This study is a randomized, controlled clinical trial. Evaluation of microcirculation resistance by index of microcirculation resistance to explore the protective effect of Shexiang Tongxin dripping pills on microcirculation in patients with acute anterior myocardial infarction.

Percutaneous coronary intervention (PCI) is the best way to improve the prognosis of patients with acute myocardial infarction (AMI), and ischemia-reperfusion injury (I/R) can damage the vascular endothelium through complex mechanisms, leading to microcirculation dysfunction and aggravation myocardial damage and affect the prognosis. Cell and animal experiments have proved that Shexiang Tongxin Dropping Pill has anti-inflammatory, anti-oxidant, reducing I/R damage, reducing infarct size, improving peripheral muscle microcirculation, and improving coronary slow blood flow, but it lacks directive evidences of improved coronary microcirculation in AMI patients. The microcirculation resistance index (IMR) is a parameter to evaluate the microcirculation state obtained by the pressure/temperature guidewire during PCI, which can accurately and quantitatively reflect the patient's coronary microcirculation state. In this study, patients with acute anterior wall elevation ST-segment myocardial infarction (STEMI) who were prospectively selected for direct PCI treatment were randomly divided into treatment group and control group. The treatment group was given Shexiang Tongxin Dropping Pills before PCI and received direct PCI treatment, the control group only received direct PCI treatment. The IMR of the two groups was detected immediately after PCI, and the differences in IMR values, myocardial injury markers and cardiac function parameters between the two groups were analyzed. It is hoped to prove that Shexiang Tongxin dripping pills have coronary microcirculation protection in acute anterior wall elevation ST-segment myocardial infarction with undergoing direct PCI treatment, and the effect is rapid, so as to provide a basis for optimizing AMI treatment strategies.

Inclusion Criteria:

• Age ≥ 18 years old, no gender limit;
• Anterior wall STEMI within 12 hours of onset (diagnostic criteria: ischemic chest pain lasting ≥30min; ST-segment elevation or new left bundle branch block in two or more adjacent leads on the ECG; with or without Elevated myocardial markers), emergency PCI treatment is planned;
• Infarct-related coronary vascular anatomy is suitable for PCI treatment;
• Agree and cooperate to participate in this research, and sign an informed consent form

Exclusion Criteria:

• Past history of myocardial infarction history;
• The arteries related to infarction have received PCI in the past;
• Past CABG history;
• Killip grade of cardiac function ≥ grade III or cardiogenic shock;
• Systolic blood pressure ≤90mmHg;
• Bradycardia, heart rate <60 beats/min, or atrioventricular block of degree II or more;
• Allergic to Shexiang Tongxin Dropping Pills
• Past history of asthma or severe COPD;
• Severe liver and kidney dysfunction;
• Participate in other clinical trials within 3 months;
• Pregnancy or breastfeeding.