As the incidence of coronary heart disease is increasing and the survival rate of myocardial infarction is improving, proper diagnosis of coronary heart disease and reasonable secondary prevention have become the basic requirements for cardiovascular physicians. Although invasive coronary angiography is the “gold standard” for the diagnosis of coronary heart disease, it is not a means to “screen” for coronary heart disease, and the positivity rate of coronary angiography in some medical units is less than 50%, resulting in a great waste of medical resources. Various non-invasive imaging examinations have flourished in recent years and have been widely used, including echocardiography, cardiac nuclear imaging (including myocardial perfusion, myocardial metabolic imaging and cardiac blood pool imaging), multilayer spiral CT, cardiac magnetic resonance imaging, etc. The application status of cardiac nuclear imaging has been greatly improved in the past 30 years. The three elements of coronary artery disease diagnosis: vascular, myocardial, and hemodynamic A complete diagnosis of coronary artery disease should include information on 3 aspects: vascular, myocardial, and hemodynamic. Coronary angiography provides diagnostic information on the anatomy and morphology of the coronary arteries and determines the site and extent of stenosis. Myocardial perfusion imaging (MPI), on the other hand, reflects myocardial perfusion and reveals the relationship between stenotic vessels and ischemic myocardium. MPI includes both resting and loading types, and resting MPI already shows significant myocardial perfusion deficit, which cannot exclude myocardial infarction, while patients with suspicious medical history and/or ECG showing cool myocardial infarction pattern can help to diagnose myocardial infarction. The diagnosis of myocardial ischemia in coronary artery disease and the assessment of efficacy after coronary revascularization need to be performed in a loading test state. This is because in patients with coronary artery disease without myocardial infarction, MPI can be normal at rest, even if the degree of coronary stenosis is 90% to 95%. However, during exercise or drug loading, the hemodynamics of the stenotic coronary arteries can change significantly and the MPI can become significantly abnormal. Both exercise and drug loading tests are currently the most commonly used loading methods. MPI can not only qualitatively determine the presence or absence of myocardial ischemia, but also detect the location of myocardial ischemia, quantify the extent and degree of myocardial ischemia, and capture information on left ventricular function and myocardial motion, greatly enhancing the clinical value of MPI in diagnosing coronary artery disease, performing risk stratification and prognostic assessment. Adenosine loading nuclide MPI: coronary heart disease diagnosis, risk stratification and prognosis assessment The 2003 American College of Cardiology/American Heart Association/American Society of Nuclear Cardiology (ACC/AHA/ASNC) Guidelines for the Clinical Application and Practice of Nuclide MPI pointed out three important clinical applications of adenosine loading nuclide MPI, namely coronary heart disease diagnosis, risk stratification and prognosis assessment. 1.Diagnosis of coronary heart disease The diagnostic value of adenosine loading test for coronary heart disease is similar to that of exercise loading test. However, adenosine can produce the greatest vasodilatory effect in most subjects, with a sensitivity of 87%-92% and specificity of 81%-100%. The guidelines state that adenosine loading nucleotide MPI is suitable for the following groups: (1) Those with suspected coronary artery disease, especially those with atypical symptoms, to avoid unnecessary invasive testing. (2) Patients who cannot tolerate exercise or have low accuracy of exercise test, mainly including: (1) those who cannot tolerate exercise test for various reasons; (2) those who cannot easily achieve the target heart rate after taking β-blockers; (3) women with decreased diagnostic accuracy and high false positive rate of exercise ECG; (4) diabetic patients with coronary artery and microcirculation lesions and atypical symptoms; (5) patients with bundle branch block or left ventricular hypertrophy on ECG (5) Patients with bundle-branch conduction block or left ventricular hypertrophy on the electrocardiogram. The diagnostic sensitivity, specificity and accuracy of adenosine-loaded MPI are significantly increased, which facilitates early diagnosis. (3) Screening physical examination for people without conscious symptoms who are engaged in high-risk occupations. (4) Patients who do not want to do or cannot afford coronary angiography financially. 2.Localization of coronary lesions The site, extent and degree of myocardial ischemia can be determined by nuclear MPI, and the offender vessel can be inferred. 2002 AHA published the standardized method of myocardial segmentation, 17 myocardial segments are supplied with blood by different coronary arteries, and the lesion vessel can be inferred from the blood perfusion of myocardial segments (Figure 1). At present, single photon emission computed tomography (SPECT) can be combined with 16-row spiral CT on the same machine and adenosine loaded nuclide MPI, which is more conducive to the simultaneous determination of myocardial ischemia and criminal vessels, as well as the diagnosis of coronary artery lesions and their extent from the vascular level and myocardial level. 3. Risk stratification judgment High-risk patients have the following MPI characteristics: ① multiple defects or larger irreversible perfusion defects in the supply area of more than two coronary arteries; ② larger reversible defects in quantitative or semi-quantitative analysis; ③ increased uptake of myocardial imaging agent in the lung after loading; ④ transient enlargement of the left ventricular volume after loading; ⑤ reversible perfusion defects in the distribution area of the left main coronary artery. Adenosine loading nuclide MPI can effectively monitor the changes of the disease. The New Standards for the Prevention of Acute Exacerbation Reduction Study (INSPIRE) showed that adenosine loading 99mTc (Tc)-SPECT can provide accurate risk stratification very early after acute infarction (AMI) and effectively monitor changes in myocardial ischemia before and after anti-myocardial ischemic drugs or coronary revascularization therapy (Figure 2), and its results are also independent predictors of recurrent cardiac events. The results are also independent predictors of recurrent cardiac events. It is often necessary to know the patency rate and the occurrence of new lesions after coronary revascularization, and patients are often seen for various types of discomfort after the procedure. If every visit is followed by a review with imaging, not only does it increase medical costs, but it can also confuse patients with mild to moderate stenosis lesions, and even place stents that do not need to be placed. The non-invasive MPI examination can determine whether the patient has obvious myocardial ischemia relatively easily, which greatly reduces the economic and ideological burden of the patient. 5, adverse reactions The safety factor of adenosine loaded nucleotide MPI is very high, and adenosine has been marketed for more than 10 years with “zero” clinical deaths. Adverse reactions are common, but mostly mild, such as facial flushing, dyspnea, chest pain, etc. Because of the very short half-life of adenosine (<10 seconds), adverse reactions can disappear within a few minutes after stopping the injection. Previously used Pansentine has more adverse reactions and longer duration, which are basically eliminated in large hospitals. Contraindications to adenosine include: second or third degree atrioventricular block; sinus node disease (with the exception of patients with artificial pacemakers); and patients with known or estimated bronchial stenosis or bronchospasm with pulmonary disease. Because adenosine is endogenous, clinical hypersensitivity, hemolysis, and vascular toxicity do not occur. ACC/AHA/ASNC guidelines have repeatedly emphasized the use of MPI as a "gatekeeper" for coronary angiography in order to reduce unnecessary angiography, improve the clinical diagnosis of coronary artery disease, and reduce medical costs. To reduce unnecessary angiography, improve clinical diagnosis of coronary artery disease, and reduce medical costs. In addition, it is important to emphasize that the accuracy of diagnostic imaging is empirically dependent and varies widely among hospitals and physicians. All imaging physicians must compare the results with invasive coronary angiography in order to continuously improve the accuracy of diagnosis. Many large hospitals have increasingly sophisticated MPI examinations with high accuracy and widespread use. Clinicians should use these examinations correctly for different purposes and conditions to make the diagnosis and treatment of coronary artery disease more accurate and to benefit more patients. Top Middle of short axis Bottom Middle of long vertical axis The 17 myocardial segments are supplied by different coronary arteries: 1, 2, 7, 8, 13, 14, 17 are supplied by the left anterior descending branch (LAD); 3, 4, 9, 10, 15 are supplied by the right coronary artery (RCA); 5, 6, 11, 12, 16 are supplied by the left circumflex branch (LCX).