A Comprehensive Guide to Coronary Artery Disease and Angina: From Identifying Typical Symptoms to Integrated Prevention and Treatment Strategies for Myocardial Infarction

Angina pectoris is a clinical syndrome characterized by discomfort in the chest, jaw, shoulder, back, or arm, caused by transient myocardial ischemia. Angina often occurs in patients with at least one major branch of the coronary artery having a stenosis of more than 50% in its lumen diameter. When experiencing physical or mental stress, the coronary blood flow cannot meet the metabolic needs of the myocardium, leading to myocardial ischemia and triggering an angina attack. Rest or sublingual nitroglycerin can relieve the symptoms. Additionally, some patients may have "normal" coronary angiography, but due to coronary artery spasm or endothelial dysfunction leading to myocardial ischemia, they may also experience angina. Non-coronary atherosclerotic heart disease can also present as angina, requiring differential diagnosis. Examples include valvular heart disease (especially aortic valve disease), hypertrophic cardiomyopathy, poorly controlled hypertension, hyperthyroidism, and severe anemia. Certain non-cardiac diseases, such as esophageal, chest wall, or lung diseases, can also cause similar angina symptoms and should be carefully differentiated.

(I) Clinical manifestations and diagnostic points. A diagnosis can be made if the patient has a typical medical history. 1. Typical angina pectoris has four basic characteristics: (1) Location of pain: mainly in the sternal body, precordial region, and anterior chest, with unclear boundaries, often radiating to the left shoulder, back, inner side of the left arm, left ring and little fingers, or neck, throat, jaw, etc. (2) Relationship between pain and exercise: physical labor, emotional excitement, and overeating are common triggering factors. The characteristic of angina pectoris is that the attack often occurs during exercise, rather than after exercise. (3) Characteristics and duration of pain: mostly squeezing pain or discomfort in the anterior chest, and the patient will often unconsciously stop the original activity until the symptoms are relieved. The pain generally lasts for 3-5 minutes and is relieved after stopping the activity. (4) Nitroglycerin is effective and relieves the pain within a few minutes after sublingual administration. If the patient has the first two of the four typical basic symptoms, a diagnosis of chronic angina pectoris can be made.

Atypical symptoms are more common than typical symptoms. Studies have shown that 80% of patients with myocardial infarction are unaware that they have coronary heart disease upon admission. One of the important reasons why patients are unaware that they have coronary heart disease is that many patients have atypical symptoms or even no symptoms, especially the elderly and diabetic patients, thus delaying treatment. Common atypical symptoms include: (1) Location of pain: not in the chest, but manifested as pain in the upper abdomen, jaw, toothache, neck pain, shoulder and back pain, and even leg pain; (2) No pain: 15%-30% of the elderly, especially diabetic patients, are painless; (3) Duration: either short or long; (4) Non-painful: manifested as chest tightness, shortness of breath, unexplained discomfort, difficulty breathing, syncope, etc.; (5) Accompanied by gastrointestinal symptoms, misleading patients and medical staff: for example, upper abdominal pain accompanied by nausea, vomiting, and diarrhea is easily confused with gastroenteritis, cholecystitis, etc. Therefore, patients with cardiovascular and cerebrovascular risk factors, such as hypertension, diabetes, and hyperlipidemia, should be alert to atypical angina symptoms and seek medical attention promptly.

(II) Types of Angina Pectoris. 1. Chronic Stable Angina Pectoris: This type of angina is characterized by stable plaques and a stable condition. The severity, frequency, nature, and triggering factors of attacks do not change significantly over several weeks. 2. Unstable Angina Pectoris: This type of angina pectoris is caused by unstable atherosclerotic plaques, leading to intraplaque hemorrhage, rupture, platelet aggregation, thrombus formation, or a sudden worsening or occlusion of blood vessels due to vasospasm, resulting in myocardial ischemia and angina. Unstable angina pectoris can easily develop into myocardial infarction or sudden death, requiring immediate risk assessment. 3. Exertional Angina Pectoris: This type of angina pectoris is triggered by exercise, emotional excitement, a large meal, cold weather, heavy smoking, or other conditions that significantly increase myocardial oxygen demand. Based on its characteristics, it can be divided into: stable exertional angina pectoris; newly onset exertional angina pectoris; and worsening exertional angina pectoris. 4. Spontaneous Angina Pectoris: This type of angina pectoris is not significantly related to physical exertion, emotions, or other triggering factors that increase cardiac activity. Angina pectoris occurs at rest and is caused by coronary artery spasm. 5. Mixed angina: Patients experience both exertional and spontaneous angina attacks simultaneously. 6. Post-infarction angina: Angina pectoris that occurs within one month after a myocardial infarction, indicating significant stenosis in the coronary arteries.

(III) Differential diagnosis of chest pain. Many diseases can cause chest pain, which must be distinguished from angina pectoris caused by coronary heart disease. It should also be noted that some chest pains are relieved by sublingual nitroglycerin, but not all of them are angina pectoris, such as esophageal spasm, reflux esophagitis, etc. 1. Non-cardiac diseases: (1) Digestive system: esophageal diseases, esophageal motility disorders, biliary tract diseases, peptic ulcer diseases, pancreatic diseases. (2) Chest wall diseases: costochondritis, costochondritis, herpes zoster, cervical and thoracic spondylosis, etc. (3) Lung diseases. (4) Mental diseases: hyperventilation, anxiety, depression, etc. (5) Others: hyperthyroidism, hypertension, severe anemia, hypoxemia, etc. 2. Cardiac diseases other than coronary heart disease: those that can induce chest pain include pericarditis, severe uncontrolled hypertension, aortic stenosis, hypertrophic cardiomyopathy, dilated cardiomyopathy, arrhythmia, aortic dissection, etc.

(IV) Key points of treatment: Comprehensive prevention and treatment, with prevention of myocardial infarction being the most important. There are two main purposes of treatment: first, to prevent myocardial infarction and sudden death, and second, to reduce and relieve symptoms. The former is the most important. 1. Prevention of myocardial infarction and sudden death, and improvement of prognosis. (1) Antiplatelet drugs: Aspirin 75-150mg/day. It should be used by all patients without contraindications. Patients who cannot tolerate aspirin can use clopidogrel as an alternative treatment. (2) Lipid-lowering drugs: All patients with coronary heart disease should use them (regardless of blood lipid level). In addition to lowering lipids, statin therapy also has beneficial effects such as delaying and reversing the progression of atherosclerotic plaques, stabilizing plaques, and anti-inflammation. The target value of LDL-C for patients with coronary heart disease should be <2.60 mmol/L (100mg/dl). For patients with very high risk, the treatment target is LDL-C <2.07 mmol/L (80mg/dl). (3) ACEI and ARB drugs: ACEI should be used in patients with stable angina, especially those with diabetes, chronic kidney damage, heart failure or left ventricular systolic dysfunction.