Whatever the mechanism generating the phenomenon, ST-segment elevation on an ECG is the hallmark of evolving myocardial infarction secondary to complete occlusion of a coronary artery of vessel.
Depending on the location and the extent of obstruction, one of the following conditions may result: - Unstable angina, - Non-ST-segment elevation myocardial infarction, NSTEMI, - Or ST-segment elevation myocardial infarction, STEMI.
First, it's super important to remember that in each case, the injury to cardiomyocytes isn't permanent, meaning it's reversible and the cardiomyocytes don't die (which is how this differs from myocardial infarction).
Just like a garden hose that's always under high pressure, in the long term, blood vessels can develop tiny cracks and tears that can lead to serious problems, like myocardial infarctions, aneurysms, and strokes.
Unstable angina, for the same reason as stable angina, involves subendocardial ischemia and it should be treated as an emergency, because patients are at a high risk of progressing to myocardial infarction, or heart attack.
Peaked T-waves, ST segment elevation, and alterations to the terminal portion of the QRS complex are the early changes of acute myocardial infarction secondary to complete occlusion of a coronary arterial vessel.
The key distinction is that unstable angina means that the heart tissue is alive but ischemic or starving for oxygen, whereas myocardial infarction means that the areas of heart tissue have already begun to necrose or die.
Symptoms of coronary steal syndrome mimic that of a myocardial infarction, and include a typical type chest pain, which is described as a squeezing pain or pressure that might radiate up to the left arm, jaw, shoulders, or back.