Life-or-death situations in acute coronary syndrome: Recognition of unstable angina, warning signs of myocardial infarction, and early self-help.

Myocardial infarction and unstable angina. 1. New disease classification for guiding treatment. A new term, "acute coronary syndrome," is frequently heard, encompassing myocardial infarction and unstable angina (formerly known as pre-infarction syndrome). It represents an urgent and critical clinical condition. This group of diseases is characterized by rapid onset, rapid changes, and a high mortality rate, but is treatable. Clinically, acute coronary syndrome should be considered in cases of first-time angina attacks, angina at rest, nocturnal angina, worsening angina, or decreased effectiveness of sublingual nitroglycerin. Emergency assessment and treatment are necessary.

The pathological basis of acute coronary syndrome (ACS) is the rupture of atherosclerotic plaques, triggering coagulation. Initially, a "white" thrombus, mainly composed of platelets, forms, leading to non-occlusive coronary blood flow obstruction. Depending on the severity, it manifests as unstable angina or non-Q wave myocardial infarction (ST-segment elevation acute coronary syndrome). Further progression causes red blood cell aggregation, transforming the "white" thrombus into a "red" thrombus, resulting in coronary artery occlusion and interruption of blood flow. Clinically, this presents as ST-segment elevation acute coronary syndrome, commonly known as acute myocardial infarction. Treatment for ST-segment elevation acute coronary syndrome is characterized by emergency thrombolysis and anticoagulation, aiming to open the occluded coronary artery within hours and achieve and maintain myocardial reperfusion. Treatment for ST-segment non-elevation acute coronary syndrome is characterized by non-thrombolytic anticoagulation, aiming to stabilize ruptured plaques within hours to days, allowing them to gradually heal and become stable. This involves managing risk factors (hypertension, hyperlipidemia, smoking, and diabetes) to prevent further plaque rupture. Therefore, the current classification of acute coronary syndromes aligns with the underlying pathological process of the disease and is beneficial in guiding patient treatment.

Traditional classification, for the convenience of the public in accessing medical care. For the purpose of popular science and to facilitate public identification and understanding, this chapter adopts the traditional classification: myocardial infarction and unstable angina, also known as "pre-infarction syndrome." The aim is to help the public recognize the dangerous symptoms of myocardial infarction, especially the warning signs before infarction, so as to seek medical attention, treatment, and rescue in a timely manner to achieve the best prevention and treatment results.

Unstable angina. 1. Understanding Unstable Angina. For the past 30 years, it has often been referred to as pre-infarction syndrome. According to recent classification methods, it belongs to a type of acute coronary syndrome with ST-segment non-elevation. These patients experience extremely rapid changes in their condition and are very prone to myocardial infarction or sudden death. However, with aggressive and appropriate treatment, the vast majority of cases can be controlled and treated. Therefore, increasing patient and public awareness, and early identification, diagnosis, and treatment are of great significance. The goal of timely detection, identification, and aggressive treatment of this disease is to stabilize ruptured plaque lesions within hours to days, allowing the ruptured plaque to gradually heal and become stable, while simultaneously managing risk factors (hypertension, hyperlipidemia, smoking, and diabetes) to prevent recurrence of plaque rupture.

Diagnostic points. (1) Symptoms. See the section on angina, but symptoms are often more severe. Unstable angina includes: ● worsening exertional angina; ● first-onset angina; ● post-infarction angina. (2) Examination. If the ST segment is not elevated on the electrocardiogram, there may be objective evidence of myocardial ischemia, such as: ● chest pain accompanied by ST segment depression ≥0.05mV on the electrocardiogram, or T wave changes related to chest pain, or pseudo-improvement of inverted T waves; ● history of acute myocardial infarction, PTCA, or coronary revascularization surgery; ● previous coronary angiography confirming the diagnosis of coronary heart disease; ● the difference between myocardial infarction without ST segment elevation and unstable angina lies in whether the CK-MB elevation is greater than or equal to twice the upper limit of normal, or whether there is TnT or TnI elevation. (3) Risk stratification. The severity of the condition is assessed based on the patient's medical history, symptoms, electrocardiogram, and laboratory tests. To determine the treatment strategy.

Principles of initial treatment: During the acute phase, bed rest, oxygen therapy, and continuous cardiac monitoring are recommended. ● Low-risk patients without recurrent angina, with no ischemic changes on ECG, and normal serum myocardial markers can be discharged after 24-48 hours of observation. ● Medium- and high-risk patients with elevated myocardial markers should have their hospital stay extended and receive enhanced medical treatment.

Acute myocardial infarction (also known as ST-segment elevation acute coronary syndrome). 1. Prodromal symptoms. Unstable angina is the most typical prodromal symptom before infarction. Some patients experience some prodromal symptoms before myocardial infarction. By understanding these prodromal symptoms, patients can be more vigilant and identify or prevent the occurrence and development of myocardial infarction as early as possible. (1) Chest discomfort after exertion. It occurs several days to several weeks before myocardial infarction and is similar to exertional angina, but it often occurs at rest or during mild activity. (2) Significant general malaise or fatigue before the onset of myocardial infarction. (3) First attack of angina, or previous angina, but this attack is prolonged, aggravated, lasts more than 15 minutes, or cannot be completely relieved by nitroglycerin.

Early self-help and key points of pre-hospital treatment. The key is to raise awareness and recognition of myocardial infarction and unstable angina to avoid delays. 1. Be alert to and recognize the symptoms of myocardial infarction. Patients should be alert to and recognize the symptoms of angina or acute coronary syndrome: chest pain or chest discomfort with or without radiating pain in the upper limbs, back, neck, jaw or upper abdomen, difficulty breathing, weakness, cold sweats, nausea, dizziness, and some may have nausea, vomiting, and the urge to defecate. 2. Immediately stop the activity that induces chest pain, rest immediately, relax, and if possible, lie down. According to the actual situation, the following should be done: (1) If coronary heart disease has never been found, but this is suspected to be a heart attack, and the symptoms do not improve or even worsen after 5 minutes, it is best to call 120 for emergency help and ask an ambulance instead of relatives or friends to transfer to the hospital. (2) For patients diagnosed with coronary heart disease, if during an attack they feel different from previous attacks, or their symptoms are worse, and they suspect a myocardial infarction: ● Aspirin 150-325mg (chewed); ● Sublingually administer one nitroglycerin tablet. If ineffective, administer another tablet. If symptoms do not improve after 5 minutes of medication, call 120 immediately. (3) For patients diagnosed with coronary heart disease, if during an attack, sublingually administering one nitroglycerin tablet significantly improves symptoms, and if tolerated, administer one tablet every 5 minutes for a total of 3 times; if there is no significant improvement, call 120 immediately.

Treatment. 1. General treatment. (1) Bed rest, eliminate tension and fear, continuous blood pressure and electrocardiogram monitoring; oxygen inhalation, establish intravenous access. (2) Relieve pain and stabilize emotions: Morphine 3-5mg intravenously, if necessary, repeat injection 1-2 times after 5 minutes. For those who have contraindications to morphine, meperidine 25-50mg intravenously can be used instead. 2. Drug treatment. (1) Thrombolytic therapy. It can only be used for patients with myocardial infarction. It is prohibited for patients with unstable angina. It includes urokinase, streptokinase, recombinant tissue plasminogen activator (rPA), etc. Indications: ECG shows ST segment elevation >0.1mV, or new bundle branch block on ECG, etc. Treatment should start within 12 hours after the onset of symptoms, age <75 years, and no contraindications to thrombolytic therapy. (2) Antiplatelet and antithrombin therapy. ● Antiplatelet therapy. Aspirin: 300 mg initially, reduced to 50-100 mg after 3-5 days, should be taken long-term; Clopidogrel: 300 mg initially, followed by 75 mg daily for maintenance, for at least 1 month; Combined use of aspirin and clopidogrel: It is recommended that all ACS patients use aspirin and clopidogrel in combination for the first 4-12 weeks. ● Antithrombin therapy: Low molecular weight heparin. (3) Nitrates. Nitroglycerin continuously infused for 24-48 hours. (4) β-blockers. Except for those with contraindications, it is recommended that all patients take β-blockers. Metoprolol 12.5-25 mg, twice daily; Bisoprolol 2.5-10 mg/day. (5) ACEIs and angiotensin II receptor antagonists (ARBs). Except for those with contraindications, it is recommended that all patients take ACEIs or ARBs. (6) Lipid-lowering drugs. Except for those with contraindications, it is recommended that all patients take them. Currently, there is an emphasis on strengthening lipid-lowering therapy, as it can improve vascular endothelial cells, stabilize atherosclerotic plaques, and inhibit platelet aggregation, thus benefiting the condition.