z=2.72, P<0.05). There were no statistically significant differences in other blood test indexes of patients between the two groups (P>0.05). The total burn area, admission time post injury, NLR and ALT within 72 h post injury were the independent risk factors for early myocardial injury in patients with extensive burns (with odds ratios of 1.03, 1.07, 1.04, and 1.02, 95% confidence intervals of 1.02-1.05, 1.00-1.11, 1.02-1.07, and 1.00-1.03, respectively, P<0.05). The fatality rate of patients in early myocardial injury group was 8.8% (16/182), which was significantly higher than 2.8% (5/179) in non-early myocardial injury group (χ² =5.93, P<0.05). Early myocardial injury, age, combination with shock on admission, and combination with inhalation injury on admission were the independent risk factors for death in patients with extensive burns (with odds ratios of 3.60, 1.04, 6.53, and 3.14, 95% confidence intervals of 1.17-11.05, 1.01-1.07, 1.39-30.68, and 1.15-8.56, respectively, P<0.05). Conclusions: The total burn area, admission time post injury, NLR and ALT within 72 h post injury were the independent risk factors for early myocardial injury in patients with extensive burns. Patients with extensive burns with early myocardial injury have a higher fatality rate, and early myocardial injury is an independent risk factor for the patients' death.