Acute myocardial infarction (AMI) is myocardial necrosis due to severe and persistent acute ischemia in the corresponding myocardium as a result of a dramatic reduction or interruption of coronary blood supply based on coronary artery lesions. The key to treating myocardial infarction is to open the infarct-related artery as early as possible, completely and permanently, and restore effective myocardial reperfusion, which can significantly reduce the infarcted area, save cardiac function, prevent dilatation and expansion of the infarcted area, inhibit left ventricular remodeling, reduce serious complications and mortality and disability, and improve clinical prognosis.
For patients with acute myocardial infarction, myocardial necrosis starts to occur after 20 minutes of coronary occlusion, and most of the myocardium becomes necrotic in more than 6 hours, so it is crucial to open the infarct-related vessels as early as possible. The ideal reperfusion therapy must avoid delay and strive to perform thrombolysis within 30 minutes of the patient’s presentation and balloon dilation within 90 minutes.
In recent years, a large body of evidence-based medicine has shown that direct percutaneous coronary intervention (PCI) is more effective than intravenous thrombolytic therapy in achieving therapeutic goals and in reducing mortality, reinfarction, intracranial hemorrhage, and infarct-related arterial reocclusion rates.
Patients with acute myocardial infarction should be initiated immediately upon arrival at the hospital with an in-hospital green channel to transfer patients to the catheterization laboratory as soon as possible, requiring a door-capsule time of <90 minutes. Later, we should aim to open the vessel from FMC (first pre-hospital medical contact) to balloon dilation within 60 min according to the latest international standard.
It requires a group of medical and nursing staff with complete technical strength, good working attitude and collaboration spirit to be able to handle various emergencies in a timely and proficient manner during and after surgery, and requires interventionalists to operate at any time 24 hours a day and the catheterization laboratory to be open 24 hours a day to respond to patients with acute myocardial infarction at any time and to establish a standardized pathway for acute myocardial infarction rescue.
Pathway I.
Patients with acute ST-segment elevation myocardial infarction diagnosed outside the hospital can be notified by phone to the interventionalist to activate the catheterization laboratory and send the patient directly to the catheterization laboratory;
Route 2.
Patients with out-of-hospital confirmed acute ST-segment elevation myocardial infarction who cannot be sent directly to the catheterization laboratory should be given oxygen, open intravenous access, and cardiac and blood pressure monitoring in the intensive care unit; coronary angiography should be started as soon as possible after the arrival of the catheterization laboratory team.
Pathway three.
Upon arrival of an undiagnosed patient, the first physician must complete the first ECG and obtain blood for myocardial injury markers within 10 minutes. Immediately after diagnosis, open intravenous access, administer oxygen monitoring, and initiate emergency PCI treatment procedures. The catheterization unit team should arrive at the hospital within 30 minutes.
1. Direct PCI (percutaneous coronary intervention)
The Ministry of Health clinical pathway for acute ST-segment elevation myocardial infarction specifies the following as the preferred indications.
① All patients seen in hospitals with emergency PCI conditions, with onset <12 hours; especially those with onset >3 hours;
② High-risk patients. Patients with cardiogenic shock, but AMI <36 hours and shock <18 hours, especially those with onset time >3 hours;
(iii) Patients with contraindications to thrombolysis;
④Patients with a high suspicion of STEMI.
2.Transfer PCI
(1) If the patient is seen in a hospital without emergency PCI, if the expected time between first medical contact (FMC) and balloon dilation is less than 2 hours, the patient should be transferred to a hospital with emergency PCI for direct PCI after antithrombotic treatment. If the expected time delay is >2 hours (>90 minutes for patients aged <75 years with extensive anterior wall myocardial infarction), patients should receive thrombolytic therapy in situ and be transported to a hospital with PCI access for PCI within 3-24 hours.
(2) Patients with high-risk STEMI seen in hospitals without direct PCI, especially those with contraindications to thrombolysis or those without contraindications to thrombolysis but with >3 h of onset, may be transported to a hospital where PCI is feasible as soon as possible while on antithrombotic (antiplatelet or anticoagulation) therapy.
(3) Patients with low-risk STEMI with persistent symptoms after thrombolysis and suspected failure of thrombolysis should be transferred as soon as possible to a hospital where emergency PCI is feasible after intravenous thrombolysis, and if necessary, PCI or appropriate drug therapy should be performed.