Diagnosis
In the case of stable angina, the mainstay of diagnosis is stress ECG. However, such a test is contraindicated in unstable angina as it can lead to a fatal outcome -owing to the fact that in unstable angina, the demand of the heart is greatly exceeding the supply at rest-. In most cases, the mainline of diagnosis is coronary angiography, where imaging of the coronaries either by MRI or echocardiography can provide enough information regarding the condition of the arteries and the presence of a thrombus or an infarction.
Regarding ECG, the main difference between stable and unstable angina is that while the stable type shows a characteristic ST-segment depression on stress ECG or rest ECG during the attack, unstable angina shows multiple changes, which include ST-segment depression, elevation, or T-wave changes. It is crucial to differentiate between the ST elevation of unstable angina and that of myocardial infarction (heart attack). The main difference is the duration, where the elevation is transient in unstable angina and fixed in myocardial infarction.
