Non-ST-segment elevation myocardial infarction (NSTEMI) and unstable angina (UA) belong to the same category of non-ST-segment elevation acute coronary syndrome (NSTE-ACS), while non-ST-segment elevation myocardial infarction (NSTEMI) is a special type of NSTE-ACS, which is conceptually distinguished from ST-segment elevation mainly on the basis of whether the ST-segment of the relevant leads of the ECG is elevated or not myocardial infarction (STEMI). Whether NSTEMI, STEMI or UA are important types of acute coronary syndrome, only the severity of the lesion is different, modern research has shown that the pathological basis of acute coronary syndrome is the rupture of unstable plaque in the coronary arteries, intracoronary thrombosis and lead to varying degrees of vascular obstruction, NSTE-ACS is often due to coronary thrombosis caused by incomplete obstruction of the coronary lumen NSTE-ACS is often caused by incomplete coronary lumen obstruction due to intracoronary thrombosis. Unlike STEMI, NSTEMI, in addition to reflecting the non-complete occlusion of the coronary arteries, there are differences in the composition of the thrombus, which is dominated by platelets, that is, white thrombus, the general fibrinolytic drugs on the “white thrombus” is ineffective, so thrombolytic therapy is prohibited for such patients.
Acute coronary syndromes are seen in people of all ages, races and socioeconomic backgrounds. NSTEMI patients are easily missed in primary care because of the absence of ST-segment elevation on the electrocardiogram, and the clinical manifestations of these patients vary in severity and can be The prognosis of NSTEMI patients is very good.
The prognosis of NSTEMI patients also varies greatly, so NSTEMI has been one of the focal points of medical research. For a long time, there has been more disagreement about the treatment of NSTEMI because of the specificity of its pathogenesis. Recent research advances are mainly focused on conservative treatment and interventional treatment, today NSTEMI interventional management strategy to explain.
First, the first assessment, clear diagnosis?
For patients with chest pain or chest discomfort, patients must be assessed immediately based on their complaints, limited data, physical examination and simple targeted tests, the assessment includes: 1, the nature of chest pain, duration and the signs manifested by the various complications caused by chest pain, and then on this basis basically exclude other diseases causing chest pain, so as to make a preliminary diagnosis of coronary heart disease; 2. Risk factors for coronary artery disease: such as age, risk factors, previous myocardial infarction, whether or not the patient has received coronary artery bypass grafting and percutaneous coronary intervention, etc.; 3. ECG: observe whether there are ST segment changes; 4. Blood specimens: at least troponin T or I,CK-MB, creatinine, myoglobin and white blood cell count should be measured. On the basis of the above differentiate the diagnosis: ACS and non-ACS, ACS then distinguish NSTE-ACS and STEMI, if the proposed diagnosis of NSTEMI need to be the next step in the definitive diagnosis. Oral and intravenous medications are needed before definitive diagnosis, and then more information is collected to clarify the diagnosis: 1, detailed history, which is the most important diagnostic basis; 2, echocardiography, multi-row spiral CT, magnetic resonance imaging and nuclear imaging to exclude aortic coarctation, pulmonary embolism, etc.; 3, most patients with ACS do not have abnormal signs; 4, repeat ECG ST-segment testing; 5, normal ECG (especially after remission of symptoms) and normal serum myocardial marker results (especially early onset) do not exclude NSTEMI and should be reviewed dynamically.
Second, risk assessment, guiding strategy?
Current ACC/AHA guidelines recommend invasive therapy for patients with recent-onset intractable angina or hemodynamically unstable NSTE-ACS, and clinical stratification for the above stable patients using scoring tools, which currently include TIMI, PURSUIT, and GRACE. The three scoring methods, Thrombolysis in Myocardial Infarction (TIMI) score, Platelet Glycoprotein IIb/IIIa Receptor Antagonist Etibatide for Acute Coronary Syndrome (PURSUIT) score, and Global Registry of Acute Coronary Events (GRACE) score, are all from large clinical trials of NSTE-ACS.
1, Risk factors for TIMI score to predict endpoint events include.
(1) Age ≥65 years.
(2) At least three risk factors for coronary artery disease (diabetes, hypertension, family history, lipid abnormalities, smoking).
(3) Coronary angiographic stenosis >50%; previous history of PCI or CABG.
(4) ST segment changes (deviation ≥0.5 mm).
(5) Severe anginal symptoms (angina ≥2 times in 24 hours).
(6) Application of aspirin within 7 days.
(7) Elevated cardiac enzymes (CK-MB and or cTn). TIMI scoring system total score 0-7, low risk: 0-2; medium risk: 3-4; high risk: 5-7.
Risk factors for endpoint events predicted by the PURSUIT score include (1) age, (2) sex, (3) symptoms of angina, (4) ST-segment depression, and (5) signs of heart failure.
The GRACE score predicts risk factors for endpoint events: (1) age; (2) Killip classification; (3) arterial blood pressure; (4) heart rate; (5) ST-segment depression; (6) cardiac arrest; (7) blood creatinine level; and (8) myocardial-specific troponin. the total GRACE score is 0-258, and a GRACE score >140 is high risk.
The currently applied criteria for early risk assessment stratification are mainly derived from large-scale clinical trials and guidelines or expert consensus introduced by professional associations in cardiovascular medicine.
2. High-risk indicators include.
(1) significantly longer duration of angina attack at rest (more than 20 min) than before.
(2) Angina attack with persistent ST-segment depression of more than 0.1mV or transient ST-segment elevation.
(3) Angina attack with heart failure or reduced blood pressure.
(4) Angina attack even after 48h of standard drug treatment.
(5) Elevated markers of myocardial necrosis (creatine kinase, creatine kinase isoenzyme, troponin T or I).
(6) Interventional treatment or history of coronary artery bypass grafting (CABG) within 6 months.
Intermediate risk indicators include.
(1) Age over 65 years.
(2) History of old myocardial infarction.
(3) History of diabetes mellitus.
(4) persistent sT-T ischemic changes or symmetrical T-wave inversions of 0.2 mV or greater on the ECG after angina resolution.
(5) Frequent angina attacks within 2 weeks.
Patients with high-risk or multiple intermediate-risk indicators should be treated with early revascularization and have 30-d and 1-year mortality risk prediction using the TIMI risk score. Recent studies have shown that growth differentiation factor-15 and serum markers of congestive heart failure (especially B-type natriuretic peptide) are independent risk factors for death in patients with NSTEMI.
III. Interventional modalities, with imaging as the first
The extent and characteristics of the lesion shown on imaging will determine the indication for revascularization and the choice of revascularization. The ability to perform PCI is also predicated on coronary angiography. The purpose of early coronary angiography is to define the extent of the lesion, its distribution, the degree of stenosis, and the type of revascularization that is appropriate. Coronary angiography can significantly improve the reliability of prognostic stratification, provide reference for patient treatment and prognosis, and provide effective help for the selection of treatment plan. Can elective CABG surgery.
Usually NSTEMI patients should undergo coronary angiography as soon as possible when.
(1) Patients with NSTEMI with significant hemodynamic instability.
(2) Recurrent symptoms of myocardial ischemia despite adequate pharmacological therapy.
(3) High risk of clinical presentation, e.g., ischemia-related congestive heart failure or malignant ventricular arrhythmias.
(4) Myocardial infarction or large area of myocardial ischemia with noninvasive tests showing left heart dysfunction and left ventricular ejection fraction (LVEF) <35%.
(5) Those who have undergone PCI or CABG and have recurrent myocardial ischemia. The next interventional strategy will be decided by the imaging results.
IV. Intervention-based, preferable strategy
Whether to routinely perform early PCI in NSTEMl patients has been the focus of debate in the medical community and has been inconclusive. From the relevant studies in recent years including the FRISCll, TACTICS and ISAR-C00L trials, it can be seen that for non-ST-segment elevation ACS, especially high-risk ACS patients, early PCI supplemented with adequate anti-ischemic and anti-platelet drugs and Intensive lipid-lowering therapy to observe near- and long-term focal events (death, reinfarction, and rehospitalization for ACS) has a better clinical outcome than choosing conservative treatment. Based on this, the 2011 AHA/ACCF recommended early intervention as Class I for NSTE-ACS when the following conditions are present.
(1) Patients with UA/NSTEMI with intractable angina or hemodynamic/electrical instability (without severe coexisting disease or contraindications to surgery).
(2) Patients with UA/NSTEMI with a high risk of clinical events.
(3) Patients with UA/NSTEMI with 1 or 2 branch lesions, with or without anterior descending branch lesions, with a high risk and a large amount of surviving myocardium.
(4) Patients with UA/NSTEMI with normal coronary anatomy, normal left ventricular function, and multiple coronary lesions without diabetes mellitus.
For early invasive treatment of patients with NSTEMI, the AHA/ACCF recommends that invasive treatment be preferred if the patient has one of the following characteristics.
(1) resting or recurrent angina attacks with low activity tolerance after intensive therapy.
(2) Elevated myocardial markers.
(3) New or suspected new-onset ST-segment depression.
(4) Heart failure with mitral regurgitation.
(5) Non-invasive tests revealing high-risk manifestations.
(6) Hemodynamic instability.
(7) Persistent ventricular tachycardia.
(8) PCI performed 6 months ago.
(9) Previous CABG.
(10) High risk score (TIMI, GRACE).
(11) Reduced left ventricular function (EF less than 40%).
Among these, cardiac bypass grafting (CABG) should be performed in patients who are eligible for coronary triple vessel disease with a left ventricular ejection fraction (LVEF) <0.4 or left main stem disease.
In some low-risk patients who start with a conservative treatment strategy, the patient should be closely monitored for recurrence of chest pain, signs of ischemia, repeated ECG, monitoring of ST-segment changes, and serial myocardial markers (CK-MB, troponin). Even in the absence of these manifestations, the patient may still be a patient with severe coronary artery disease, so a stress test must be done before discharge to clarify whether the patient is in a stable state and whether there is significant coronary artery obstruction. It should be emphasized. Although the recent prognosis of NSTEMI is good, some studies have shown that its long-term prognosis is worse. The recurrence rate of angina in the conservative treatment group is high, and 64.0% of these patients eventually require intervention, therefore, for this group of patients also need to focus on strengthening the secondary prevention treatment of coronary heart disease, such as recurrent angina, then should go to hospitals with interventional conditions for interventional PCI treatment.
In summary, according to the urgency of the risk of cardiovascular events and the severity of related complications, NSTE-ACS treatment strategies can be divided into three categories: conservative treatment strategies, emergency invasive strategies and early invasive strategies.
1. Conservative treatment strategy: Patients who meet the following criteria can be considered as low-risk patients and should not be evaluated for early invasive disease unless new clinical conditions arise: 1. no recurrent chest pain; 2. no signs of heart failure; 3. normal initial electrocardiogram and its subsequent 6-12 h electrocardiogram; 4. normal troponin levels at presentation and its subsequent 6-12 h. Patients judged as low risk by risk score also support conservative treatment strategy.
2. Urgent invasive strategy: Urgent invasive strategy should be adopted (as soon as possible) for those who meet the following characteristics.
(1) Refractory angina (e.g., progressive myocardial infarction without ST-segment abnormalities).
(2) Recurrence of chest pain with ST-segment downshift >2 mm or deep T-wave inversion despite intensive anti-anginal therapy.
(3) The presence of clinical signs of heart failure or hemodynamic instability (shock).
(4) The presence of life-threatening arrhythmias (ventricular fibrillation or ventricular tachycardia). For such patients, a glycoprotein IIb/IIIa receptor inhibitor (e.g., tirofiban) should also be administered prior to undergoing catheterization.
3. Early invasive strategy: Patients with the following characteristics should be treated with an early invasive strategy.
(1) Elevated troponin levels.
(2) Presence of dynamic ST-segment changes (>0.5 mm) or T-wave changes (symptomatic or asymptomatic).
(3) Diabetes mellitus.
(4) Decreased renal function (GFR <60 ml/min-1.73 m2).
(5) Reduced left ventricular ejection fraction (<40%).
(6) Early post-infarction angina.
(7) Within 6 months after percutaneous coronary interposition therapy.
(8) Previous coronary artery bypass grafting.
(9) Patients assessed as moderate to high risk according to the risk score. The exact timing of cardiac catheterization may depend on local hospital conditions, but should be completed within 72 h. If there is no significant risk of bleeding, glycoprotein IIb/IIIa receptor inhibitors should also be given to patients with elevated troponin, dynamic ST/T changes, or diabetes mellitus before undergoing catheterization.
V. Secondary prevention, drug foundation?
Comparing the prognosis of patients with NSTEMI and STEMI, the former has a better prognosis than the latter in the near term and a poorer prognosis in the long term, while the latter has a poorer prognosis than the former in the near term and a slightly better prognosis in the long term, which therefore requires that patients with NSTEMI be discharged from the hospital with attention to preventing myocardial reischemia and necrosis while correcting all risk factors that promote atherosclerosis. Continuation of aspirin, clopidogrel, and B-blockers is required. Routinely use statins to intensify lipid lowering, use angiotensin-converting enzyme inhibitors to inhibit myocardial remodeling, actively control hypertension and hyperglycemia, quit smoking, eat a reasonable diet to maintain ideal body weight, adhere to moderate exercise, flu vaccination, etc., and maintain a good psychological status and optimism.