What are the implications of transient ST changes on the ECG with regards to the diagnosis of Acute Coronary Syndrome (ACS)?
Transient ST changes (0.5 mm [0.05 mV]) during symptoms at rest strongly suggest ischemia and underlying severe Coronary Artery Disease (CAD). Patients without acute ischemic changes on ECG have a reduced risk of Myocardial Infarction (MI) and a very low risk of in-hospital life-threatening complications, even in the presence of confounding electrocardiographic patterns such as Left Ventricular (LV) hypertrophy. ST depression (especially horizontal or downsloping) is highly suggestive of Non-ST-Elevation Acute Coronary Syndrome (NSTE-ACS). Marked symmetrical precordial T-wave inversion (2 mm [0.2 mV]) suggests acute ischemia, particularly due to a critical stenosis of the left anterior descending coronary artery; it may also be seen with acute pulmonary embolism and right-sided ST-T changes.