What Are the Diagnostic Criteria for Coronary Heart Disease
Coronary angiography remains the most reliable method for diagnosing coronary heart disease (CHD). This imaging technique allows physicians to directly visualize the location and severity of vascular lesions. Coronary artery stenosis is typically categorized into four grades, with a stenosis exceeding 50% considered clinically significant for CHD diagnosis. When the narrowing surpasses 75%, patients often experience noticeable ischemic symptoms. However, due to its invasive nature, coronary angiography is not ideal for large-scale clinical screening.As a less invasive alternative, clinicians frequently rely on a combination of diagnostic tools to evaluate CHD. These include blood tests for cardiac enzymes, electrocardiograms (ECGs), nuclear myocardial scans, coronary CT angiography, and stress tests. For instance, in patients experiencing myocardial infarction, ECGs may show ST-segment elevation or depression, accompanied by elevated cardiac enzyme levels—particularly troponin, which is highly indicative of acute myocardial infarction.
Non-Invasive Diagnostic Approaches
Imaging techniques such as echocardiography can reveal segmental wall motion abnormalities in ischemic regions of the heart. Nuclear myocardial perfusion imaging is also valuable in identifying areas of reduced blood flow. During episodes of angina, ECGs commonly show ST-segment depression, which typically normalizes once the angina subsides.
Role of Stress Testing in Diagnosis
In cases where resting ECGs appear normal, a stress test can be particularly useful. This test involves monitoring ECG changes during physical exertion. As the intensity of exercise increases, patients may develop typical angina symptoms along with ST-segment depression, indicating a positive stress test result. These findings serve as important indicators for possible coronary artery disease and can support further diagnostic evaluation.