What phase of ACS is characterized by myocardial ischemia?

The first phase of Acute Coronary Syndrome (ACS) is characterized by myocardial ischemia, which occurs when there is a reduction in blood flow to the heart muscle, typically due to a blockage in the coronary arteries. This phase encompasses various clinical presentations, including unstable angina and non-ST elevation myocardial infarction (NSTEMI).

During this initial phase, the heart experiences a significant oxygen supply-demand mismatch, leading to ischemic pain, often referred to as angina. If the ischemia is severe or prolonged, it can result in myocardial injury or infarction. Understanding this phase is crucial for timely diagnosis and intervention to restore blood flow and minimize damage to the heart muscle.