[Early differential diagnosis of acute myocardial infarction and acute myocarditis in young patients].

To explore the value of general information and rapid laboratory tests obtained from the emergency department in the early diagnosis and prevention of young patients with acute myocardial infarction and acute myocarditis, in order to prevent the disease from progressing to a critical stage. This study employs a retrospective observational study, compiling clinical data from young patients diagnosed with acute myocardial infarction or acute myocarditis who were admitted to the Department of Cardiology or Emergency Department of the Second Affiliated Hospital of Soochow University from January 2015 to September 2024. Demographic information and laboratory test results from both the outpatient and emergency departments were retrieved. The acute myocardial infarction group comprised 267 patients (257 males, 10 females) aged 23-44 ys, while the acute myocarditis group included 134 patients (93 males, 41 females) aged 18-44 ys. A comparative analysis of the clinical data between the two groups was conducted, encompassing variables such as age, gender, comorbidities, high-risk factors, emergency blood routine tests, high-sensitivity C-reactive protein levels, coagulation profiles, renal function tests, NT-proBNP levels, myocardial injury markers, electrocardiogram readings, blood pressure, and heart rate. The results showed that:Compared with the young myocarditis group, the myocardial infarction group was older (ys)[38(35, 42) 30(25, 37), =7 893, <0.001], more male [257(96.3%) 93(69.4%), ²=57.95, <0.001], more smoking [211(79.0%) 38(28.4%), ²=97.32, <0.001], drinking history [125(46.8%) 22(16.4%), ²=35.51, <0.001], family history of coronary heart disease [45(16.9%) 3(2.2%), ²=18.09, <0.001], hypertension [100(37.5%) 12(9.0%), ²=36, <0.001] and diabetes [42(15.7%) 4(3.0%), ²=14.27, <0.001]. Systolic blood pressure (mmHg)[126(114, 144) 119(101, 126), =11 389.50, <0.001], diastolic blood pressure (mmHg)[80(70, 93) 72(62, 81), =12 220.50, <0.001], total white blood cell count (10/L)[11.3(9.2, 14.1) 8.5(6.6, 11.2), =10 825.50, <0.001], hemoglobin (g/L)[157(147, 166) 143(129, 154), =9 404.50, <0.001], platelet count (10/L)[244(206, 297) 207(173, 253), =11 680, <0.001], uric acid (μmol/L)[380(315, 446) 347(265, 412), =14 805.50, 0.005], ST segment elevation [204(76.4%) 57(42.5%), ²=73.03, <0.001] and Q wave formation [76(28.5%) 17(12.7%), ²=12.47, <0.001] in ECG were higher than those in myocarditis group. The duration of onset (hs) [6(3, 25) 48(24, 73), =27911, <0.001], heart rate (beats/min)[82(74, 92) 92(78, 103), =22 347, <0.001], D-dimer (μg/ml)[0.23(0.17, 0.51) 0.61(0.30, 1.38), =25 806, <0.001], High-sensitivity troponin T/99th percentile upper reference limit [5(1, 36) 16(8, 39), =22 577, <0.001], NT-proBNP (pg/ml) [204(64, 644) 824(189, 4 043), =25 134, <0.001], C-reactive protein (mg/L)[6(3, 9) 24(6, 55), =26 349.50, <0.001] and body temperature (℃) [36.50(36.30, 36.60) 37.35(36.50, 38.50), =26 961, <0.001] were significantly lower than those in myocarditis group, the symptoms of chest pain in myocardial infarction group was significantly higher than those in myocarditis group [262(98.1%) 83(61.9%), ²=97.24, <0.001], and the history of prodromal infection [12(4.5%) 112(83.6%), ²=261.26, <0.001], syncope [11(4.1%) 18(13.4%), ²=11.53, <0.001] and shock [6(2.2%) 22(16.4%), ²=27.59, <0.001] in myocardial infarction group were significantly lower than those in myocarditis group. With acute myocardial infarction as the target outcome, 8 influencing factors selected by LASSO regression, and 5 independent influencing factors were found after multiple Logistic regression, those were age (=1.21, 95%: 1.12-1.31; <0.001), pre-infection (=0.02, 95%: 0.01-0.06; <0.001), body temperature (=0.37, 95%: 0.18-0.77; =0.008), chest pain (=26.75, 95%: 5.87-121.81; <0.001) and white blood cell count (=1.27, 95%: 1.12-1.44; <0.001). Younger age, high body temperature and pre-infection are independent predictors for acute myocarditis, while chest pain and elevated white blood cell count are independent predictors for acute myocardial infarction. The five influencing factors selected by multivariate logistic regression and their combined diagnostic model were subjected to ROC analysis. The AUC reached 0.969, sensitivity reached 0.940 and specificity reached 0.925. Calibration curve and decision curve analysis(DCA) demonstrate that the model possesses excellent clinical application value. In conclusion, age, chest pain, pre-infection, body temperature and white blood cell count were independent factors in distinguishing acute myocardial infarction and acute myocarditis in young people. The clinical differential diagnosis model based on 5 independent factors may has high efficiency and good clinical practicability.