Initial CT Perfusion-Guided Strategy for Suspected NSTEMI

Acute myocardial infarction (AMI) is caused by acute and persistent ischemia and hypoxia of the coronary arteries, leading to myocardial necrosis. Clinically, it often presents as severe and prolonged retrosternal pain, accompanied by elevated serum myocardial enzyme levels and progressive changes in the electrocardiogram (ECG). Complications may include arrhythmias, shock, or heart failure, which can be life-threatening.

Non-ST elevation myocardial infarction (NSTEMI) is a more complex type of AMI. It presents with chest pain and elevated troponin levels, but without clear ischemic changes on the ECG, making clinical diagnosis challenging. Additionally, NSTEMI patients are highly heterogeneous, influenced by factors like lifestyle and inflammation. Current clinical guidelines recommend coronary angiography for these patients. However, previous studies have shown that approximately one-third of suspected NSTEMI patients do not exhibit significant coronary stenosis on angiography. Minimizing unnecessary invasive coronary angiography for such patients has become a pressing issue.

Recent clinical studies have explored the value of initial imaging tests in guiding treatment strategies for NSTEMI patients. The CARMENTA study found that performing CTA or MRI as the first-line test in suspected NSTEMI patients could reduce the need for subsequent invasive coronary angiography by 13% and 34%, respectively, and improve the positive detection rate on later angiography. The OxAMI study also showed that in patients with suspected NSTEMI who underwent MRI, only 67% had myocardial infarction, and even among those who subsequently underwent angiography and were found to have severe stenosis, CMR indicated infarction in only 84%. These findings suggest that while CTA can help rule out some myocardial infarction cases, its diagnostic value in suspected NSTEMI remains limited.

With advances in imaging technology, CT myocardial perfusion (CTP) has shown potential in more accurately identifying ischemic myocardium in coronary artery disease patients, thereby enhancing the diagnostic power of CTA. However, the diagnostic value of CTP for suspected NSTEMI patients remains unclear. Furthermore, technology now allows for simultaneous CTA and CTP testing without significantly increasing radiation exposure. This combined approach offers promise for more accurate diagnosis in suspected NSTEMI patients without a marked increase in radiation dose.

Therefore, this study aims to investigate the diagnostic and therapeutic value of an initial CTP strategy in suspected NSTEMI patients. Additionally, we will conduct a cardiovascular health questionnaire survey to explore the impact and prognostic value of adverse lifestyle factors and inflammation levels in these patients.

Inclusion criteria

• Patients with stable chest tightness or chest pain, aged ≥18 years
• No ST elevation or dynamic ST-T changes on the ECG
• Elevated TNT (greater than 14 ng/L three hours after symptom onset)

Exclusion criteria

• Persistent chest pain or ECG indicating dynamic ST-T changes,
• Hemodynamic instability
• Known history of coronary artery disease
• Contraindications for CT perfusion or coronary angiography
• Coexisting conditions such as pregnancy, cancer, severe valvular heart disease, or liver/kidney dysfunction
• Other diseases with a life expectancy of less than one year
• Inability to sign informed consent or, in the researcher's judgment, poor compliance, making it unlikely the patient can complete the study as required.