The Impact of Fexofenadine Hydrochloride on the Prognosis of Patients Post-Acute Myocardial Infarction

Inclusion Criteria: * Age ≥ 18 years old. * Able to verbally confirm understanding of the trial risks, benefits, and treatment options of fexofenadine hydrochloride therapy. He/she or his/her legal representative must provide written informed consent prior to participating in the clinical trial. * Acute ST-segment elevation myocardial infarction (STEMI) occurring within 7 days, with diagnostic criteria including: i) Typical clinical symptoms: such as severe crushing pain in the retrosternal or precordial area, usually lasting more than 10-20 minutes, which may radiate to the left upper arm, jaw, neck, back, or shoulders, etc.; ii) Elevated serum cardiac troponin (cTn): at least one measurement above the upper limit of normal (99th percentile of the reference upper limit); iii) ST-segment elevation: new ST-segment elevation at the J point in 2 adjacent leads. * Echocardiography indicating segmental wall motion abnormalities. Exclusion Criteria: * Need for long-term use of fexofenadine hydrochloride or other H1 receptor inhibitors. * Previous coronary artery bypass grafting (CABG) surgery. * History of severe renal failure with estimated glomerular filtration rate (eGFR) \< 30 ml/min. * History of severe liver dysfunction. * History of concurrent severe infection, hepatobiliary obstruction, or malignant tumor. * Expected life expectancy of less than 2 years due to non-cardiac diseases. * Currently receiving immunosuppressive therapy. * Pregnant, potentially pregnant, or lactating women. * Contraindication to the study drug or examinations. * Failure to provide written informed consent. * Presence of mechanical complications (ventricular septal defect, papillary muscle dysfunction, acute mitral regurgitation), refractory cardiogenic shock unresponsive to vasopressors, acute left heart failure or pulmonary edema, or malignant arrhythmias uncontrolled by antiarrhythmic drugs at enrollment.