Tension angina: diagnosis

The diagnosis of angina is suggested by the occurrence of typical chest discomfort that increases with physical exertion and decreases at rest. Patients with chest discomfort lasting more than 20 minutes or occurring at rest, or who have experienced syncope or cardiac arrest, are classified as having acute coronary syndrome. Chest discomfort may also be caused by gastrointestinal disorders (eg, gastroesophageal reflux, esophageal spasm, dyspepsia), costal cartilaginitis, anxiety, panic attack, hyperventilation, and various cardiac diseases (eg, pericarditis, mitral valve prolapse, supraventricular tachycardia, atrial fibrillation), even in cases where coronary blood flow is not altered.

Examination. If characteristic symptoms are present, an ECG is prescribed. Since angina symptoms quickly disappear at rest, it is very rarely possible to perform an ECG during an attack, with the exception of a stress test. If an ECG is performed during an attack, it is possible to see changes characteristic of transient ischemia: segment depression (a typical change), segment elevation above the isoline, a decrease in the height of the I wave, impaired intraventricular conduction or conduction along the His bundle branch, and the development of arrhythmia (usually ventricular extrasystole). Between attacks, ECG data (and usually LV function) at rest are within normal limits in approximately 30% of patients with a typical history of angina, even in cases of three-vessel disease. In the remaining 70% of cases, the ECG reflects a history of myocardial infarction, the presence of hypertrophy, or nonspecific changes in the segment, T wave (ST-T). Changes in resting ECG data (without additional examination) do not confirm or refute the diagnosis.

More accurate tests include stress testing with ECG or myocardial imaging (eg, echocardiography, radionuclide imaging) and coronary angiography. These tests are needed to confirm the diagnosis, assess the severity of the disease, determine the appropriate level of physical activity for the patient, and assess the prognosis.

First, noninvasive tests are prescribed. The most reliable tests for diagnosing coronary heart disease are stress echocardiography and myocardial perfusion photon emission computed tomography or PET. However, these tests are more expensive than a simple stress ECG.

If the patient has a normal resting ECG and can tolerate exercise, a stress test with ECG is used. In men with angina-like chest discomfort, a stress test with ECG has a specificity of 70% and a sensitivity of 90%. Sensitivity in women is similar, but specificity is lower, especially in women younger than 55 years (< 70%). However, women are more likely than men to have resting ECG abnormalities in the absence of coronary artery disease (32% vs. 23%). Although sensitivity is high, a stress test with ECG may miss serious coronary artery disease (even in left main or three-vessel disease). In patients with atypical symptoms, a negative stress test with ECG usually rules out angina and coronary artery disease; a positive result may indicate the presence or absence of myocardial ischemia and requires further testing.

When resting ECG data changes, false-positive segment changes are often encountered during stress ECG, in which case myocardial visualization is necessary against the background of a stress test. Stress tests with physical or pharmacological (with dobutamine or dipyridamole) load can be used. The choice of visualization option depends on the technical capabilities and experience of the expert. Visualization methods help to evaluate LV function and response to stress, identify areas of ischemia, infarction and viable tissue, determine the area and volume of myocardium at risk. Stress echocardiography also allows to determine mitral regurgitation caused by ischemia.

Coronary angiography is the standard diagnostic tool for ischemic heart disease, but it is not always necessary to confirm the diagnosis. This test is primarily used to assess the severity of coronary artery disease and the location of lesions when revascularization is possible [percutaneous angioplasty (PCA) or coronary artery bypass grafting (CABG)]. Angiography may also be used when knowledge of coronary anatomy is necessary to determine work capacity and lifestyle changes (e.g., stopping work or playing sports). Obstruction to blood flow is considered physiologically significant when the lumen diameter is reduced by more than 70%. This reduction directly correlates with the presence of angina pectoris when arterial spasm or thrombosis is not associated.

Intravascular ultrasound provides visualization of the coronary artery structure. An ultrasound probe placed on the tip of a catheter is inserted into the coronary artery during angiography. This test provides more information about the anatomy of the coronary arteries than other methods. Intravascular ultrasound is used when the nature of the arterial injury is unclear or when the apparent severity of the disease does not correspond to the symptoms. When used during angioplasty, it ensures optimal stent placement.

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