Final answer:
A significant rise in cardiac troponin, typically more than 20%, with at least one value above the 99th percentile, helps diagnose cardiac ischemia. Other tests, such as an ECG, are used in conjunction with troponin levels to confirm an MI.
Step-by-step explanation:
To diagnose cardiac ischemia, a significant rise in cardiac troponin levels is essential. Cardiac troponin is a regulatory protein for muscle contraction, and its levels rise when cardiac muscle cells are damaged, as might occur during myocardial infarction (MI).
Various guidelines suggest different criteria for what constitutes a significant rise, but a common standard is a troponin increase of more than 20% with at least one value above the 99th percentile upper reference limit.
It's important to interpret troponin levels in conjunction with clinical findings and other diagnostic tests, like an electrocardiogram (ECG), to confirm myocardial infarction (MI). An MI can often cause ECG changes, such as ST segment elevation or depression, and Q wave alterations. Furthermore, Myocardial infarctions are classified as either ST-elevated MI (STEMI) or non-ST-elevated MI (non-STEMI).